U.S. patent application number 15/141902 was filed with the patent office on 2017-01-05 for multiple non-conductive polymer substrates and conductive coatings and methods for detecting voc.
The applicant listed for this patent is GM Global Technology Operations LLC. Invention is credited to DEBEJYO CHAKRABORTY, NILESH D. MANKAME, KEVIN H. PETERSON, JAMES R. SALVADOR.
Application Number | 20170003238 15/141902 |
Document ID | / |
Family ID | 57609407 |
Filed Date | 2017-01-05 |
United States Patent
Application |
20170003238 |
Kind Code |
A1 |
SALVADOR; JAMES R. ; et
al. |
January 5, 2017 |
MULTIPLE NON-CONDUCTIVE POLYMER SUBSTRATES AND CONDUCTIVE COATINGS
AND METHODS FOR DETECTING VOC
Abstract
A product for sensing may include a non-conductive layer of a
polymer that may be selected for its responsiveness to a stimulus
from one of a selected analyte, or a selected group of analytes.
The non-conductive layer may be non-conductive of an electrical
current. A conductive layer may be in contact with the
non-conductive layer and may be conductive of the electrical
current. A lead for may provide an electric current to the
conductive layer. A device may be provided to detect at least one
property of the conductive layer in response to the stimulus.
Inventors: |
SALVADOR; JAMES R.; (ROYAL
OAK, MI) ; CHAKRABORTY; DEBEJYO; (NOVI, MI) ;
PETERSON; KEVIN H.; (DETROIT, MI) ; MANKAME; NILESH
D.; (ANN ARBOR, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GM Global Technology Operations LLC |
Detroit |
MI |
US |
|
|
Family ID: |
57609407 |
Appl. No.: |
15/141902 |
Filed: |
April 29, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62186568 |
Jun 30, 2015 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08L 33/12 20130101;
G01D 21/00 20130101; G01N 27/26 20130101; G01N 27/125 20130101;
G01N 27/04 20130101; G01N 27/041 20130101; C08L 23/06 20130101;
G01R 27/14 20130101; C08L 23/12 20130101 |
International
Class: |
G01N 27/04 20060101
G01N027/04 |
Claims
1. A product for sensing comprising a non-conductive layer
comprising a polymer selected for its responsiveness to a stimulus
from one of a selected analyte or a selected group of analytes, the
non-conductive layer being non-conductive of an electrical current,
a conductive layer in contact with the non-conductive layer and
being conductive of the electrical current, a lead for providing an
electric current to the conductive layer, and a device detecting at
least one property of the conductive layer in response to the
stimulus.
2. The product according to claim 1 wherein the conductive layer is
in contact with a surface of the non-conductive layer and covers
only a portion of the surface so that an area of the surface is
exposed directly to the stimulus.
3. The product according to claim 1 wherein the non-conductive
layer is comprised of areas of different polymers having different
responses to the stimulus.
4. The product according to claim 3 wherein the areas are part of
one contiguous structure.
5. The product according to claim 1 wherein the lead comprises a
first pair of leads and a second pair of leads, wherein the first
pair of leads are spaced from each other at a first distance, and
the second pair of leads are spaced from each other at a second
distance that is greater than the first so that the first and
second pairs of leads communicate a different response to the
stimulus.
6. The product according to claim 1 wherein the device comprises a
data acquisition module in communication with the lead to collect
information on responses to the stimulus.
7. The product according to claim 1 wherein the lead is applied to
the conductive layer.
8. The product according to claim 1 wherein the lead is disposed
between the conductive layer and the non-conductive layer.
9. The product according to claim 1 wherein the lead comprises a
number of spaced apart leads.
10. The product according to claim 1 comprising a semi-permeable
layer overlying one of the non-conductive layer or the conductive
layer, the semi-permeable layer having a pore size selected to pass
the selected analyte or the selected group of analytes.
11. A method of monitoring for an exposure to an analyte
comprising: providing a sensing device with a non-conductive layer;
providing a lead structure to apply a current to a zone of the
sensing device that exhibits an opposition to the current, wherein
the opposition varies in response to the exposure of the
non-conducting layer to the analyte.
12. A method according to claim 11 comprising a device to monitor
changes in the opposition, processing the changes; determining a
rate of change of the opposition, determining a magnitude of change
in the opposition, and comparing the rate of change and the
magnitude of change to classify the analyte.
13. A method according to claim 11 comprising providing the
non-conductive layer as a polymer that does not conduct the
current, applying a conductive layer to the non-conductive layer,
the conductive layer conducting the current.
14. The method according to claim 13 comprising providing the lead
structure electrically coupled with the conductive layer, providing
the zone in the conductive layer, and measuring the response of the
non-conductive layer to the exposure to the analyte by evaluating
changes in the opposition.
15. The method according to claim 14 comprising allowing the
non-conductive layer to expand in response to the exposure to the
analyte as a result of the opposition changes in the zone through
the expansion.
16. The method according to claim 11 comprising providing the
non-conductive layer as an array of different polymers selected to
have different responses to the exposure to the analyte.
17. The method according to claim 11 comprising providing a
conductive layer overlying a surface of the non-conductive layer
with areas of the surface exposed and not covered by the conductive
later to tune the sensitivity of the sensing device to the
analyte.
18. The method according to claim 11 comprising discerning between
the analyte and water vapor by providing the non-conductive layer
as a fluorinated polymer.
19. The method according to claim 11 comprising classifying the
analyte by comparing a magnitude and a rate of the opposition
change to known opposition changes for different types of
analytes.
20. The method according to claim 11 comprising quantifying a
concentration of the analyte by determining a magnitude of change
in the opposition and comparing the magnitude to known magnitudes
of change for different concentrations of the analyte.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of U.S. Provisional
Application No. 62/186,568 filed Jun. 30, 2015.
TECHNICAL FIELD
[0002] The field to which the disclosure generally relates to
includes sensor devices and methods of detecting compositions, in
particular, volatile organic compounds.
BACKGROUND
[0003] In a number of variations, sensor devices may be used to
measure environmental conditions or variables pertaining to
components.
SUMMARY OF ILLUSTRATIVE VARIATIONS
[0004] A number of illustrative variations may involve a product
for sensing that may include a non-conductive layer of a polymer
that may be selected for its responsiveness to a stimulus from one
of a selected analyte, or a selected group of analytes. The
non-conductive layer may be non-conductive of an electrical
current. A conductive layer may be in contact with the
non-conductive layer and may be conductive of the electrical
current. A lead may provide an electric current to the conductive
layer. A device may be provided to detect at least one property of
the conductive layer in response to the stimulus.
[0005] Additional illustrative variations may involve a method of
monitoring for an exposure to an analyte. A sensing device may be
provided with a non-conductive layer. A lead structure may be
provided to apply a current to a zone of the sensing device that
exhibits an opposition to the current. The opposition may vary in
response to the exposure of the non-conducting layer to the
analyte.
[0006] Other illustrative variations within the scope of the
invention will become apparent from the detailed description
provided hereinafter. It should be understood that the detailed
description and specific examples, while disclosing variations
within the scope of the invention, are intended for purposes of
illustration only and are not intended to limit the scope of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Select examples of variations within the scope of the
invention will become more fully understood from the detailed
description and the accompanying drawings, wherein:
[0008] FIG. 1 illustrates a product according to a number of
variations.
