U.S. patent application number 12/739362 was filed with the patent office on 2011-07-28 for system and method for detection of foreign substances.
This patent application is currently assigned to M.S. Tech Ltd.. Invention is credited to Lev Dayan, Vladimir Sergeyev, Moshe Shalom, Vitaly Strokhin.
Application Number | 20110184397 12/739362 |
Document ID | / |
Family ID | 40580184 |
Filed Date | 2011-07-28 |
United States Patent
Application |
20110184397 |
Kind Code |
A2 |
Dayan; Lev ; et al. |
July 28, 2011 |
System and Method for Detection of Foreign Substances
Abstract
A sensing unit is presented for use in identifying at least one
foreign substance in a region of interest. The sensing unit
comprises at least one measurement unit, which comprises one or
more sensor elements each configured and operable to be responsive
to at least one foreign substance in the vicinity thereof. Each
sensor element is mounted in its own compartment having an inlet
and an outlet thus defining an environmental region in the vicinity
of the sensor element separated from the surroundings of the
compartment.
Inventors: |
Dayan; Lev; (Ramat Sharet,
IL) ; Shalom; Moshe; (Herzeliya, IL) ;
Strokhin; Vitaly; (Beer-sheva, IL) ; Sergeyev;
Vladimir; (Rehovot, IL) |
Assignee: |
M.S. Tech Ltd.
5 Keret Street
Herzlyia
IL
46411
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20100305556 A1 |
December 2, 2010 |
|
|
Family ID: |
40580184 |
Appl. No.: |
12/739362 |
Filed: |
October 25, 2007 |
PCT Filed: |
October 25, 2007 |
PCT NO: |
PCT/IL2007/001285 |
371 Date: |
April 22, 2010 |
Current U.S.
Class: |
606/20 |
Current CPC
Class: |
G01N 2291/0257 20130101;
G01N 33/0057 20130101; G01N 29/036 20130101 |
Class at
Publication: |
606/020 |
International
Class: |
A61B 18/02 20060101
A61B018/02 |
Claims
1. A sensing system for use in identifying at least one foreign
substance in a region of interest, the sensing system comprising a
certain number of sensor units, the sensor unit comprising at least
one measurement unit including one or more sensor elements
configured and operable to be responsive to at least one foreign
substance in the vicinity thereof and to generate a response signal
indicative thereof, the sensor element being mounted in its own
compartment having an inlet and an outlet thus defining an
environmental region in the vicinity of the sensor element
separated from the surroundings of the compartment.
2. The sensing system of claim 1, wherein the measurement unit
comprises an array of at least two said sensor elements, each
sensor element being mounted in its own separate compartment having
the inlet and outlet thus defining the environmental region in the
vicinity of the sensor element separated from the surroundings of
the compartment and from at least one other compartment containing
at least one other sensor element.
3. The sensing system of claim 1, comprising at least two sensor
units.
4. The system of claim 1, comprising a control system connectable
to the sensor unit for receiving and analyzing the response signal
and generating output signal indicative thereof.
5. The system of claim 2, wherein the compartments are arranged
within the measurement unit in a spaced-apart relationship.
6. The system of claim 2, wherein the compartments are arranged
within the measurement unit in a spaced-apart relationship along a
circular path
7. The system of claim 1, comprising a feeding unit configured and
operable for providing an input flow of a sample medium from the
region of interest towards and through the measurement unit.
8. The system of claim 1, wherein the sensor unit comprises a
feeding unit configured and operable for providing an input flow of
a sample medium from the region of interest towards and through the
measurement unit.
9. The system of claim 2, wherein the compartments are arranged
within the measurement unit in a spaced-apart relationship along a
circular path.
10. The system of claim 7, wherein the compartments are arranged
within the measurement unit in a spaced-apart relationship along a
circular path, the sample medium being concurrently supplied to all
the compartments
11. The system of claim 2, wherein the compartments are arranged in
a one-dimensional array.
12. The system of claim 7, wherein the compartments are arranged in
a one-dimensional array, the sample median being sequentially
supplied to all the compartments
13. The system of claim 7, wherein the sample feeding unit
comprises a suction assembly.
14. The system of claim 13, wherein the suction assembly comprises
a first pump-like unit connected to an outlet of the measurement
unit
15. The system of claim 14, wherein the suction assembly comprises
a second pump-like unit interconnected between the region of
interest and an inlet of the measurement unit.
16. The system of claim 15, wherein the first and second pump-like
units are operable synchrony to provide a desired flow of the
sample medium through the measurement unit.
17. The system of claim 7, wherein the feeding unit comprises a
sample preparation unit connectable to the sensor unit.
18. The system of claim 7, wherein the feeding unit comprises a
sample preparation unit connectable to the measurement unit.
19. The system of claim 7, wherein the sample preparation unit is
configured as a separator for separating and filtering out a
purified air medium and collecting particles from the sample medium
and flowing the collected particles to the measurement unit.
20. The system of claim 7, wherein the sample preparation unit
comprises a pre-concentrate for collecting the sample medium, and a
heating unit for heating the sample medium.
21. The system of claim 1, comprising a heating unit configured for
heating the sample medium while flowing towards the measurement
unit.
22. The system of claim 1, comprising a heating unit configured for
heating inner surfaces of the sensor unit to prevent adsorption of
the sample medium thereon.
23. The system of claim 1, wherein the sensor unit is a two-unit
assembly configured to enable operation of one sensor unit during
regeneration of the other.
24. The system of claim 1, configured for identifying one or more
substances in a liquid medium.
25. The system of claim 1, comprising a lift-like assembly
associated with the measurement unit for moving the measurement
unit into and out of the liquid medium.
26. The system of claim 7, configured for identifying one or more
substances in a liquid medium.
27. The system of claim 26, wherein the sensor unit comprises two
measurement units configured such that the first measurement unit
is located outside the liquid medium during the system operation
and is capable of identifying one or more foreign substances in a
vapor coming from said liquid medium, and the second measurement
unit is driven for movement into and out of the liquid medium and
is capable of identifying one or more foreign substances in the
liquid medium.
28. The system of claim 4, wherein the compartments with the sensor
elements are equally distanced from an actuator utility of the
control system.
29. The system of claim 28, wherein the compartments are arranged
in a spaced-apart relationship along a circular path, the actuator
utility being located on a central axis of the circle.
