U.S. patent application number 11/221565 was filed with the patent office on 2007-03-15 for sensor based mattress/seat for monitoring pressure, temperature and sweat concentration to prevent pressure ulcerations.
Invention is credited to Bakul Dave, Sumeer Lal, Ajay Mahajan, Jayant Nath.
Application Number | 20070056101 11/221565 |
Document ID | / |
Family ID | 37853546 |
Filed Date | 2007-03-15 |
United States Patent
Application |
20070056101 |
Kind Code |
A1 |
Mahajan; Ajay ; et
al. |
March 15, 2007 |
Sensor based mattress/seat for monitoring pressure, temperature and
sweat concentration to prevent pressure ulcerations
Abstract
A system for detecting conditions to prevent a bedsore includes
a first sensor to detect a first condition that results in the
bedsore and to output a first sensor signal from the first sensor
indicative of the first condition that results in the bedsore, a
controller to receive the first sensor signal and to determine if
the condition may result in the bedsore and an alarm responsive to
the controller to provide an alarm to indicate that the condition
may result in the bedsore.
Inventors: |
Mahajan; Ajay; (Murphysboro,
IL) ; Lal; Sumeer; (Greenwood, SC) ; Nath;
Jayant; (Overland Park, KS) ; Dave; Bakul;
(Carbondale, IL) |
Correspondence
Address: |
Wilson Daniel Swayze, Jr
3804 Clearwater Ct.
Plano
TX
75025
US
|
Family ID: |
37853546 |
Appl. No.: |
11/221565 |
Filed: |
September 8, 2005 |
Current U.S.
Class: |
5/600 |
Current CPC
Class: |
A61G 2203/46 20130101;
A61G 7/057 20130101; A61G 2203/34 20130101 |
Class at
Publication: |
005/600 |
International
Class: |
A47B 71/00 20060101
A47B071/00 |
Claims
1) A system for detecting conditions to prevent a bedsore,
comprising: a first sensor to detect a first condition that results
in said bedsore and to output a first sensor signal from said first
sensor indicative of said first condition that results in said
bedsore; a controller to receive said first sensor signal and to
determine if said condition may result in said bedsore; and an
alarm responsive to said controller to provide an alarm to indicate
that said condition may result in said bedsore.
2) A system for detecting conditions to prevent a bedsore as in
claim 1, wherein said first sensor includes a chlorine sensor to
detect the presence or absence of chlorine.
3) A system for detecting conditions to prevent a bedsore as in
claim 1, wherein said system includes a second sensor to detect a
second condition that results in said bedsore and to output a
second sensor signal from said second sensor indicative of said
second condition that results in said bedsore
4) A system for detecting conditions to prevent a bedsore as in
claim 3, wherein said system includes a third sensor to detect a
third condition that results in said bedsore and to output a third
sensor signal from said third sensor indicative of said third
condition that results in said bedsore.
5) A system for detecting conditions to prevent a bedsore as in
claim 3, wherein said second sensor includes a pressure sensor to
detect pressure.
6) A system for detecting conditions to prevent a bedsore as in
claim 4, wherein said third sensor includes a temperature sensor to
detect temperature.
7) A system for detecting conditions to prevent a bedsore as in
claim 2, wherein said chlorine sensor includes a chlorine sol-gel
sensor.
8) A system for detecting conditions to prevent a bedsore as in
claim 5, wherein said pressure sensor includes a pressure sol-gel
sensor.
9) A system for detecting conditions to prevent a bedsore as in
claim 5, wherein said pressure sensor includes a pressure liquid
crystal sensor.
10) A system for detecting conditions to prevent a bedsore as in
claim 6, wherein said temperature sensor includes a temperature
liquid crystal sensor.
11) A method for detecting conditions to prevent a bedsore,
comprising the steps of: sensing to detect a first condition that
results in said bedsore and to output a first sensor signal
indicative of said first condition that results in said bedsore;
receiving said first sensor signal and determining if said
condition may result in said bedsore; and sending an alarm to
indicate that said condition may result in said bedsore.
12) A method for detecting conditions to prevent a bedsore as in
claim 11, wherein said sensing said first condition includes
sensing to detect the presence or absence of chlorine.
13) A method for detecting conditions to prevent a bedsore as in
claim 11, wherein said method includes sensing to detect a second
condition that results in said bedsore and to output a second
sensor signal indicative of said second condition that results in
said bedsore
14) A method for detecting conditions to prevent a bedsore as in
claim 13, wherein said method includes sensing to detect a third
condition that results in said bedsore and to output a third sensor
signal indicative of said third condition that results in said
bedsore.