[0009] FIG. 2 illustrates examples of applications of a product
according to a number of variations.
[0010] FIG. 3 illustrates a product according to a number of
variations.
[0011] FIG. 4 illustrates a fragmentary cross section of the
product of FIG. 3 taken along the portion indicated by the line
4-4, according to a number of variations.
[0012] FIG. 5 illustrates a graph of measured resistance in
relation to concentrations of volatile organic compounds for a
product according to a number of variations.
[0013] FIG. 6 illustrates a graph of a product's response to
volatile organic compounds showing measured resistance versus time
product according to a number of variations.
[0014] FIG. 7 illustrates a product according to a number of
variations.
[0015] FIG. 8 illustrates a product according to a number of
variations.
[0016] FIG. 9 illustrates a product according to a number of
variations.
[0017] FIG. 10 illustrates a product according to a number of
variations.
[0018] FIG. 11 illustrates a product according to a number of
variations.
[0019] FIG. 12 illustrates a product according to a number of
variations.
[0020] FIG. 13 illustrates a product according to a number of
variations.
[0021] FIG. 14 illustrates an array of sensing devices according to
a number of variations.
[0022] FIG. 15 illustrates a graph of response to volatile organic
compounds in relation to measured resistance versus time of a
product according to a number of variations.
[0023] FIG. 16 illustrates a graph of response to volatile organic
compounds in relation to measured resistance versus time of a
product demonstrating a fast and reversible response according to a
number of variations.
[0024] FIG. 17 illustrates a graph of a resistance percentage
versus vapor concentration in parts per million for three analytes
as measured by a product according to a number of variations.
[0025] FIG. 18 illustrates a graph of a resistance ratio versus
time in milliseconds for four volumes of an injected analyte as
measured by a product according to a number of variations.
[0026] FIG. 19 illustrates a graph of resistance versus time in
seconds for two successive injections of an analyte as measured by
a product according to a number of variations.
[0027] FIG. 20 illustrates methods according to a number of
variations.
[0028] FIG. 21 illustrates methods according to a number of
variations.
[0029] FIG. 22 illustrates methods according to a number of
variations.
DETAILED DESCRIPTION OF ILLUSTRATIVE VARIATIONS
[0030] The following description of the variations is merely
illustrative in nature and is in no way intended to limit the scope
of the invention, its application, or uses.
[0031] FIG. 1 shows a product according to a number of variations.
In a number of variations, the product may include a sensor device
14. The sensor device 14 may include a non-conductive layer 16. The
sensor device 14 may include a conductive layer 18. The conductive
layer 18 may overlie the non-conductive layer 16, or may otherwise
be in physical contact with the non-conductive layer 16. The sensor
device 14 may be mounted in any location where sensing is desired.
In a number of variations the sensor device 14 may overlie or may
otherwise be in physical contact with a substrate 12, which in the
case of FIGS. 3 and 4 may be a battery pouch. The sensor device 14
may be constructed and arranged to measure or monitor at least one
variable. The variable may involve a physical property such as
temperature, pressure, deformation, or another property, or may
involve detection, identification, classification, tracking, or
other characteristics of a property. The variable may involve
concentration, rate, time or another characteristic of a compound,
such as volatile organic compound vapor pressure. It has been found
that a correlation exists between the time needed to reach full
saturation and the vapor pressure of the analyte. This enables a
level of discrimination between analytes. FIG. 2 depicts a graphic
representation of some applications for the sensor device 14.
[0032] The variable may involve a status of a device or environment
such as state of charge, or state of health, depletion status,
diagnosis properties, or other variables indicative of status. In a
number of variations, a plurality of sensor devices 14 may be used
to monitor the surface or space where sensing is desired, as
further described below. The sensor device 14 may include at least
one lead 22, which may be in contact with the conductive layer 18
to monitor at least one variable such as resistance or impedance.
Resistance and impedance may be generally referred to an opposition
to the passage of an applied current from a DC or AC source,
respectively, through an area of interest. In a number of
variations, the sensor device 14 may include a data acquisition
module (DAQ) 24. With additional reference to FIGS. 3 and 4, the
sensor device 14 or DAQ 24 may be electrically coupled to an
electronic control module (ECM) 25, which may be a controller for
processing information. As used herein, the term "electrically
coupled" may mean possessing the ability to transfer electrons or
electric signals between the at least two components. As used
herein, the term "electrically coupled" relationship may include a
conducting wire or may include wireless connection. In a number of
variations, at least one variable may be measured via inputs of at
least one of deformation of the non-conductive layer 16 or the
substrate 12, 15 to which it may be mounted, or change in
opposition to current of the area of interest, which may involve at
least one calculation. In monitoring changes in the opposition to
current such as between leads 22, impedance changes may be
evaluated in the aggregate or its components may be evaluated
separately. Where impedance Z=R+jX, where R is resistance, j is an
imaginary number called the j operator, and X denotes reactance. It
has been found that the imaginary component impedance may
experience greater changes than the resistance part when exposed to
certain vapors, for example, vapors of biological origin.
Accordingly, depending on the application, monitoring for, and
evaluating, changes in the imaginary component of impedance may be
useful in identifying the presence of certain vapors being
monitored.
[0033] In a number of variations, the non-conductive layer 16 may
include a polymeric material. The non-conductive layer 16 may
comprise a polymer including, but not limited to, Acrylonitrile
butadiene styrene (ABS), Polymethyl Methacrylate (PMMA), Celluloid,
Cellulose acetate, Cycloolef in Copolymer (COC), Ethylene-Vinyl
Acetate (EVA), Ethylene vinyl alcohol (EVOH), Fluoroplastics
(including PTFE, FEP, PFA, CTFE, ECTFE, ETFE)lonomers, Kydex.TM., a
trademarked acrylic/PVC alloy, Liquid Crystal Polymer (LCP),
Polyacetal (POM or Acetal), Polyacrylates (Acrylic),
Polyacrylonitrile (PAN or Acrylonitrile), Polyamide (PA or Nylon),
Polyamide-imide (PAI), Polyaryletherketone (PAEK or Ketone),
Polybutadiene (PBD), Polybutylene (PB), Polybutylene terephthalate
(PBT), Polycaprolactone (PCL), Polychlorotrifluoroethylene (PCTFE),
Polyethylene terephthalate (PET), Polycyclohexylene dimethylene
terephthalate (PCT), Polycarbonate (PC), Polyhydroxyalkanoates
(PHAs), Polyketone (PK), Polyester, Polyetheretherketone (PEEK),
Polyetherketoneketone (PEKK), Polyetherimide (PEI),
Polyethersulfone (PES), Polysulfone, Polyethylenechlorinates (PEC),
Polyimide (PI), Polylactic acid (PLA), Polymethylpentene (PMP),
Polyphenylene oxide (PPO), Polyphenylene sulfide (PPS),
Polyphthalamide (PPA), Polystyrene (PS), Polysulfone (PSU),
Polytrimethylene terephthalate (PTT), Polyurethane (PU), Polyvinyl
acetate (PVA), Polyvinyl chloride (PVC), Polyvinylidene chloride
(PVDC), Styrene-acrylonitrile (SAN), polycarbonate+acrylonitrile
butadiene styrene mix (ABS+PC), Polypropylene (PP) (including, but
not limited to, impact, random, and homo), Polyethylene (PE)
(including, but not limited to, linear low density, linear high
density), combinations or blends in any amount thereof, or may be
another type. In a number of variations, the non-conductive layer
16 may be a combination of the above polymers in any amount or
concentration. In a number of variations, the non-conductive layer
16 may include a composite layer comprising several layers of the
materials listed. In a number of variations, the non-conductive
layer 16 may be formed via a method including, but not limited to,
injection moulding, extrusion moulding, structural foam, vacuum
forming, extrusion blow moulding, a hand lay-up operation, a spray
lay-up operation, a pultrusion operation, a chopped strand mat,
vacuum bag moulding, pressure bag moulding, autoclave moulding,
resin transfer moulding, vacuum assisted resin transfer moulding,
bladder moulding, compression moulding, mandrel wrapping, wet
layup, chopper gun, filament winding, melting, staple fiber,
continuous filament, or may be formed another way.