30. The system of claim 29, comprising a disc formed with a
circular array of the compartments with the sensor elements, the
control system comprising an actuator utility located in the center
of the disc.
31. The system of claim 1, wherein the sensor element is a
piezoelectric crystal resonator characterized by a certain
resonance frequency value and carrying reactive molecules of a kind
capable of interacting with said at least one foreign material to
yield a reaction product that effects a change in the resonance
frequency of said crystal resonator from said certain resonance
frequency value, said change being indicative of the identity of
said at least one foreign material.
32. The system of claim 31, wherein said piezoelectric crystal
resonator is configured as an inverted mesa structure having a
membrane-like region.
33. The system of claim 31, wherein said crystal resonator is a
quartz crystal.
34. The system of claim 31, wherein the membrane-like region is
coated with metal electrodes on opposite sides thereof.
35. The system of claim 31, wherein the crystal resonators of
different sensor elements are modified with different reactive
molecules, thereby enabling detection of various foreign
materials.
36. The system of claim 31, wherein the control system is
configured and operable for actuating the crystal resonators,
measuring the change in the resonance frequency of the crystal
resonators, and generating measured data indicative of the identity
of said at least one foreign material.
37. The system of claim 1, configured for identifying one or more
foreign materials carried by a person, the system comprising a gate
having side and top walls defining the region of interest inside
the gate, said gate carrying on its side and top walls a plurality
of the sensor units such that the sensor units are exposed to air
medium of the region of interest.
38. The system of claim 37, wherein the gate is formed with air
outlets formed in the side and top walls thereof, the sensor unit
being mounted in the vicinity of the respective air outlets to be
thereby exposed to air medium of the region of interest.
39. A sensing system for use in identifying at least one foreign
substance in a region of interest, the sensing system comprising a
certain number of sensor units, the sensor unit comprising at least
one measurement unit comprising an array of at least two sensor
elements each configured and operable to be responsive to at least
one foreign substance in the vicinity thereof and to generate a
response signal indicative thereof, each sensor element being
mounted in its own separate compartment having an inlet and an
outlet thus defining an environmental region in the vicinity of the
sensor element separated from the surroundings of the compartment
and from at least one other compartment containing at least one
other sensor element.
40. A sensor unit for use in a sensing system for identifying at
least one foreign material in a region of interest, the sensor unit
comprising at least one measurement unit, the measurement unit
comprising one or more sensor elements each configured and operable
to be responsive to at least one foreign substance in the vicinity
thereof, each sensor element being mounted in its own compartment
having an inlet and an outlet thus defining an environmental region
in the vicinity of the sensor element separated from the
surroundings of the compartment.
41. A sensor unit for use in a sensing system for identifying at
least one foreign material in a liquid medium, the sensor unit
comprising: first and second measurement units, each comprising a
at least one sensor element, the sensor element being configured
and operable to be responsive to at least one foreign material in
its surroundings and generating a response signal indicative
thereof, a drive assembly associated with one of the first and
second measurement units for movement it into and out of the liquid
medium, a sample feeding unit configured and operable for providing
a flow of vapor from said liquid medium towards and through the
other measurement unit.
42. A gate unit having side and top walls defining a region inside
the gate, the gate comprising in the side and top walls one or more
air inlets for air blasting said region inside the gate and several
air outlets for sucking in an air sample from said region, and
comprising a plurality of sensor units mounted on the gate in the
vicinity of said air outlets, respectively, each sensor unit being
configured and operable to be responsive to at least one foreign
material in its surroundings and generating a response signal
indicative thereof.
43. A method for use in identifying at least one foreign material
in a region of interest, the method comprising: surrounding the
region of interest by a predetermined number of spaced-apart sensor
units, each sensor unit comprising at least one measurement unit
configured and operable to be responsive to at least to one foreign
substance in its surroundings and to generate a response signal
indicative thereof; providing a controllable air flow from region
of interest towards and through the measurement units.
Description
FIELD OF THE INVENTION
[0001] This invention is generally in the field of "electronic
nose" and "electronic tongue" devices, and relates to a method and
system for detection of various substances within a gas or liquid
medium or combination of such media.
BACKGROUND OF THE INVENTION
[0002] An "electronic nose" is known as a device formed by one or
more sensor and a pattern recognition routine. An "electronic
tongue" is a device similar to the electronic nose, but capable of
operating in a liquid medium, and enables the analysis of solutes
in a solution.
[0003] Various types of such devices have been developed and are
described for example in the following publications:
[0004] U.S. Pat. No. 6,167,747 discloses a vapor recovery system
that utilizes a crystal oscillator for sensing the presence of
hydrocarbon in the vapor emissions emanating from a fuel tank
during refueling. The crystal oscillator is coated with a layer of
material having sensitivity for hydrocarbon. In response to any
interaction between the coating layer and hydrocarbon, the crystal
oscillator experiences a shift in its oscillation frequency
relative to the fundamental resonance frequency. The frequency
shift is representative of the hydrocarbon concentration in the
vapor emissions. A control signal based on the frequency shift is
generated and then used to adjust the operating speed of the vapor
pump.
[0005] U.S. Patent Publication No. 2004/0069046A1 discloses a
portable vapor sensing device conveniently adapted for use in
sensing the presence and concentration of a wide variety of
specified vapors. The device provides these benefits using a sensor
module that incorporates a sample chamber and a plurality of
sensors located on a chip releasably carried within or adjacent to
the sample chamber. Optionally, the sensor module can be configured
to be releasably plugged into a receptacle formed in the device.
Vapors are directed to pass through the sample chamber, whereupon
the sensors provide a distinct combination of electrical signals in
response to each. The sensors of the sensor module can take the
form of chemically sensitive resistors having resistances that vary
according to the identity and concentration of an adjacent vapor.
These chemically sensitive resistors can each be connected in
series with a reference resistor, between a reference voltage and
ground, such that an analog signal is established for each
chemically sensitive resistor. The resulting analog signals are
supplied to an analog-to-digital converter, to produce
corresponding digital signals. These digital signals are
appropriately analyzed for vapor identification.