15) A method for detecting conditions to prevent a bedsore as in
claim 13, wherein said sensing said second condition includes using
a pressure sensor to detect pressure.
16) A method for detecting conditions to prevent a bedsore as in
claim 14, wherein said sensing said third condition includes using
a temperature sensor to detect temperature.
17) A method for detecting conditions to prevent a bedsore as in
claim 12, wherein said sensing said first condition includes using
a chlorine sol-gel sensor.
18) A method for detecting conditions to prevent a bedsore as in
claim 15, wherein said sensing said second condition includes using
a pressure sol-gel sensor.
19) A method for detecting conditions to prevent a bedsore as in
claim 15, wherein said sensing said second condition includes using
a pressure liquid crystal sensor.
20) A method for detecting conditions to prevent a bedsore as in
claim 16, wherein said sensing said third condition includes using
a temperature liquid crystal sensor.
Description
FIELD OF THE INVENTION
[0001] The present invention is in the field of biotechnology and
relates to a method and apparatus for preventing pressure
ulcerations, and more particularly, the present invention relates
to a sensor system for mattress/seats and other devices which a
human may come in contact with to measure pressure, temperature and
sweat concentrations to prevent pressure ulcerations.
BACKGROUND
[0002] The development of sol-gel techniques for processing
optical-quality thin films of silica glass has been established for
various applications. One of the interesting features of the
sol-gel application is that it enables one to synthesize inorganic
glasses at room temperature without melting. One consideration is
that the low temperature sol-gel approach circumvents the inability
of the molecules to withstand the high temperatures required in the
processing of oxides.
[0003] Patient immobility and debilitation are a significant health
concern in the world today. This is of significant concern to
patients who are suffering from a long-term illness such as trauma
victims and spinal cord injury patients and who benefit from a
health-care system that in some cases has lengthened and improved
the quality of life. However, these patients may not able to move
themselves, and consequently, these patients must rely on others
for movement. A significant problem that results from this lack of
mobility and that plagues these patients and consequently affects
the staff of nursing homes and skilled nursing facilities is
decubitus ulcers and bedsores. This complication has resulted in
the death of one of the most well-known spinal cord injured
patients, namely Christopher Reeve. Around-the-clock staffing for
the health of the patient is available for only a minority of
patients. Most patients will only have the services of a staff
member for only short periods of time during the day. Because of
the large and ever increasing number of patients assigned to an
individual staff member, monitoring of all the needs for these
patients is quite challenging. During these short periods of time
that is available to each patient, the staff member may overlook
the need to move these immobile patients, and the result may be
decubitus ulcers or bed sores.
[0004] Each year, approximately 2,000,000 bedridden patients
develop bedsores or pressure ulcers at an estimated cost of
approximately $9 billion in medical expenses to treat these
disorders. If vascular and diabetic ulcers are included, the cost
can rise by approximately 5 times this amount. This figure does not
take into account the number of days of lost productivity from the
people suffering these wounds. A significant number of bed sore
problems also occur in nursing homes and homes with patients
confined to wheelchairs. There are approximately 1.6 million
elderly and disabled people in over 17,000 nursing homes in this
country alone. Of these nursing home residents, a significant
percentage, approximately 13% develop bedsores every year. In 1995,
the Department of Health and Human Services issued the toughest
nursing home regulations in the history of the Medicare and
Medicaid programs and which has led to measurable improvements in
the quantity of care but have not completely eliminated the problem
of bedsores. Today, there is no automatic system for monitoring
pressures in bedridden and wheelchair confined patients.
Consequently, patients are turned in their beds systematically and
periodically to prevent bedsores.
References
[0005] 1.
http://www.virginia.edu/topnews/textonlyarchive/September.sub.--1995/W
HITAKER.txt, Jul. 12, 2002. [0006] 2.
http://www.aradvocate.com/HCFA_initiatives.html, Jul. 12, 2002.
[0007] 3. Taylor and Bader, "Sweat analysis following pressure
ischaemia in a group of debilitated subjects," J Rehab Res Dev.,
1997 July;34(3):303-8. [0008] 4. Taylor and Bader, "The analysis of
metabolites in human sweat: analytical methods and potential
application to investigation of pressure ischaemia of soft
tissues," Ann Clin Biochem, 1994 Jan;31 (Pt 1): 18-24. [0009] 5.