[0034] In a number of variations, the conductive layer 18 may
include a metallic or semimetallic material. In a number of
variations, the conductive layer 18 may include a metal including,
but not limited to, plastic steel, stainless steel, copper, nickel,
tin, gold, silver, molybdenum, palladium, tungsten, graphite or
another form of carbon, zinc, iron, bronze, aluminum, titanium,
platinum, silicide, or may be another type), metallic alloys,
combinations thereof, or may be another type. In a number of
variations the conductive layer may include a non-metal material
that conducts electric current sufficiently to measure changes in
impedance or resistance. In a number of variations, the conductive
layer 18 may be a combination of the materials in any amount or
concentration. In a number of variations, the conductive layer 18
may include a composite layer comprising several layers of the
materials. In a number of variations, the conductive layer 18 may
be formed on or overlying the non-conductive layer 16 via a method
including, but not limited to, inkjet/laser printing, 3-D printing,
casting, extrusion, forging, plating (electroless, electro), plasma
spraying, aerosol spraying, thermal spraying, dip coating,
roll-to-roll coating, spin coating, spray coating, chemical
solution deposition, thermal evaporation, pulsed laser deposition,
cathodic arc deposition, or known etching techniques (i.e. sputter,
Chemical Vapor Deposition, Physical Vapor Disposition, Atomic Vapor
Disposition, ALD, or combination of deposition and thermal growth),
conversion coating, ion beam mixing, thin film printing, or may be
formed another way. The process for applying the conductive layer
18 may be selected to enhance permeability of a monitored compound
to the non-conductive layer 16, such with a vapor deposition
process. In a number of variations, the at least one lead 22 may
include a conductor such as a metal material, and may be used to
measure resistance or impedance in an area of interest. In a number
of variations, the at least one lead 22 may include a metal
including, but not limited to, plastic steel, stainless steel,
copper, nickel, tin, gold, silver, molybdenum, palladium, tungsten,
graphite or another form of carbon, zinc, iron, bronze, aluminum,
titanium, platinum, silicide, or may be another type), metallic
alloys, combinations thereof, or may be another type. In a number
of variations, the at least one lead 22 may be a combination of
materials in any amount or concentration. In a number of
variations, the at least one lead 22 may include a composite layer
comprising several layers of materials. In a number of variations,
the at least one lead 22 may be formed on or overlying the
conductive layer 18, or otherwise in contact therewith (such as
being formed on the non-conductive layer 16), via a method
including, but not limited to, inkjet/laser printing, 3-D printing,
casting, extrusion, forging, plating (electroless, electro), plasma
spraying, thermal spraying, dip coating, roll-to-roll coating, spin
coating, spray coating, chemical solution deposition, thermal
evaporation, pulsed laser deposition, cathodic arc deposition, or
known etching techniques (i.e. sputter, Chemical Vapor Deposition,
Physical Vapor Disposition, Atomic Vapor Disposition, ALD, or
combination of deposition and thermal growth), conversion coating,
ion beam mixing, thin film printing, or may be formed another way.
In a number of variations, the at least one lead 22 may be attached
to the conductive layer 18, (or the non-conductive layer 16 with
electric coupling to the conductive layer 18 so as to have minimal
resistance there between), through an adhesive comprising at least
one of, silver paste, acrylonitrile, cyanoacrylate, acrylic,
resorcinol glue, epoxy resin, epoxy putty, ethylene-vinyl acetate,
phenol formaldehyde resin, polyamide, polyester, polyethylene,
polypropylene, polysulfides, polyurethane, polyvinyl acetate,
polyvinyl alcohol, polyvinyl chloride, polyvinyl chloride emulsion,
polyvinylpyrrolidone, rubber cement, silicone, combinations
thereof, or may be another type. In the case of attachment of the
lead(s) 22 to the conductive layer 18, the adhesive may be selected
to be electrically conductive to make good ohmic contact. In a
number of variations as shown in FIGS. 1 and 3, the leads may be
provided individually, or in pairs with the same or different
spacing. For example a first pair may have a spacing that
represents a distance 21 between the leads 22 and a second pair may
have a second spacing of a distance 23 that may have a greater
distance between the leads 22. The distances 21, 23 may span areas
of interest for monitoring changes in opposition to current as a
strain gauge. Spacing of the leads 22 may be modulated to decouple
thermal and mechanical responses in providing spatial resolution.
For example, for a substrate 12 of a known material the coefficient
of thermal expansion (CTE), will be known. Deformation due to
temperature changes may be factored into the evaluation through a
calibration approach. If when monitoring the resistance/reactance
change at 4 set of leads 22 of varying spacing and the changes all
fall on the same calibration curve for CTE, then it may be
concluded that a temperature rise in the substrate 12 has occurred.
If however, one set of leads 22 shows a resistance/reactance change
that departs from the predefined calibration curve for CTE, then an
inference may be drawn that a deformation event associated with a
change in state of charge or state of health, such as where the
substrate is a battery pouch in the pouch. The spatial resolution
may be used in diagnostics, such as to identify a defective portion
of a cell through evaluating differences in sensed deformation.
[0035] In a number of variations, the sensor device 14,
non-conductive layer 16, and/or conductive layer 18 may operate as
a strain gauge. In a number of variations, the sensor device 14,
non-conductive layer 16, and/or conductive layer 18 may be used to
operate as a strain gauge to measure a variable by measuring
deformation of the substrate to which the sensor device 14 may be
mounted, and/or of the non-conductive layer 16, or change in
resistance of the conductive layer 18 through at least one
calculation. In a number of variations, the use of multiple leads
22 may be used to pinpoint a location of deformation, wherein
different changes may be detected through different leads at known
locations. In a number of variations, the sensor device 14,
non-conductive layer 16, and/or conductive layer 18 may be used to
operate as a strain gauge to measure compounds such as volatile
organic compounds (VOC's) in vapor state by measuring deformation
of the substrate to which the sensor device may be mounted and/or
non-conductive layer 16, or change in resistance/reactance of the
conductive layer 18. In a number of variations, the VOC's may
include, but are not limited to, aromatic and aliphatic
hydrocarbons, ketones, imides, amides, mercaptans or aldehydes, or
maybe another compound. The sensor device 14 provides the ability
to detect VOCs in low concentrations through deformation induced by
VOC ab(d)sorption in an electrically insulating polymer
--non-conducting layer 16. The deformation may be detected by
measuring changes in resistance or impedance of the conductive
coating and/or of the non-conducting layer 16. Direct current may
be used, and alternating current is an alternative. The polymer
non-conducting layer 16 may absorb/adsorb the organic gas phase
compounds causing micro swelling and elastic deformation. The
resulting strain may modify the conduction paths of the conductive
layer 18 resulting in a measurable resistance or impedance
change.