[0006] WO 04/057319 discloses a piezoelectric sensor arrangement
for analysis of fluid samples. The sensor arrangement includes a
signal source, a measuring device and a docking system, which
comprises a first part provided with means for receiving a sensor
element that exposes a piezoelectric quartz crystal and a second
part comprising fluid channels for the sample and a flow cell
element, which preferably is removable and which comprises a
recess, and inlet and outlet fluid channels for leading a fluid
through the recess. The first and second parts are movable in
relation to each other between a closed position and an open
position and are arranged such that in the closed position the
recess of the flow cell element is sealingly covered by the
piezoelectric quartz crystal so that a flow cell is formed by said
flow cell element and said quartz crystal.
[0007] U.S. Pat. No. 6,073,499 discloses a portal for use with a
detector for detecting trace amounts of contraband that may be
retained on skin or clothing of the human subject. The portal
relies upon the continuous process by which microscopic flakes of
skin continuously separate from human subjects. The portal further
relies upon the existence of a human thermal plume consisting of a
layer of warm air adjacent the all human subject. The warm air
rises in the cooler surrounding air and transports the microscopic
flakes of skin upwardly. The portal capitalizes on this phenomenon
by providing at least a partial enclosure with a funnel-shaped
collector above the human subject. A low speed flow of relatively
dense cool air may be introduced into the portal to buoyantly lift
the warmer air of the human thermal plume upwardly. The air stream
defined by the human thermal plume and the skin particles therein
moves to a trap in the funnel-shaped collector above the portal.
The trap cooperates with a detector for detecting the presence of
molecules of interest.
[0008] U.S. Pat. No. 6,831,273 discloses an apparatus for detecting
whether substances of interest are present in a sample of air. The
apparatus includes a detector, such as an ion trap mobility
spectrometer. The detector is operated at a high drift voltage and
then is switched to a low drift voltage. Spectra are collected at
the high and low field strengths and are compared with standard
spectra at those strengths to determine whether materials of
interest are present.
[0009] U.S. Pat. Nos. 6,708,572 and 6,840,122 disclose portal trace
detection systems for detection of imbedded minute particles of
interest, such as traces of narcotics, explosives and other
contraband. The apparatus includes a portal through which a human
suspect will pass. A detection apparatus is disposed at least
partly in the ceiling of the portal, and hence above the human
subject in the portal. Particles of interest will be entrained in
the human thermal plume that exists in the boundary layer of air
adjacent the suspect, and will flow upwardly from the suspect to
the detection apparatus in the ceiling of the portal. The portal
includes a plurality of vertically aligned arrays of air jets. The
air jets are fired sequentially from bottom to top to produce short
bursts of air sufficient to disturb the clothing of the suspect and
to dislodge particles of interest from the clothing. The dislodged
particles of interest are entrained in the air in the human thermal
plume and are transported upwardly to the detector.
[0010] U.S. Pat. No. 6,526,828, assigned to the assignee of the
present application, discloses sensitive and selective method and
device for the detection of trace amounts of a substance. The
device includes a piezoelectric crystal element comprising at least
one crystal resonator in the form of an inverted mesa structure,
which has a membrane-like region and is characterized by a certain
resonance frequency value. A surface region of the crystal
resonator is modified by reactive molecules of a kind capable of
interacting with the foreign material to yield a reaction product
that effects a change in the resonance frequency of the crystal
resonator from said certain resonance frequency value. This change
is indicative of the identity and quantity of the foreign
material.
SUMMARY OF THE INVENTION
[0011] There is a need in the art for a quick and effective
technique for identifying one or more analytes in a medium, such as
air vapor or liquid, providing a novel "electronic nose" or
"electronic tongue" method and system.
[0012] The present invention provides a sensing system for
identifying at least one foreign material in a region of interest.
The sensing system includes a predetermined number of sensor units.
The sensor unit comprises at least one measurement unit including
one or more sensor element (e.g., an array of sensor elements).
According to the invention, the sensor element is preferably
mounted in its own compartment thus separating the closest
environment of the sensor element from the surroundings. This
increases the concentration of a sample medium to be inspected when
supplied to the sensor element. When using at least two sensor
elements, each sensor element is mounted in its own compartment
separated from at least one other compartment containing at least
one other sensor element. The sensor element is configured and
operable to be responsive to at least one foreign material in its
surroundings and generating a response signal.
[0013] According to one broad aspect of the invention, there is
provided a sensing system for use in identifying at least one
foreign substance in a region of interest, the sensing system
comprising a certain number of sensor units, the sensor unit
comprising at least one measurement unit including one or more
sensor elements configured and operable to be responsive to at
least one foreign substance in the vicinity thereof and to generate
a response signal indicative thereof, the sensor element being
mounted in its own compartment having an inlet and an outlet thus
defining an environmental region in the vicinity of the sensor
element separated from the surroundings of the compartment.
[0014] According to another broad aspect of the invention, there is
provided a sensing system for use in identifying at least one
foreign substance in a region of interest, the sensing system
comprising a certain number of sensor units, the sensor unit
comprising at least one measurement unit comprising an array of at
least two sensor elements each configured and operable to be
responsive to at least one foreign substance in the vicinity
thereof and to generate a response signal indicative thereof, each
sensor element being mounted in its own separate compartment having
an inlet and an outlet thus defining an environmental region in the
vicinity of the sensor element separated from the surroundings of
the compartment and from at least one other compartment containing
at least one other sensor element.
[0015] The system may include more than one sensor unit, more
preferably several sensor units appropriately distributed around
the region of interest. The sensing system includes or is
associated with a control system. The latter is connectable to the
sensor unit(s) for receiving and analyzing the response signal(s)
and generating output signal indicative thereof.
[0016] The sensor elements containing compartments are arranged
within the measurement unit in a spaced-apart relationship. This
may for example be a circular array of sensor elements.
[0017] The sensing system also preferably includes a feeding unit
for providing an input flow of a sample medium from the region of
interest towards and through the measurement unit. Such a feeding
unit may or may not be a constructional part of the sensor unit. In
case of the circular array of the sensor elements' compartments,
the sample medium is concurrently supplied to all the compartments.
In case of a linear array, the sample medium is sequentially
supplied to all the compartments.
[0018] The sample feeding unit is preferably configured as one or
more suction assemblies. This may be one pump-like unit connected
to an outlet of the measurement unit; or also another pump-like
unit interconnected between the region of interest and an inlet of
the measurement unit. In the latter case, the two pump-like units
are operable in synchrony to provide a desired flow of the sample
medium through the measurement unit.