Sprigle, Linden, McKenna, Davis and Riordon, "Clinical skin
temperature measurement to predict incipient pressure ulcers," Adv
Skin Wound Care, 2001 May-Jun; 14(3):133-7. [0010] 6. Hickerson,
Slugocki, Thaker, Duncan, Bishop and Parks, "Comparison of total
body tissue interface pressure of specialized pressure relieving
mattresses," J. Long term Eff Med Implants, 2004; 14(2);81-94.
[0011] 7. Hamanami, Tokuhira and Inoue, "Finding the optimal
setting of inflated air pressure for a multicell air cushion for
wheelchair patients with spinal cord injury, " Acta Med Okyama,
2004 Feb; 58(1);37-44.
SUMMARY
[0012] A class of environmentally-responsive glasses has been
designed to respond to different environmental stimuli. These
glasses are prepared by the low temperature, solution based,
sol-gel process by using organically-modified
bis-[3-(trimethoxysilyl) propyl] ethylendiamine(enTMOS) precursor.
Starting from the molecular precursor, the sol-gel reaction yields
a solid state glass and a mechanically robust yet elastic material
that is capable of generating dynamic responses when subjected to
different physicochemical stimuli. These sol-gel glasses exhibit
bulk changes in volume and respond to the application of different
physicochemical chemical stimuli with the swelling/de-swelling
being reversible, consistent and reproducible. The sol-gel
undergoes a substantial change in volume when exposed to different
stimuli. The change in volume is a result of the amount of liquid
that is absorbed or expelled by the sol-gel. Consequently, the
amount of liquid affects the electrical properties of the sol-gel.
The larger the volume and correspondingly the larger amount of
liquid reduce the electrical resistance of the sol-gel, increasing
current. Incorporating the sol-gel into a sensor results not only
in the ability to determine the presence of the stimuli but to
provide a quantitative determination of the amount of stimuli
present. The chemical interaction of these sol-gels with different
molecules based on the charge, size and
hydrophobicity/hydrophilicity can be exploited for separation of
these molecules from a mixture. Typically, when the sol-gels are
placed in a solution containing a mixture of different molecules,
the sol-gels intake preferred species while leaving others out.
This feature can be effectively used for the separation of species
based on chemical structure of different molecules.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 illustrates the sensor system of the present
invention;
[0014] FIG. 2 illustrates the signal conditioning and data transfer
unit;
[0015] FIG. 3 illustrates a central monitoring station;
[0016] FIG. 4 illustrates a chlorine sensor;
[0017] FIG. 5 illustrates a graph of the chlorine sensor;
[0018] FIG. 6 illustrates a pressure sensor:
[0019] FIG. 7 illustrates a graph of the pressure sensor.
[0020] FIG. 8 illustrates a flow chart to form the chlorine
sensor;
[0021] FIG. 9 illustrates a flow chart to form electrodes;
[0022] FIG. 10 illustrates a flow chart to form the pressure
sensor.
DETAILED DESCRIPTION
[0023] FIG. 1 illustrates the sensor system 100 for obtaining
information from a patient and evaluating that information to
determine if a bed sore is developing on the patient. Bed sores
include pressure ulcerations, vascular and diabetic ulcers. The
sensor system 100 includes a suite of sensors, for example FIG. 1
shows three types of sensors 109, 108, 110 which may be a chlorine
sensor 108 to detect chlorine ions that are emitted from the
patient, a temperature sensor 109 to detect the temperature of the
patient at a location and a pressure sensor 110 to detect the
pressure of the patient against a surface in order to make a
determination if conditions are favorable for the development of
bed sores. Chlorine, excessive pressure and temperature have been
found to contribute to the development of bedsores. The specific
contributions to development of bed sores of chlorine, pressure and
temperature vary from patient to patient. The chlorine sensor 108
and the pressure sensor 110 may be constructed from sol-gel or from
any other suitable sensor material in order to obtain information
to determine if conditions are favorable for the development of bed
sores. The temperature sensor 109 and the pressure sensor 110 may
be constructed from liquid crystals which is an organic compound
having properties that appear to be both fluid and crystalline
simultaneously or may be constructed from any other suitable
material. These liquid crystals behave in accordance with distinct
optical properties that change when subjected to changing pressure
and temperature. The color changing ability of the liquid crystals
results in these liquid crystals being suitable for use for the
pressure and temperature sensors 109,110. For example, liquid
crystal can change in the visible color spectrum with a temperature
change of 2.degree. C. The temperature change can be expanded, and
the starting point of the range can be changed. Conversely, the
liquid crystals can be made to hold a particular color over a wide
range of temperatures for example 10 to 60.degree. C. Transparent
liquid crystal sheets could be formed to provide the pressure and
temperature sensors. Liquid crystal paint could be coated on a
substrate including plastic, glass or metallic surfaces, and the
resulting sheet would change their color as a function of
temperature and pressure. Furthermore, pressure sensors constructed
in such a manner can be calibrated to record pressure changes from
zero to 500 pounds. The chlorine sensor 108, the temperature sensor
109 and the pressure sensor 110 are attached and positioned between
two sheets 102, 104 and spaced apart so that the skin surface of
the patient is sufficiently monitored so that no bed sores can
develop. The pressure sensor 110 may have a threshold measurement
of 80 g/cm.sup.2 which translates to 0.011384 psi, and other
thresholds may work equally well. The sheets 102, 104 may be
positioned on a conventional mattress so that the patient can be
monitored while lying down. Alternatively, the sheets 102, 104 may
be positioned in a chair, sofa, wheelchair or any other device in
which the patient may be placed and develop such conditions. The
sheets 102,104 may be formed from plastic or from any other
suitable material.