[0036] An ability to discriminate to analytes of choice, in the
sensor device 14 with a rapid response, reversibility and high
sensitivity may be provided, along with an ability to operate in
environments with humidity/water. The non-conductive layer 16 may
advantageously desorb water that has been absorbed, reversibly. In
a number of variations fluorinated polymers that may be highly
hydrophobic may be used for the non-conductive layer 16, or
portions thereof, as a way of differentiating between high humidity
and high VOC levels. Use of a fluorinated polymer may inhibit
absorption of water. For example, the non-conductive layer 16 may
be composed of PVDF, PTFE, PCTFE, FEP, ETFE, ECTFE, or another
polymer with hydrophobic properties. This is advantageous since it
increases the already existing ability of sensors device 14 to
perform without a need to be shielded from water. In a monitoring
application, multiple sensor devices 14 may be used, one of which
may include a fluorinated polymer as the non-conductive layer 16.
If the nonfluorinated sensor devices 14 are triggered it may be due
to VOC or humidity. If the fluorinated sensor device 14 is not
triggered while the nonfluorinated ones are, the cause may be
concluded to be a rise in humidity. If both the fluorinated and
nonfluorinated sensor devices 14 are triggered the cause can be
concluded to be a rise in VOC concentration. In a number of other
variations, the materials for the non-conductive layer 16 of the
sensor devices 14 may be selected so that their VOC response is
comparable but their response to humidity is measurably
different.
[0037] FIG. 5 illustrates a relation of VOC concentration to
resistance measured in the conductive layer 18 according to a
number of variations wherein the non-conductive layer 16 comprises
PMMA and the conductive layer 18 comprises a graphite spray
coating. The resistance change in Ohms of the sensor device 14 is
shown on the vertical axis as a function of analyte vapor
concentrations presented in parts per million on the horizontal
axis. Proportional responses are demonstrated for acetone at curve
26, methanol at curve 27 and xylene at curve 28. The demonstrated
response for xylene is relatively very high, and by extrapolation,
the detection limit for this particular compound can be in the
single PPM to 100's of PPB range. The other compounds have a lower
effect on the sensor device 14 and may reflect either a weaker
affinity of the VOC for the polymer or the smaller molecules may
cause a smaller amount of swelling even for the same moles of gas
absorbed into the sensor. In this example, data collected from the
sensor device 14 may be used to discern the presence of xylene,
acetone and/or methanol in the same environment, or to tailor the
sensor device 14 to discern xylene at very low concentrations.
Other polymers may be selected for other VOCs for example, PMMA may
exhibit greater sensitivity to polar compounds while PE/PP may
exhibit greater sensitivity to nonpolar species. The affinity of
the analyte for the polymer can be understood by the partition
coefficient relationship between the gas and solid phase (absorbed
into sensor), which can be expressed as:
K=CsCg=RT.rho..sub.1M1.gamma..sub.2P.sub.2 Where K is the partition
coefficient, Cs and Cg is analyte concentration in the polymer (Cs)
and gas (Cg) phase, respectively, .rho..sub.1 and M1 are the
density and molecular mass of the polymer and .gamma..sub.2 and
P.sub.2 are the activity coefficient and saturation vapor pressure
of the analyte, respectively. Where the fractional resistance
increase (.DELTA.R), is linear with fractional mass uptake in the
sensor such that .DELTA.R=kiCs where ki is a constant. then we can
combine this with the equation for the partition coefficient to
obtain: log 1/Cg=log 1/P.sub.2+log ki/.gamma..sub.2+log
RT.rho..sub.1/M1.DELTA.R and therefore, the slope of the log of the
inverse analyte gas phase concentration and the log of the inverse
of its saturation partial pressure yield the values for
ki/.gamma..sub.2. This response enables determining for example,
that xylene is present in the environment around the sensor device
14.
[0038] FIG. 6 illustrates a response of the sensor device 14 for a
stimulus from a VOC with resistance in ohms on the vertical axis as
a relative response. R.sub.baseline+R.sub.measurement and time in
milliseconds on the horizontal axis. In a number of variations,
spikes in the measured resistance, as illustrated as spike 29 in
FIG. 6 for example, may indicate a change or increase in presence
of VOC's while rate of change in the resistance may indicate a
change in the source generating the VOC. For example, the sensor
device 14 may be exposed to acetone introduced to the sensing
device 14 in the presence of air flow. A measured resistance of
greater than the baseline of approximately 10 ohms may indicate the
presence of acetone in the environment, while the rapid change from
the baseline to the peak 29 may indicate an underlying change in
the operation being monitored, where the changes results in the
generation or release of additional acetone from a norm. As
demonstrated, the sensor device 14 responds to the introduction of
analytes quickly and returns to the baseline resistance after the
exposure demonstrating a rapid and reversible response. As can be
seen the signal to noise of the response is very good and the
response nearly instantaneous. Return to the baseline within
seconds demonstrates that very small and quick changes in
environmental quality can be detected readily.
[0039] In a number of variations as illustrated in cross section in
FIG. 7, the product may include the non-conductive layer 16 and the
conductive layer 18. The conductive layer 18 may have a surface 30
in contact with the non-conductive layer 16 at its surface 31. The
lead(s) 22 may be provided on the surface 32 of the conductive
layer 18, opposite the surface 30. The leads 22 may be provided in
a series of conductive micro-structure elements (e.g. 34, 36, 38,
etc.), that may be applied to the surface 32. The micro-structure
elements 34, 36, 38, may be made of any of the materials listed
above for the leads 22, or any material sufficient to conduct
current for sensing purposes. The micro-structure elements 34, 36,
38 may be selected as leads 22 to increase sensitivity of the
sensor device 14, and/or to pinpoint deformation changes. In a
number of variations, the leads 22 may be placed at the surfaces
30, 31 between the nonconductive layer 16 and the conductive layer
32, as shown in FIG. 8. In a number of variations the leads 22 may
be embedded in the non-conductive layer 16, but still in electrical
communication with conductive layer 18 as shown in FIG. 9. In this
case the leads 22 may be adjacent the surface 32 and may preferably
be in contact with the conductive layer 18, or may otherwise be
electrically coupled therewith. In a number of variations as shown
in FIG. 10, the leads may be applied to the surface 31, of the
non-conductive layer 16, or may be embedded therein as shown in
FIG. 9, and the conductive layer may be omitted. In such a case,
the presence of the micro-structures 34, 36, 38, on or in the
non-conductive layer 16 may support monitoring by measuring changes
in capacitance over gaps between the leads 22. The micro-thread
approach may support exclusion of the conductive layer 18, although
embedding in the non-conductive layer 16 may result in less
sensitivity The micro-structures 34, 36, 38, may be provided as
linear threads, non-linear threads, tubes, or other structures
applied to the surface of, or embedded in the non-conductive layer
16 or the conductive layer 18. In any of the variations of FIGS.