[0019] The sample feeding unit may include a separate sample
preparation unit connectable to the sensor unit; or an integrated
sample preparation unit connectable to the measurement unit. The
sample preparation unit may be configured as a separator for
separating and filtering out a purified gas medium and collecting
particles from the sample medium and directing a flow of the
collected particles to the measurement unit. The sample preparation
unit may include a pre-concentrate for collecting the sample
medium, and a heating unit for heating the sample medium.
[0020] The sensing system may include a heating unit. The heating
unit may be configured for heating the sample medium while flowing
towards the measurement unit; and/or for heating inner surfaces of
the sensor unit to prevent adsorption of the sample medium
thereon.
[0021] The sensor unit may be configured as a two-part assembly to
thereby enable operation of one sensor unit part during
regeneration of the other.
[0022] The sensing system of the present invention may be
configured for identifying one or more substances in a liquid
medium, preferably in addition to the inspection of vapors in the
vicinity of this liquid medium. To this end, the system includes a
lift-like assembly for moving the measurement unit into and out of
the liquid medium. The system may include two measurement units
configured such that the first measurement unit is located outside
the liquid medium during the system operation and is capable of
identifying one or more foreign substances in vapors in the
vicinity of the liquid medium, and the second measurement unit is
driven for movement into and out of the liquid medium.
[0023] The measurement unit is preferably configured such that the
compartments with the sensor elements are equally distanced from an
actuator utility of a control system. The compartments may be
arranged in a spaced-apart relationship along a circular path such
that the actuator utility is located on a central axis of the
circle, e.g., in the center of the compartments' plane.
[0024] Preferably, the sensor element is a piezoelectric crystal
resonator characterized by a certain resonance frequency value and
carrying reactive molecules of a kind capable of interacting with
at least one specific foreign material to yield a reaction product
that effects a change in the resonance frequency of the crystal
resonator. This change is indicative of the identity of the at
least one foreign material. The crystal resonator may be a quartz
crystal. The piezoelectric crystal resonator is preferably
configured as an inverted mesa structure having a membrane-like
region. The membrane-like region is coated with metal electrodes on
opposite sides thereof. Preferably, the crystal resonators of
different sensor elements are modified with different reactive
molecules, thereby enabling detection of various foreign materials.
The control system is configured and operable for actuating the
crystal resonators, measuring the change in the resonance frequency
of the crystal resonators, and generating measured data indicative
of the identity of foreign material(s).
[0025] The sensing system of the present invention may utilize a
gate having side and top walls defining the region of interest
inside the gate. Such a gate carries on its side and top walls a
plurality of the sensor units such that the sensor units are
exposed to air medium of the region of interest. Preferably, the
gate on its side and top walls is formed with one or more air
inlets for air blasting the region of interest and one or more air
outlets for sucking in the air sample from the region of interest.
The sensor units are mounted in the vicinity of the air outlets,
respectively.
[0026] According to yet another broad aspect of the invention,
there is provided a sensor unit for use in a sensing system for
identifying at least one foreign material in a region of interest,
the sensor unit comprising at least one measurement unit, the
measurement unit comprising one or more sensor elements each
configured and operable to be responsive to at least one foreign
substance in the vicinity thereof, each sensor element being
mounted in its own compartment having an inlet and an outlet thus
defining an environmental region in the vicinity of the sensor
element separated from the surroundings of the compartment.
[0027] According to yet another broad aspect of the invention,
there is provided a sensor unit for use in a sensing system for
identifying at least one foreign material in a liquid medium, the
sensor unit comprising: [0028] first and second measurement units,
each comprising at least one sensor element, the sensor element
being configured and operable to be responsive to at least one
foreign material in its surroundings and generating a response
signal indicative thereof, [0029] a drive assembly associated with
one of the first and second measurement units for movement it into
and out of the liquid medium, [0030] a sample feeding unit
configured and operable for providing a flow of vapor from said
liquid medium towards and through the other measurement unit.
[0031] According to yet another broad aspect of the invention,
there is provided a gate unit having side and top walls defining a
region inside the gate, the gate comprising in the side and top
walls one or more air inlets for air blasting said region inside
the gate and several air outlets for sucking in an air sample from
said region, and comprising a plurality of sensor units mounted on
the gate in the vicinity of said air outlets, respectively, each
sensor unit being configured and operable to be responsive to at
least one foreign material in its surroundings and generating a
response signal indicative thereof.
[0032] According to yet another broad aspect of the invention,
there is provided a method for use in identifying at least one
foreign material in a region of interest, the method comprising:
surrounding the region of interest by a predetermined number of
spaced-apart sensor units, each sensor unit comprising at least one
measurement unit configured and operable to be responsive to at
least one foreign substance in its surroundings and to generate a
response signal indicative thereof; providing a controllable air
flow from region of interest towards and through the measurement
units.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] In order to understand the invention and to see how it may
be carried out in practice, a preferred embodiment will now be
described, by way of non-limiting example only, with reference to
the accompanying drawings, in which:
[0034] FIG. 1 is a schematic illustration of a monitoring system of
the present invention used for detecting substances that might be
carried by a person;
[0035] FIG. 2A shows an example of the configuration of a sensor
unit of the present invention suitable to be used in system of FIG.
1;
[0036] FIG. 2B schematically illustrates another example of a
sensor unit of the present invention;
[0037] FIG. 3 shows an example of a measurement unit of the present
invention for use in the sensor unit;
[0038] FIG. 4 exemplifies a preferred configuration of a sensor
element suitable to be used in the measurement unit of the present
invention;
[0039] FIGS. 5 and 6 show two more examples, respectively, of a
sensor unit of the present invention;
[0040] FIG. 7 exemplifies another configuration of a sensor unit of
the present invention configured for inspecting liquid samples;
[0041] FIG. 8 exemplifies the configuration of a sensor element
suitable to be used in the sensor unit of FIG. 7;
[0042] FIGS. 9A-9C show the experimental results of using the
sensing unit of the present invention for identifying different
foreign substances;
[0043] FIGS. 10A and 10B illustrate the experimental results of
using the sensor unit of FIG. 7 for identifying acetic acid in a
liquid sample, where FIG. 10A shows data measured by the "gas
medium" measurement unit and FIG. 10B shows data measured by the
"liquid medium" measurement unit; and
[0044] FIGS. 11A and 11B illustrate the experimental results of
using the sensor unit of FIG. 7 for identifying urine vapor above
liquid level, using 150 MHz and 30 MHz measurement modes,
respectively.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0045] A sensor system of the present invention can be used for
detecting and analyzing various substances present in air vapor or
liquid medium. The technique of the present invention can be used
in a wide variety of commercial applications including, but not
limited to, detection of explosives or drugs, environmental
toxicology, biomedicine, such as microorganism classification or
detection, material quality control, food and agricultural product
monitoring, ambient air monitoring, employee protection, emissions
control, and product quality testing.