[0024] FIG. 1 additionally shows a connector socket 106 attached to
one or both of the sheets 102, 104 for a common connection point
for the wires 112 which are connected to the sensors 108,109, 110
and which are used to carry the information in the form of sensor
signals from the sensors 108,109, 110. The sensors 108, 109, and
110 may communicate with the signal conditioning and data transfer
unit 114 wirelessly to eliminate the connector socket 106, wires
112 and the serial connection 116 which is used to connect the
connector socket 106 with a signal conditioning and data transfer
unit 114.
[0025] The single conditioning and data transfer unit 114 obtains
sufficient information from the patient by the chlorine sensor 108,
the temperature sensor 109 and the pressure sensor 110 to determine
if bed sores are developing. Other types of sensors are within the
scope of the present invention in order to achieve the desired
results. FIG. 1 additionally shows the sensor system 100 including
a first subsystem 120 of sheets 102, 104, sensors 108, 110, 112,
and signal conditioning and data transfer unit 114 and a second
subsystem 122 of sheets 102, 104, sensors 108, 110, 112, and signal
conditioning and data transfer unit 114. Each of the subsystems
120, 122 could be for an individual patient. The subsystems 120,
122 could be expanded to any number of subsystems and any number of
individual patients. FIG. 1 shows sheets 102, 104 laid flat for use
with a mattress; however, the sheets 102, 104 could be for use with
a chair, a wheelchair or any other article which a patient has
contact with or integral with the material.
[0026] The sheets 102, 104 are shown as rectangles which may be
sized to be used with a mattress, but other sizes and shapes for
the sheets 102, 104 are possible based on the needs of the patient
and the device that the patient is positioned in. The sensors could
be directly mounted on the patient for example while lying on the
patient's back for example, while in ICU or could used with other
applications such as car seats, airplane seats or other
applications.
[0027] FIG. 2 illustrates a block diagram of the signal
conditioning and data transfer unit 114 which includes a controller
206 to receive the sensor signals from the sensors 108, 110 and
112, and make the necessary calculations in order to determine if
bed sores are developing with any of the patients being monitored
and stores the sensor signals in the RAM 208. Additionally, the
controller 206 receives the sensor signals from each suite of
sensors 108,109, 110 of subsystems 120, 122. The controller 206 is
connected to a serial connection 116 or alternatively to a wireless
connection 204 to receive sensor signals from the sensors 108,109,
110. LCD display 210 is connected to the controller 206 to display
the information collected and computed by the controller 206; LED
display 212 is connected to controller 206 to display status
information of the various hardware devices connected to the
controller 206 and to provide a status indication of equipment,
such as the sensors, and an alarm unit 214. The signal conditioning
and data transfer unit 114 communicates with the central monitoring
station 140 which includes an input output device 130 for
communication and which is used to monitor other signal
conditioning and data transfer units 114 at different locations.
Typically, the central monitoring station 140 would be a central
computer for a nursing home or a hospital or any such institution.
Alternatively, the central monitoring station 140 could be shared
among a group of small institutions. The input/output device 130
could include a computer keyboard and computer monitor and
alternatively an antenna 304 for wireless communication or could be
connected by a cable such as a USB connection 302. Like the signal
conditioning and data transfer unit 114, the central monitoring
station 140 includes a controller 306 to provide for calculation
and control of the signal conditioning and data transfer unit 114,
a RAM 308 for data storage of information, a LCD display 310 to
display condition results, LED lights 312 to indicate status
information and an alarm 314 to indicate when a situation develops
that could harm the patient for example the development of a bed
sore.