7-11, the leads 22 may be conductors such as shown in FIGS. 1 and
3. In a number of variations, the micro-structures 34, 36, 38 may
be formed in woven mesh creating a matrix as shown in FIG. 11,
(shown before application for clarity), or may otherwise be
distributed on, or interspersed in, the conductive layer 18. In a
number of variations the micro-structures 34, 36, 38 may be aligned
in a designed fashion with specified spacing, or may be randomly
arranged in forming the matrix. It should be understood that the
physical layout and dimensions of the sensor device 14 may be
provided in any shape suitable to the application where monitoring
is desired. For example, the sensor device 14 may be matched to the
shape of a mating substrate, may be cylindrical, may be a wire-like
shape, may be round, may be spherical, may be irregularly shaped,
or may be otherwise shaped.
[0040] With reference again to FIG. 3, in a number of variations,
the DAQ 24 or ECM 25 may receive and process input from at least
one sensor device 14 in light of stored instructions and/or data,
determine a variable through at least one calculation, and transmit
output signals to various receptors. The data acquisition module
(DAQ) 24 or electronic control module (ECM) 25 may include, for
example, an electrical circuit, an electronic circuit or chip,
and/or a computer. In an illustrative computer variation, the data
acquisition module (DAQ) 24 or electronic control module (ECM) 25
generally may include one or more processors, or memory storage
units that may be coupled to the processor(s), and one or more
interfaces electrically coupling the processor(s) to one or more
other devices, including at least one of the other of the data
acquisition module (DAQ) 24 or electronic control module (ECM) 25,
or to the at least one sensor device 14, or to a different
component of a vehicle. The processor(s) and other powered system
devices (including at least one of the other of the data
acquisition module (DAQ) 24, electronic control module (ECM) 25, or
to the at least one sensor device 14) may be supplied with
electricity by a power supply, for example, a generated and
distributed power source, a battery, other fuel cells, a vehicle
engine, other vehicle power component, or other source. The
processor(s) may execute instructions or calculations that provide
at least some of the functionality for the sensor device 14 and
methods 800, 900 (FIGS. 20 & 21). As used herein, the term
instructions may include, for example, control logic, computer
software and/or firmware, programmable instructions, or other
suitable instructions. The processor may include, for example, one
or more microprocessors, microcontrollers, application specific
integrated circuits, programmable logic devices, field programmable
gate arrays, and/or any other suitable type of electronic
processing device(s).
[0041] Also, in a number of variations, the data acquisition module
(DAQ) 24, or electronic control module (ECM) 25, may be configured
to provide storage for data received by or loaded to the at least
one of the other of the data acquisition module (DAQ) 24 or
electronic control module (ECM) 25, or to the at least one sensor
device 14, or to a different component of a vehicle, or the like,
for processor-executable instructions or calculations. The data,
calculations, and/or instructions may be stored, for example, as
look-up tables, formulas, algorithms, maps, models, and/or any
other suitable format. The memory may include, for example, RAM,
ROM, EPROM, and/or any other suitable type of storage article
and/or device.
[0042] In a number of variations, the interfaces may include, for
example, analog/digital or digital/analog converters, signal
conditioners, amplifiers, filters, other electronic devices or
software modules, and/or any other suitable interfaces. The
interfaces may conform to, for example, RS-232, parallel, small
computer system interface, universal serial bus, CAN, MOST, LIN,
FlexRay, and/or any other suitable protocol(s). The interfaces may
include circuits, software, firmware, or any other device to assist
or enable the data acquisition module (DAQ) 24 or electronic
control module (ECM) 25, in communicating with other devices.
[0043] In a number of variations as illustrated in FIG. 12, the
conductive layer 18 may be applied to less than the entire surface
31 of the non-conductive layer 16. The conductive layer 18 may be
applied in strips, geometric shapes, patterns, random places, or in
other shapes to leave exposed areas of the surface 31. For example,
as shown in FIG. 12, the conductive layer 18 may be applied in
patches, such as patches 41-44 so that areas such as gaps or areas
46-49 on the surface 31 may be exposed. Exposure of the surface 31
may increase the response of the non-conductive layer to an
exposure to a monitored compound. The leads 22 may be applied on
the patches 41-44 and may pass along the surface 31 in the areas
46-49. The leads may be connected with a power source 50 through
connectors 51, 52. The DAQ 24 may control and monitor the sensor
device, may collect information from the leads 22, may record the
information as data, and may communicate with the ECM 25.
Communication may be effected through a wired connection or a
wireless interface 53.
[0044] In a number of variations a semi-permeable layer 19 such as
PVC or low density PE (shown in FIG. 11), may be applied to the
sensor device 14 and/or the conductive layer may be formed of a
semi-permeable material such as carbon, or graphite, in each case
where the material may be chosen to allow the passage of selected
compounds and/or to inhibit the passage of select compounds. For
example, pore diameters in the membrane selected for the conductive
layer 18 may be larger than the largest molecular diameter that is
the target to be monitored, and may be on the same size as the mean
free path of the gas molecules. This may allow for the separation
of species that reach the non-conductive layer 16 by molecular
weight such that the rate of diffusion through the conductive layer
18 is inversely proportional to the square root of the molecular
weight. If the pore diameter is smaller than the mean free path of
the diffusing gas molecules and the density of the gas is low, the
gas molecules collide with the pore walls more frequently than with
each other. This Knudsen flow or Knudsen diffusion process and may
be selected when the monitored compound has a relatively large
molecule to pass through a 100 to 300 angstrom pore size conductive
layer 18. For medium sized molecules, a pore size in the range of
40 to 100 angstroms may be selected for the conductive layer 18
wherein the monitored compound may condense into these pores and
diffuse through Kelvin condensation to reach the non-conductive
layer 16. The material for the conductive layer 18 or coating may
be selected for molecular sieve permeation, which may be used with
a pore size distribution such that a monitored compound with
smaller molecules can diffuse into the pores to reach the
non-conductive layer 16 at the exclusion of larger molecules. By
selecting a material for the semi-permeable coating or for the
conductive layer 18, the non-conductive layer may be tailored to
respond to a monitored compound by molecular size.
[0045] In a number of variations an array of sensors may be used.