[0046] The technique of the present invention could be used for
substance detection in air vapor or liquid, thus acting as an
electronic nose and/or as an electronic tongue. A combined device
provides for simultaneous analysis of a solution and its vapors,
providing a complete picture of the detected material.
[0047] Reference is made to FIG. 1 exemplifying a monitoring system
10 of the present invention used for identifying substance(s) of
interest, for example explosives, that might be carried by a
person. The system 10 includes a sensing assembly 12 accommodated
in the vicinity of a person's path (constituting a region of
interest). In the present example, sensing assembly 12 includes a
plurality of chemical sensor units, three such sensor units 12A-12C
being shown in the present example, arranged in a spaced-apart
relationship around the person's path through a gate-like structure
14. The construction and operation of the sensor unit according to
the invention will be described further below.
[0048] Gate-like structure 14 typically defines a top side 14A and
side walls' assembly 14B around a region of interest (gate inside
region) 15. Sensor units 12A-12C are arranged at different
locations with respect to gate region 15, and accordingly with
respect to a person P in the gate region. As shown in the present
example, sensor unit 12A is associated with (i.e., is located on or
in the vicinity of) top side 14A of gate 14, and sensor units 12B
and 12C are associated with side walls' assembly 14B.
[0049] The inventors have found that the use of a plurality of
sensor units arranged at different locations with respect to a
region of interest (gate region in the present example)
significantly improves the effectiveness of detection and reduces
the time needed for effective detection. Preferably, each sensor
unit is an assembly of two-parts ("doubled unit"). This enables to
fasten the sensor unit preparation for the substance identification
process: when one unit undergoes regeneration, the other unit
performs substance identification.
[0050] As further shown in the figure, system 10 includes a sample
input arrangement 16 for providing a flow of a sample medium (e.g.,
air sample) from region of interest 15 into the sensor units. In
the present example, sample input arrangement 16 is associated with
an appropriate number of air outlets made in gate 14, three such
outlets 17 being shown in the present example associated with
sensors units 12A-12C respectively. Sample input arrangement 16 is
configured to suck an air sample 18 from gate region 15 into the
respective sensor unit via air outlet 17. It should be noted,
although not specifically shown, that the gate is also preferably
provided with one or more air inlets for air blasting the region
inside the gate.
[0051] Monitoring system 10 also includes a control system 20 which
is configured to analyze data indicative of the measurement results
coming from an appropriate utility of the sensor unit (as will be
described below) and generate an output warning signal. The control
system 20 is typically a computer system including inter alia a
data input utility 20A, a memory utility 20B, a data processing and
analyzing utility 20C, and a data output utility (e.g., display)
20D.
[0052] In the present example, control system 20 is shown as a
stand alone system connectable (via wires or wireless) to the
output of sensor units 12A-12C. It should, however, be understood
that the present invention is not limited to this specific example,
and alternatively, the control system may be formed by control
units integrated within the respective sensor units. Output data of
a specific sensor unit indicative of the existence of substance(s)
of interest might be sufficient to identify the condition of the
gate region (region of interest) as including the substance(s) of
interest. The output warning signal may be a light or acoustic
signal.
[0053] Reference is made to FIG. 2A, schematically illustrating an
example of a sensor unit 112 of the present invention suitable to
be used in a monitoring system 10 (FIG. 1). Sensor unit 112
includes a measurement unit 30 including one or more sensor
elements. According to the invention, each sensor element is
preferably mounted in its own compartment having air flow inlet and
output, and defines the environmental region in the vicinity of the
sensor element separated from the surroundings of the compartment.
Thus, in case an array of sensors is used, each sensor is in its
own compartment, separated from other compartment(s) containing
other sensor element(s) respectively, as will be described further
below with reference to FIG. 3. The sensor element is configured
and operable to be responsive to at least one foreign material in
its surroundings and generate a response signal indicative
thereof.
[0054] Preferably, sensor unit 112 also includes a heating unit 38
(one or more heater elements) configured for heating the sample
prior to entering measurement unit 30. In the present example,
sample S is heated while flowing towards measurement unit 30. To
this end, sensor unit 112 defines a transport path 40 to wards the
measurement unit, and the heating unit is associated with this
path, e.g., extends along this path. This may be implemented by
providing a tube 40 (e.g., of about 5 mm diameter) along which a
direct continuous flow of an air-vapor sample S is provided from
outside towards measurement unit 30. Two spaced-part heater
elements 38 (or spaced-apart arrays of heater elements) are
accommodated at opposite sides of tube 40. Tube 40 is connected to
an inlet 30A of measurement unit.
[0055] It should be noted, although not shown here, that preferably
the sample is previously prepared (e.g., by separation of particles
from air and heating the sample, as will be exemplified further
below) in a separate sample preparation unit.
[0056] Further provided in sensor unit 112 is a suction unit 36
accommodated adjacent to measurement unit 30 and connected thereto
through an appropriate tube-like connector 35. Unit 36 is a
pump-like assembly having a chamber 36A with an inlet 36B
connectable to tube 35 and thus to measurement unit 30, an outlet
36C, and a piston 36D. The latter is operable by a control unit 37
to provide a desired flow of sample S through measurement unit 30.
Thus, section unit 36 serves for passing the sample flow through
measurement unit 30. Suction unit 36 may also serve for feeding
clean air or inert gas into measurement unit 30 for cleaning the
system and preparing it for further measurements.
[0057] It should be noted that an appropriate number of sensor
units (or doubled units as the case may be) varies with the device
application. For example, for the application exemplified in FIG.
1, namely for detection and identification of explosives that might
be carried by a passenger (e.g., in airport), seven sensor units
might be used, three sensor units at each side wall and one sensor
unit at the top wall of the gate. Preferably, each unit is a
two-part unit, as described above, thus the total number of sensor
units associated with the gate being 14.
[0058] The technique of the present invention provides for a very
short detection time. The detection time, including time required
for suction of an air sample and its preparation for feeding to
sensors containing compartments (described further below), for the
chemical analysis, and for the data processing and outputting the
results, can practically be of about 12 seconds or less, where the
time period for the chemical analysis, data processing and
outputting the results is about 1-2 seconds.
[0059] Referring to FIG. 2B, there is schematically illustrated
another example of a sensor unit 212 of the present invention. In
the present example of FIG. 2B, sensor unit 212 is configured for
inspecting an air-vapor sample.
[0060] It should be noted that a sensor unit of the present
invention may also be configured for detecting foreign substance(s)
in a liquid medium, which will be exemplified further below with
reference to FIG. 7.
[0061] Sensor unit 212 includes a measurement unit 30 and a sample
feeding unit 32 for passing the sample flow through the measurement
unit. Measurement unit 30 is configured as described above namely
includes sensor elements each mounted in its own compartment
separated from other compartment(s) containing other sensor
element(s) respectively.
[0062] Sample feeding unit 32 includes an input unit 34 and an
output unit 36 at opposite sides of measurement unit 30. Input unit
34 is either connectable to an external sample input arrangement in
the vicinity of a region of interest, or as shown in the present
example is configured as the sample input arrangement for providing
a flow of a sample medium towards measurement unit 30.
[0063] Input unit 34 presents a pump-like assembly having a chamber
34A with an inlet 34B exposed to the region of interest, an outlet
34C, and a movable piston 34D driven by a control unit 37. It
should be understood that control unit 37 may or may not be part of
the control system (10 in FIG. 1) associated with the sensor output
signals. Output unit 36 is a similar pump-like assembly having a
chamber 36A with an inlet 36B connectable via an appropriate
tube-like connector 35 to measurement unit 30, an outlet 36C, and a
piston 36D. Piston 36D is operable by control unit 37 synchrony
with piston 34D, to provide a desired flow of a sample S through
measurement unit 30. Pistons 34D and 36D operate in opposite
operational modes: when piston 34D presses the sample out of
chamber 34A towards measurement unit 30, piston 36D sucks this
sample into measurement unit 30. Output unit 36 may also serve for
feeding clean air or inert gas into measurement unit 30 for
cleaning the system and preparing it for further measurements.
[0064] Preferably, sensor unit 212 also includes a heating unit 38,
which in the present example is configured and accommodated similar
to the above-described example of FIG. 2A, namely associated with
the sample flow path from the input unit towards the measurement
unit. It should be noted, although not specifically shown here,
that heating unit 38 may include additional heating element(s)
associated with input unit 34, namely accommodated for heating the
air sample while in the input unit.
[0065] Thus, inlet 34A of input unit 34 is connectable to the
region of interest (e.g., to air outlet 17 in gate 14 in FIG. 1),
and outlet 34B is connectable to the sample transport path 40 (or
directly to measurement unit 30 as the case may be).
[0066] For example, the sample is heated to 140-200.degree. C. The
heating temperature is defined by the evaporation temperature of
foreign material(s) to be detected. The vapor flow towards and
through the measurement unit is defined by the operation of input
and output pump-like assemblies 34 and 36. For example, the air
vapor flow of 0.5 m/sec rate through the sensor element compartment
provides the sensor element response time of about 1 sec.
[0067] Reference is made to FIG. 3 illustrating an example of a
measurement unit 130 according to the invention suitable to be used
in the sensor unit. Measurement unit 130 includes an array of
sensor elements (piezoelectric crystal resonators), eight such
elements 50-57 being shown in the present example arranged in a
circular array with equal spacings between the elements. Sensor
elements 50-57 are mounted in compartments 60-67, respectively.
Compartments with sensor elements are mounted on a measurement
matrix 74. The latter is configured as a chamber appropriately
shaped (e.g., cylinder) to ensure substantially uniform
distribution of evaporated and transported sample among all the
sensor elements. Matrix 74 is mounted on a support structure 76
presenting a cavity into which the compartments can be opened.
[0068] Each compartment has an inlet opening, generally at 70, and
an outlet opening, generally at 72, for the sample flow through the
compartment. During the system operation, the sample enters the
compartment through inlet 70 and emerges therefrom through outlet
72. During the system regeneration, these inlet and output openings
serve for the flow of a clean gas (air or inert agent) through the
compartment. The dimensions and shape of the compartment, as well
as those of inlet and outlet openings and the cavity 76, are
selected so as to meet the aerodynamic requirements, consisting of
providing natural oscillations of piezo-sensors on the one hand,
and a desired speed of the sample free flow on the other hand.
[0069] Thus, each sensor element is accommodated in its own
compartment separated from those of other sensor elements. The air
flow carrying the sample to be inspected is equal for all the
sensors. The amount, speed and pressure of this flow are
controlled. In this case, unavoidable noise is reduced to minimal
(a few tens of Hertz at the crystal vibration frequency of 250
MHz). Such a configuration of the measurement unit provides for a
significant increase in the possibility of substance detection,
increase in adsorption processes, which leads to a practically
immediate substance identification (in about 1 second).
[0070] In order to provide homogeneous flow of the sample towards
all the sensor elements, the sensor elements may be arranged in a
linear array such that the sample is sequentially supplied to the
sensor elements (e.g., the 60 mm length chamber of the measurement
unit including an array of 8 sensor elements), or may be arranged
in a circular array as shown in FIG. 3 in which case the sample is
concurrently supplied to all the sensors.
[0071] Preferably, the piezoelectric crystal resonator is
configured as an inverted mesa structure having a membrane-like
region and being characterized by a certain resonance frequency
value (e.g., 0.1-1.2 GHz), the crystal resonator being excitable by
the environment to cause a change in the resonance frequency
thereof from this certain resonance frequency value. This technique
is described in U.S. Pat. No. 6,526,828, assigned to the assignee
of the present application.