For example, the array may include a sensor device 54 with selected
different nonconductive polymers provided in the quadrants of the
nonconductive layer 16. For example, as shown in FIG. 13, the
quadrants 55-58 may be comprised of any of the polymeric materials
listed above for use in the non-conductive layer 16. Each of the
quadrants 55-58 may be comprised of a different one of those
polymeric materials. Each of the chosen polymeric materials may be
selected for their response to a selected compound of interest for
monitoring purposes. The quadrants 55-58 may have separate leads 22
for collecting information. The non-conductive layer 16 may be
coated with the conductive layer 18. In a number of variations
quadrants 55-58 may be provided as separate sensor devices that are
not attached together so that they may be dispersed to different
monitoring points. Providing multiple sensor quadrants or devices
with different polymers as the non-conductive layer 16, enhances
the ability to monitor for different compounds and/or to
discriminate between compounds, due to the ability to select
different polymers that respond differently. In VOC monitoring, the
sensor devices 14 in the array may be free of an underlying
substrate so as to increase surface area for absorbance of the
analyte(s) and/or to maximize sensitivity to the monitored
compounds. In other variations an array of sensor devices 14 may be
configured as shown in FIG. 14. The sensor array 57 may include a
plurality of such devices to improve discrimination between
monitored compounds. For example, the sensing devices 101-120 may
be arranged on a supporting substrate 121 to provide an index of
air quality. The index for example, may be categorized in any
number of ways depending on the purpose of monitoring. The
categories may be defined based on the type and quantity of VOC
present. By choosing the particular polymer for each of the
non-conducting layers 16 of the sensor devices 101-121, sensors
with affinities to different monitored compounds may be included.
By selecting the polymers for the non-conductive layers 16 based on
their affinity to certain compounds, the type of compound providing
a stimulus to the array may be discerned. Each of the sensing
devices 101-120 may have an independent pair of leads 22 on the
conductive layer 18 for monitoring each non-conductive layer 16
individually. An analysis of the array may involve N resistance
readings resulting in resistance changes for the sensor devices
101-120, where the relative resistance changes of the sensor
devices 101-120 may be a diagnostic indicative of a stimulus such
as VOC presence, deformation, strain, etc. Complex mixtures of
analytes may be further distinguished using vapor pressure data for
the monitored compounds as related to reaching a full resistance
change in a sensor device at saturation.
[0046] FIG. 15 illustrates responses of the sensor device 14 as a
function of time for 0.5 microliters of xylene injected into a 100
ml vessel at curve 60, and for 5 microliters of acetone into the
same volume at curve 62. Analyte concentrations for the two VOCs
are identical and the varied response is due to differing
affinities between the non-conducting layer 16 and the analyte.
Resistance in kiloohms is plotted on the vertical axis and time in
seconds is plotted on the horizontal axis. The traces are plotted
together to demonstrate the difference in the magnitude and
temporal response of the sensor device 14 to the two analytes. In
each case the analyte was introduced at point 64. As demonstrated,
acetone has a much lower response in terms of resistance magnitude,
despite the introduction of a tenfold larger sample volume relative
to xylene. The rise time, defined as the time required to reach
one-half the saturation resistance response is much shorter for
acetone as compared to xylene. A factor influencing rise may be the
rate of diffusion of the analyte into the polymer non-conductive
layer 16. Other factors may include vapor pressure and diffusion
coefficient of the analyte, which may impact transport rate to the
sensor device 14. Since diffusion into the polymer influences rise
time, monitoring, measuring and processing rise time can be used to
distinguish between VOC analytes. For the rapidly rising portion of
the curve 62, response can be represented by:
M(t)/M(.infin.)=2(Dt/.pi.L2).sup.0.5 where M(t) and M(.infin.) are
the mass uptake by the non-conductive layer 16 at time t and an
equilibrium mass uptake, respectively. L is the thickness of the
non-conductive layer and D is the diffusion coefficient. For
analytes of different molecular weights, response rise time for
analyte diffusion into the non-conductive layer 16 may be monitored
and determined. This may include determining the rise time between
a baseline at 64 and a peak 63, and may include determining the
magnitude of the peak 63 to determine the type of VOC sensed based
its molecular weight. FIG. 15 demonstrates a correlation between
the time needed to reach full saturation at the peaks and the vapor
pressure of the analyte, with curve 62 for acetone with a vapor
pressure of 30 kPa and curve 60 for xylene with vapor pressure of
2.0 kPa.
[0047] With reference to FIG. 16, illustrated is a response of the
sensor device 14 as demonstrated by curves 73 and 75 to two
different injection volumes of tetrahydrofuran (THF). Resistance in
kiloohms is plotted on the vertical axis and time is seconds is
plotted on the horizontal axis. The injected volume was greater for
curve 75 resulting in an approximate vapor concentration of 2900
PPM from a 1.0 microliter injection than for curve 73 resulting in
an approximate vapor concentration of 1160 PPM from an injection of
0.4 microliter. The response is demonstrated as correlative or
proportional to the amount of analyte injected. As a result the
data collected from the sensor device 14 may be correlated to the
concentration of VOC analyte in the environment around the sensor
device 14. FIG. 17 demonstrates a correlative/proportional response
of three analytes. Resistance is graphed on the vertical axis as a
percentage determined by (measured resistance R over initial
resistance R-1) times 100. Vapor concentration in parts per million
is graphed on the horizontal axis. Curve 76 plots the response of
the sensor device 14 to increasing concentrations of xylene and
demonstrates an increasing resistance change correlating to an
increase in concentration. Curve 77 plots the response of the
sensor device 14 to increasing concentrations of acetone and
demonstrates an increasing resistance change correlating to an
increase in concentration, but with a lower slope than xylene.
Curve 78 plots the response of the sensor device 14 to increasing
concentrations of pentane and demonstrates an increasing resistance
change correlating to an increase in concentration, with yet a
lower slope than acetone.
[0048] With reference to FIG. 18, resistance is graphed on the
vertical axis as a proportion of R.sub.measured over R.sub.initial
and time in milliseconds is graphed on the horizontal axis.
Different volumes of acetone were injected into an argon
environment containing the sensing device 14, with the environment
experiencing a flow of 1150 cc/minute. Curve 79 demonstrates the
response of the sensor device 14 after the injection of 0.2
microliters of acetone. Curve 80 demonstrates the response of the
sensor device 14 after the injection of 1.0 microliters of acetone.
Curve 81 demonstrates the response of the sensor device 14 after
the injection of 2.0 microliters of acetone. Curve 82 demonstrates
the response of the sensor device 14 after the injection of 5.0
microliters of acetone. Each of the curves 79-82 demonstrates the
rapid response of the sensor device 14 following the injection
point 83. Each of the curves 79-82 also demonstrates the recovery
of the sensor device 14 as the compounds are desorbed from the
non-conductive layer 16. In FIG. 19, the curve 65 also demonstrates
the rapid response 69, 70 of the sensor device 14 to the
introduction of an analyte, and the rapid recovery 71, 72 of the
sensor device 14 to near baseline 74. As a result, the sensor
device 14 may be used to detect an increased concentration of a VOC
and the ECM 25 may be programmed to response to different
concentrations in different manners. Once the VOC concentration
diminishes, the sensor device's response reverses for ongoing
monitoring.
[0049] In a number of variations, the methods or parts thereof may
be implemented in a computer program product including instructions
or calculations carried on a computer readable medium for use by
one or more processors to implement one or more of the method steps
or instructions. The computer program product may include one or
more software programs comprised of program instructions in source
code, object code, executable code or other formats; one or more
firmware programs; or hardware description language (HDL) files;
and any program related data. The data may include data structures,
look-up tables, or data in any other suitable format. The program
instructions may include program modules, routines, programs,
objects, components, and/or the like. The computer program may be
executed on one processor or on multiple processors in
communication with one another.