[0072] This is illustrated in FIG. 4, showing sensing element 50,
which is a quartz crystal resonators in the form of an inverted
mesa structure defining a membrane-like region 50A having a
thickness of about several micrometers, between thicker end regions
50B of the crystal. To fabricate such an inverted mesa structure, a
crystal is patterned either at one side thereof to form one recess,
or at both opposite sides thereof (as shown in the present example)
to form two opposite recesses, thereby forming membrane central
region 50A of a sufficiently small thickness (to obtain desirably
high sensitivity of the sensor). Metal electrodes 81A and 81B (made
from Al, Pt or Au) are deposited onto opposite surfaces of
membrane-like region 50A. Quartz crystal resonator 50 is formed
with a surface region 82 (exposed to the environment) modified by
reacting molecules intended to interact with one or more specific
foreign materials that may be present in the environment. In the
present example, this is implemented by coating electrodes 81A and
81B with such a molecule. Generally, such a modified surface region
may include the surface of the electrodes (or only one electrode
located on that side of the device by which it is exposed to
environment), the surface of the membrane-like region, or both. An
interaction between these molecules and one or more specific
foreign material affects the frequency of vibration of the crystal
resonator to change it from the certain resonance frequency value.
This change is detected by the corresponding utility of the control
system. The principle of the detection is that the frequency of
vibration of an oscillating crystal is decreased by the absorption
of a foreign material on its surface. A foreign material is
selectively absorbed by the coating (on the crystal surface or/and
on the metal electrode surface coating the crystal surface),
thereby increasing the weight of the crystal and decreasing the
frequency of vibration.
[0073] What is actually detected by the sensor unit utilizing
several crystal resonators is the so-called "electronic image" or
pattern of the intensities of response of each of the crystal
resonators. These responses are indicative of diminution of the
vibrating frequencies of the crystal resonators caused by the
absorption of foreign materials.
[0074] The modification of the surface region of the crystal
resonator may be achieved by two alternative techniques: (1)
construction of organized, self assembled monolayers (SAM); or (2)
formation of polymeric layer. SAM consists of receptor compounds
comprising a linker that connects this compound to the surface of a
substrate, an optional spacer, a structural element and an active
head group. Relating to the formation of a polymeric layer, the
preferred technology for forming a polymer layer in a controlled
manner is by electropolymerization.
[0075] FIG. 5 illustrates yet another example of a sensor unit 312
of the present invention for inspecting an air-vapor medium sample
for foreign substance(s). Sensor unit 312 is configured as a
portable table-type device. To facilitate understanding, the same
reference numbers are used for identifying components that are
common in all the examples of the invention.
[0076] Sensor unit 312 includes a measurement unit 30 and a suction
assembly 32. Measurement unit 30 is configured generally as
described above, and namely includes an array (e.g., circular
array) of crystal resonators, each in its own compartment separated
from other sensor element(s), preferably with the resonator
configuration as a mesa structure. Suction assembly 32 includes an
input unit 234 having a pump-like assembly formed by a chamber 34A
with inlet 34B and outlet 34C and a driven piston 34D, and an
output unit 36 configured as a similar pump-like assembly formed by
a chamber 36A with inlet 36B and outlet 36C and a driven piston
36D. Input and output pump-like assemblies (their pistons 34D and
36D) are synchrony operated as described above to provide a desired
flow of a sample medium S through measurement unit 30.
[0077] In the present example of FIG. 5, input assembly 234 also
includes a sample preparation unit 42 configured for accommodating
a pre-concentrate 44. The latter is configured as a mesh of an
array of small cells, for example made of stainless steel, kept
under tension between two metal rings (a tambour-like assembly).
Such a pre-concentrate assembly 44 is appropriately insertable into
chamber 42. Further provided in sensor unit 312 is an additional
heating unit 46, which in the present example is in the form of two
spaced-apart heaters (or two arrays of heaters) 46A and 46B at
opposite sides of chamber 34A so as to be at opposite sides of the
sample flow from chamber 34A towards a sample flow path 40 and also
optionally an internal heater 46C inside chamber 34A. Sample S is
thus appropriately heated, and a resulting vapor flows towards
measurement unit 30.
[0078] Thus, the sample may be supplied into the measurement unit
in one of the following ways: using heating a special
pre-concentrate, which provides evaporation and flow of vapor of
the material collected on the pre-concentrate; by depositing a
certain amount of a sample material onto the pre-concentrate with
no heating; or by direct suction of a sample media and flowing it
to and through the measurement unit. To prevent adsorption of the
sample media on the inner walls of the input chamber as well as on
the piston of the input unit, these walls and piston as well as
other inner surfaces of the input unit, where collection and
momentary storage of the sample might occur, could be heated up to
a temperature sufficient to avoid the adsorption. Similarly, all
the system parts through which the sample media is supplied to the
measurement unit, could be appropriately heated. The use of
additional internal heater 46C (e.g., IR laser) provides for
accelerating the entire detection process.
[0079] FIG. 6 shows yet another example of a sensor unit 412 of the
present invention. Sensor unit 412 includes a measurement unit 30
and a suction assembly 32. Measurement unit 30 is preferably
configured as described above, namely includes an array (e.g.,
circular array) of crystal resonators (preferably in the form of
mesa structures), each in its own compartment separated from other
sensor element(s). Suction assembly 32 includes an input unit 334
and an output unit 36 at opposite sides of measurement unit 30.
Preferably, sensor unit 412 also includes a heating unit 38
associated with a sample flow path 40 from input unit 334 to
measurement unit 30.
[0080] In the present example, input unit 334 is a separate unit
connectable to an inlet of measurement unit 30 or to inlet of path
40, and is configured as a separator assembly formed by a single
separator or an array of separators arranged in a cascade-like
manner. Such a separator may for example include a cyclone-like
assembly configured for the purposes of the present invention for
filtering out, via outlet 34E, a part of the sample purified from
dust and other particles, while collecting the remaining part
(particles) of the sample and directing it into measurement unit 30
via outlet 34C. The collected part of the sample medium is
preferably heated (e.g., to 140-200.degree. C.) by heating unit 38
prior to entering measurement unit.