[0050] In a number of variations, the program(s) can be embodied on
computer readable media, which can include one or more storage
devices, articles of manufacture, or the like. Illustrative
computer readable media include computer system memory, e.g. RAM
(random access memory), ROM (read only memory); semiconductor
memory, e.g. EPROM (erasable, programmable ROM), EEPROM
(electrically erasable, programmable ROM), flash memory; magnetic
or optical disks or tapes; and/or the like. The computer readable
medium also may include computer to computer connections, for
example, when data may be transferred or provided over a network or
another communications connection (either wired, wireless, or a
combination thereof). Any combination(s) of the above examples is
also included within the scope of the computer-readable media. It
is therefore to be understood that the method may be at least
partially performed by any electronic articles and/or devices
capable of executing instructions corresponding to one or more
steps of the disclosed methods.
[0051] In a number of variations, as shown in FIG. 20, a method 800
is shown. In a number of variations, the method 800 may include a
step 802 of providing a substrate. The method 800 further includes
step 804 of providing a non-conductive layer 16 and overlying the
substrate with the non-conductive layer 16, or mounting the
non-conductive layer on the substrate. The method 800 may further
include step 806 of providing a conductive layer 18 and overlying
the non-conductive layer 16 with the conductive layer 18 to form a
sensor device 14 constructed and arranged to measure or monitor at
least one variable of the substrate, or the environment around the
non-conductive layer 16. In a number of variations, as shown in
FIG. 21, a method 900 is shown. The method 900 may include a step
902 of providing a substrate. The method 900 may further include
step 904 of providing a sensor device 14 electronically coupled to
the substrate comprising a non-conductive layer 16 and a conductive
layer 18 overlying the non-conductive layer 16 constructed and
arranged to measure or monitor at least one variable comprising at
least one of temperature, pressure, volatile organic compound
concentration, state of charge, or state of health of a substrate.
The method 900 further includes step 906 of determining at least
one of deformation of the non-conductive layer 16 or the substrate,
or change in resistance of the conductive layer 18 to provide
measurement or monitoring of the at least one variable based on at
least one calculation.
[0052] In a number of variations as illustrated with the assistance
of FIG. 22, a method 950 may include the step 952 of providing a
non-conductive layer 16. In a number of variations the
non-conductive layer 16 may be provided in step 952 as one
contiguous structure comprised of one non-conductive polymer. In a
number of variations the non-conductive layer 16 may be provided in
step 952 as one contiguous structure comprised of multiple
different non-conductive polymers, such as in quadrants 55-58. In a
number of variations the non-conductive layer 16 may be provided in
step 952 as an array of separate structures, each comprised of one
non-conductive polymer, or each comprised of one or more different
non-conducting polymers. In a number if variations in step 952, a
polymer with hydrophobic properties may be used for the
non-conductive layer 16 as a way of differentiating between
humidity and VOC presence. The method 950 may include the step 954
of providing a conductive layer 18 that may overlie, or may
otherwise be in contact with, the non-conductive layer 16. In step
954 the conductive layer 18 may be constructed and arranged to
measure or monitor at least one variable in the non-conducting
layer 16. In a number of variations in step 954, the conductive
layer 18 may cover the surface 31 of the non-conductive layer 16,
substantially completely, or may completely cover the surface 31.
In a number of variations the conductive layer 18 may be provided
in step 954 over only a part of the surface 31. For example, the
conductive layer 18 may be applied so that areas 46-49 may be
uncovered spaces on the surface 31 between areas of the conductive
layer 18, such as by applying the patches 41-44. The method 950 may
include the step 956 of providing a number of lead(s) 22 to support
monitoring at least one variable of the sensor device 14. In a
number of variations the lead(s) may be connected in step 956 to a
power source 50. In a number of variations in step 956, the lead(s)
22 may be formed on or overlying the conductive layer 18. In a
number of variations the lead(s) may be provided in step 956 in
differently spaced pairs. In a number of variations the leads 22
may be located between the conductive layer 18 and the
non-conducting layer 16 in step 956. In a number of variations the
lead(s) 22 may be formed on or overlying the non-conductive layer
16 in step 956. In a number of variations in step 956, the lead(s)
22 may be embedded in the non-conductive layer 16, or the
conductive layer 18. In a number of variations in step 956, the
lead(s) 22 embedded in the non-conductive layer 16 may be in
contact with the conducting layer 18. In a number of variations in
step 956, the lead(s) 22 may be formed as spaced aligned individual
leads. In a number of variations the leads 22 may be formed as a
mesh in step 956. In a number of variations in step 956, the
lead(s) 22 may be formed as a distributed structure according to a
pattern or randomly. The method 950 may include the step 958 of
providing a mechanism to monitor the response of the non-conductive
layer 16, which may include providing the DAQ 24. In a number of
variations in step 958, the DAQ 24 may be connected with the
lead(s) 22 to collect information. In a number of variations in
step 958, the lead(s) 22 may be connected directly to the ECM 25 to
collect information. In a number of variations in step 958, the DAQ
may be in communication with the ECM 25 through a wireless
connection. In a number of variations in step 958, the DAQ 24 may
monitor for resistance or impedance changes between a pair of leads
22. The method 950 may further include the step 960 of determining
a deformation of the non-conductive layer 16 by monitoring for a
change in resistance between the lead(s) 22 to provide measurement
or monitoring of a VOC in the environment surrounding the sensing
device 14. In a number of variations the step 960 may include
determining the type of VOC sensed, such as by comparing the
magnitude and/or the rate of the resistance change to known
resistance changes for different types of VOCs, such as through a
lookup table reference. In a number of variations the step 960 may
include determining the concentration of VOC sensed, such as by
comparing the magnitude of the resistance change to known
resistance changes for different types of VOCs, such as through a
lookup table reference. In a number of variations the step 960 may
include monitoring for a change in an operation or an environment,
where the changes results in the generation or release of
additional VOC. For example, the normal presence of a varying
amount of analyte may be accompanied by a rate of change indicative
of an abnormal event. In a number of variations step 960 may
include determining the rise time between a baseline at 64 and a
peak 63, and may include determining the magnitude of the peak 63
to determine the type of VOC sensed based its molecular weight.
[0053] Referring again to FIG. 3, in a number of variations, the
non-conductive layer 16 and/or conductive layer 18 of the sensor
device 14 may be used to operate as a PTC thermocouple to measure
temperature of a substrate to which the sensor device 14 may be
mounted or the area in close proximity to the sensor device 14
through at least one calculation. In a number of variations, the
sensor device 14 may cover the entirety of a substrate to which it
may be mounted and may act as a grid-like system of interconnected
sensor devices 14 to provide inputs to determine variables at a
number of locations to provide local and overall variable
(including, but not limited to, temperature, pressure, or volatile
organic compound concentration) measurement and monitoring through
at least one calculation. In a number of variations, placement of a
plurality of sensor devices 14 onto various locations on or in
close proximity to a substrate may decouple the deformation
measurements of the substrate and/or non-conductive layer 16 to
provide more accurate measurement and monitoring on deformation
related to SOC or SOH versus deformation related to the presence of
VOC's. In a number of variations, this may allow the sensor device
14 or plurality of sensor devices 14 to measure the presence of
VOC's in relation to the substrate independent of the state of
charge or state of health measurements of the substrate. In a
number of variations, placement of a plurality of sensor devices 14
onto various locations on or in close proximity to a substrate may
decouple the deformation measurements of the substrate and/or
non-conductive layer 16 to provide more accurate measurement and
monitoring on deformation related to SOC or SOH versus deformation
related to the temperature or pressure. In a number of variations,
temperature or pressure may be indicated through deformation
measurements of the substrate and/or non-conductive layer 16 via a
calculation and may be measured independent of SOC or SOH
measurement through the use of the PTC thermocouple.