[0081] The system of the present invention operates as follows: A
sample of media from a region of interest is input into the sensor
unit. The sample may be directly flowed from the region of interest
to and through the measurement unit (a matrix carrying a plurality
of sensors) as exemplified in FIGS. 2A-2B and 6, or may be first
collected and prepared (using a pre-concentrate with or without
heating) and then flowed to the measurement unit as exemplified in
FIG. 5.
[0082] As indicated above, the sensor unit of the present invention
may be configured for detecting foreign substance(s) in a liquid
medium as well. This is illustrated in FIG. 7. A sensor unit 512 is
configured as a portable table-type device, and is formed by two
concurrently operating parts 512A and 512B both associated with a
reservoir 90 containing a liquid to be inspected. One part 512A of
the sensor unit is configured for inspecting an air-vapor sample
for one or more foreign substances, and includes a first
measurement unit 30 (to be located outside the liquid medium during
the device operation) and a suction unit 36, and preferably also
includes a heating unit 38, for example in the form of an
annular-shape element (all configured and operable as described
above with reference to FIG. 2A). The other part 512B of the sensor
unit is configured and operable to examine a liquid sample, and
includes a second measurement unit 30' which is configured similar
to the first measurement unit 30 and is driven to be dipped into
the liquid at a predetermined depth during the device operation.
The second measurement unit is associated with a regeneration unit
92 such that when this measurement unit is moved out of the liquid
medium, the sensor elements' matrix undergoes regeneration. Each
sensor element of unit 30' is to be completely dipped into the
liquid. In order to smoothly dip the sensors into liquid at a
predetermined depth, a micro-lift assembly 92 is provided being
appropriately operated by a control unit 37. Preferably, an
additional heater 38C is provided for heating the liquid in
reservoir 90. Each of the measurement units 30 and 30' includes a
single sensor element, preferably mounted in a compartment; or an
array of two or more sensor element, for example arranged as
described above (i.e., each in its own compartment).
[0083] FIG. 8 exemplifies the configuration of a sensor element 50
of measurement unit 30'. As shown, the sensor element is configured
such that, when being dipped into liquid, only one side thereof is
exposed to liquid while the other side is sealed.
[0084] To actuate oscillations of the crystal resonators (sensor
elements) of measurement units 30 and 30', appropriate electric
signals are applied. With regard to measurement unit 30', the power
supply should be such as to ensure that the crystal resonator's
oscillations could overcome the oscillations of liquid medium.
Electrical signals providing activation of the crystal resonators
are created by a specifically design electron circuit operating as
the so-called "electronic oscillator" or "amplifier". The
construction and operation of such an electronic circuit do not
form part of the present invention and therefore need not be
specifically described. For example, a symmetric electronic
circuit, disclosed in the above-indicated U.S. Pat. No. 6,526,828
assigned to the assignee of the present application, can be used.
Sensors used in the air-medium related measurement unit may for
example operate with about 250 MHz frequency of oscillations, as
described in U.S. Pat. No. 6,526,828. The liquid-medium related
measurement unit may operate with about 30 MHz frequency.
[0085] When sensor element(s) of unit 30' is/are dipped into
liquid, the sensor element(s), coated with appropriate
adsorbent(s), can adsorb specific substance(s) present in the
liquid. In this case, the frequency of oscillation of the sensor
element(s) is changed in accordance with concentration of the
specific substance(s), and in case of a plurality of such elements
in accordance with the selectivity of the coating on the sensor
elements. When the adsorbed substances are analyzed, measurement
unit 30' is lifted up, and the matrix of sensor elements is dried
(flowed by clean and warm air). Thus, sensor unit provides for
concurrently analyzing vapors and substances in a liquid
medium.
[0086] The following are experimental results for the technique of
the present invention.
[0087] Reference is made to FIGS. 9A-9C showing the experimental
results of using the sensor unit of the present invention for
identifying various foreign substances in an air sample, namely TNT
(explosives), Toluene and Methanol (volatile substances). In the
present example a sensor unit formed by a circular array of eight
sensor elements was used (each sensor element in its own separate
compartment). As shown for example, for TNT (FIG. 9A), a time
period of 2 seconds is sufficient for the detection of a certain
substance, while in the 1.5-2 sec time period the order of the
sensor elements order is determined in accordance with the
adsorption level defined by a selective coating on the sensor
element surface. This is more clearly illustrated in the spectral
graph. The amplitude of response of each sensor element, relative
to the other sensor elements presents a stable sequence, which is
weakly dependent on the amount of substance and the temperature
conditions. This sensors' sequence, termed "finger print" or
"image" of the substance, showed the repetition close to 10%.
[0088] FIGS. 10A and 10B illustrate the experimental results of
using the sensor unit of the present invention for identifying
acetic acid in a liquid sample. FIG. 10A shows data measured by the
"gas medium" measurement unit (30 in FIG. 7). This measured data is
in the form of time variations of the crystal resonators'
oscillations (eight resonators in the present example) and the
spectral representation of the same. FIG. 10B shows data measured
by the "liquid medium" measurement unit (30' in FIG. 7). In the
present example, measurement unit 30 was built from a circular
array of sensor elements and unit 30' from a single sensor element,
but is should be understood that the present invention is not
limited to this specific example.
[0089] FIGS. 11A and 11B illustrate the experimental results of
using the sensor unit of the present invention for identifying
urine vapor above liquid level. FIG. 11A shows data measured by the
150 MHz measurement unit 30 (FIG. 7). FIG. 11B shows data measured
by the 30 MHz measurement unit 30. In the present example,
measurement unit 30' was built from a circular array of sensor
elements, but is should be understood that the present invention is
not limited to this specific example.
[0090] Thus, the present invention provides a simple and effective
monitoring system for detecting various foreign materials in the
vicinity of a sensor unit. Accommodation of the sensor element in a
separate compartment significantly improves the substance
identification and makes it very quick. The use of a suction
assembly provides for controlling the speed, temperature and
pressure of the sample flow to and through the measurement unit.
The separation between the measurement unit and the sample
preparation unit (as exemplified in FIG. 5) allows for eliminating
or at least significantly reducing the affect of the sensor element
accommodation in space (in the gravity field) on the
sample-carrying flow in the measurement unit.
[0091] Those skilled in the art will readily appreciate that
various modifications and changes can be applied to the embodiments
of the invention hereinbefore exemplified without departing from
its scope defined in and by the appended claims.
* * * * *