[0054] As detailed above, the sensor device 14 may have multiple
advantages including superior long term stability of the sensor
element since the polymer's chemical reactivity to the ambient
environment is decoupled from the transduction mechanism through
inclusion of the conductive layer 18, a faster response, and a
higher degree of reversibility since the transduced signal does not
rely on a chemical interaction between the polymer and analyte. Use
of the non-conducting layer 16 supports performance without a need
to be shielded the sensor device 14 from water and oxygen since the
polymer will not degrade over time with exposure to them. The
sensor device 14 may be used for analyte detection, identification,
classification, and/or tracking through a polymer non-conducting
layer 16 with conductive layer 18 that may be provided as a coating
on the non-conducting layer 16. Electrical resistance or impedance
changes may be used for analyte detection and classification.
Signal processing for the detection, identification, classification
and/or tracking of a narrow band of likely analyte. Tuning
sensitivity for a specific analyte may be accomplished by altering
the composition of the non-conductive layer 16. For example, PMMA
may be used due to its sensitivity to polar compounds while PE or
PP may be used due to their sensitivity to nonpolar species. An
array of sensors with unique response to individual analyte may be
used for classifications. Examples of uses of the products and
methods described herein may include food quality inspection,
pharmaceutical processing, chemical synthesis, beverage processing,
monitoring for health purposes, cosmetic production, manufacturing
plant monitoring, vehicle interior air quality, residential air
evaluation, vehicle shed testing, or any application where the
monitoring, detection, identification, classification, and/or
tracking of analytes is desired. Specific uses may involve
employing an array of multiple detectors with differing polymer
composition as the non-conductive layer to discriminate between
emissions from adhesives or polymer components in a vehicle or a
fuel or oil source during a vehicle sealed housing evaporative
determination (SHED), test. Another use may involve diagnosis of
welding tips by evaluating the gases resulting from a welding
process where a depleted weld tip releases different VOCs than a
non-depleted weld tip.
[0055] The following description of variants is only illustrative
of components, elements, acts, product and methods considered to be
within the scope of the invention and are not in any way intended
to limit such scope by what is specifically disclosed or not
expressly set forth. The components, elements, acts, product and
methods as described herein may be combined and rearranged other
than as expressly described herein and still are considered to be
within the scope of the invention.
[0056] Variation 1 may involve a product for sensing that may
include a non-conductive layer of a polymer that may be selected
for its responsiveness to a stimulus from one of a selected analyte
or a selected group of analytes. The non-conductive layer may be
non-conductive of an electrical current. A conductive layer may be
in contact with the non-conductive layer and may be conductive of
the electrical current. A lead may provide an electric current to
the conductive layer. A device may be provided to detect at least
one property of the conductive layer in response to the
stimulus.
[0057] Variation 2 may include the product according to variation 1
wherein the conductive layer may be in contact with a surface of
the non-conductive layer and may cover only a portion of the
surface so that an area of the surface may be exposed directly to
the stimulus.
[0058] Variation 3 may include the product according to variation 1
wherein the non-conductive layer may be comprised of areas of
different polymers having different responses to the stimulus.
[0059] Variation 4 may include the product according to variation 3
wherein the areas may be part of one contiguous structure.
[0060] Variation 5 may include the product according to variation 1
wherein the lead may include at least a first pair of leads and a
second pair of leads. The first pair of leads may be spaced from
each other at a first distance. The second pair of leads may be
spaced from each other at a second distance that may be greater
than the first so that the first and second pairs of leads
communicate a different response to the stimulus.
[0061] Variation 6 may include the product according to variation 1
wherein the device may include a data acquisition module that may
be in communication with the lead to collect information on
responses to the stimulus.
[0062] Variation 7 may include the product according to variation 1
wherein the lead may be applied to the conductive layer.
[0063] Variation 8 may include the product according to variation 1
wherein the lead may be disposed between the conductive layer and
the non-conductive layer.
[0064] Variation 9 may include the product according to variation 1
wherein the lead may be a number of spaced apart leads.
[0065] Variation 10 may include the product according to variation
1 and may include a semi-permeable layer overlying one of the
non-conductive layer or the conductive layer. The semi-permeable
layer may have a pore size selected to pass the selected analyte or
the selected group of analytes.
[0066] Variation 11 may involve a method of monitoring for an
exposure to an analyte. A sensing device may be provided with a
non-conductive layer. A lead structure may be provided to apply a
current to a zone of the sensing device that exhibits an opposition
to the current. The opposition may varies in response to the
exposure of the non-conducting layer to the analyte.
[0067] Variation 12 may include the method according to variation
11 and may include providing a device to monitor changes in the
opposition to electrical current. The changes may be processed. A
rate of change of the opposition may be determined. A magnitude of
change in the opposition may be determined. The rate of change and
the magnitude of change may be compared to classify the
analyte.
[0068] Variation 13 may include the method according to variation
11 and may include providing the non-conductive layer as a polymer
that does not conduct the current. A conductive layer may be
applied to the non-conductive layer, the conductive layer may
conduct the current.
[0069] Variation 14 may include the method according to variation
13 and may include providing the lead structure electrically
coupled with the conductive layer. The zone may be provided in the
conductive layer. The response of the non-conductive layer to the
exposure to the analyte may be measured by evaluating changes in
the opposition.
[0070] Variation 15 may include the method according to variation
14 and may include allowing the non-conductive layer to expand in
response to the exposure to the analyte so that the opposition
changes in the zone as a result of the expansion.
[0071] Variation 16 may include the method according to variation
11 and may include providing the non-conductive layer as an array
of different polymers selected to have different responses to the
exposure to the analyte.
[0072] Variation 17 may include the method according to variation
11 and may include providing a conductive layer overlying a surface
of the non-conductive layer with areas of the surface exposed and
not covered by the conductive later to tune the sensitivity of the
sensing device to the analyte.
[0073] Variation 18 may include the method according to variation
11 and may include discerning between the analyte and water vapor
by providing the non-conductive layer as a fluorinated polymer.
[0074] Variation 19 may include the method according to variation
11 and may include classifying the analyte by comparing a magnitude
and a rate of the opposition change to known opposition changes for
different types of analytes.
[0075] Variation 20 may include the method according to variation
11 and may include quantifying a concentration of the analyte by
determining a magnitude of change in the opposition and comparing
the magnitude to known magnitudes of change for different
concentrations of the analyte.
[0076] The above description of select variations within the scope
of the invention is merely illustrative in nature and, thus,
variations or variants thereof are not to be regarded as a
departure from the spirit and scope of the invention.
* * * * *