[0028] In operation, a patient is positioned between sheet 102 and
sheet 104, and the chlorine sensor 108, the temperature sensor 109
and the pressure sensor 110 are positioned on one or both of the
sheets 102, 104 but most likely would be located on the bottom
sheet. The chlorine sensor 108, the temperature sensor 109 and the
pressure sensor 110 continuously or intermittently sense the
conditions of the patient and sends a sensor signal along wires 112
to the connector 106 and to the serial connector 116, and the
sensor signal reaches the signal conditioner and data transfer unit
114. The signal conditioner and data transfer unit 114 receives the
sensor signals from the chlorine sensor 108, the temperature sensor
109 and the pressure sensor 110.
[0029] The sensor signals are sent to RAM 208 for storage and then
to the controller 206 for evaluation. If the controller 206
determines that conditions are favorable for the development of bed
sores for example by determining that the one or more of the sensor
signals have exceed a predetermined threshold, then the controller
206 activates the alarm 214. The predetermined threshold is stored
in RAM 208 to be accessed by the controller 206 and may be stored
for each of the individual patients and for each sensor
108,109,110. The controller 206 may send an alarm and/or the sensor
signals to the central monitoring station 140. The controller 206
obtains data from the RAM 208 to evaluate the sensor signals sent
from the chlorine sensor 108, the temperature sensor 109 and the
pressure sensor 110. If the controller 206 does not for example
received a sensor signal from one of the sensors, then the
controller 206 activates the alarm 214 so that the defective sensor
can be fixed or replaced. The LCD display 210 can display the
sensor signals from the chlorine sensor 108 the temperature sensor
109 or/and the pressure sensor 110. Additionally, the LCD display
110 can display the evaluation of the sensor signals by the
controller 206 so that the patient or staff member for the patient
can determine if conditions favorable for bed sores are being
approached. The LED display 212 can display which sensors are
active and which sensors are inactive.
[0030] The signal conditioning and data transfer unit 114 transmits
the sensor signals to the central monitoring station 140 through
the input and output unit 130. The central monitoring station 140
may be at a physically different location than the signal
conditioning and data transfer unit 114 so that the personnel at
the location of the central monitoring station 140 can monitor the
patient from a remote location. The signal conditioning and data
transfer unit 114 can change the thresholds used by the signal
conditioning and data transfer unit 114 in the comparison of the
sensor signals from the chlorine sensor 108, the temperature sensor
109 and the pressure sensor 110 for the determination of favorable
conditions for the development of bed sores. Consequently, the
signal conditioning and data transfer unit 114 can take into
account the different tolerances of different patients for
favorable conditions for the development of the bed sores.
Furthermore, the controller 206 can store the readings from the
chlorine sensor 108, the temperature sensor 109 and the pressure
sensor 110 in RAM 208 so that evaluations of the patient can be
achieved based on previous history sensor readings. The chlorine
ion sensor 108 as shown in FIG. 4, element 404 may be constructed
using Sn-doped silica gels, and these gels respond to the presence
of chlorine ions by undergoing chemical changes that can be
monitored electrochemically. More particularly, when the gels are
exposed to chlorine ions, the electrical properties of the Sn-doped
gels change, and the resistance of the gel correspondingly changes
to allow more or less current to flow through the gel. This aspect
is capitalized on by forming the sensor 108 such that the sensor
108 sequesters chlorine ions from the environment of the sensor 108
as a result of the positive charge associated with the chlorine
ions and the affinity of Sn for chlorine.
[0031] FIG. 5 shows the change in current with respect to the
changing chloride concentration. This graph represents a
substantially linear relationship, showing as the chlorine
concentration increasing by powers of 10 and the current flow
correspondingly increasing.
[0032] FIG. 6 illustrates additional details of the pressure sensor
110 which includes a first electrode 602 and a second electrode 604
to allow electrical connection with the pressure sensor 110. The
first electrode 602 is connected to foil 606, and the second
electrode 604 is connected to foil 610. The first foil 606 and the
second foil 610 are formed around a layer of sol-gel 608. The
compression of the sol-gel layer 608 generates an electrical
potential between the first and second electrode 602, 604.
[0033] The following is a description of one method of the several
methods of forming the chlorine sensor 108. The steps of this
method are shown in FIG. 8. The sensor 108 includes films to form
the coating on surface of the sensor 108. It should be noted that
all times and concentrations may be approximate, and other methods
may yield equally satisfactory results. To prepare the Sn/SiO.sub.2
films used in the chlorine sensor 108, approximately 0.7011 gm
SnCl.sub.4 and 5H.sub.2O is added to 750 ul of water, resulting in
a concentration of 2.6 M in step 802. The precursor used in step
804 for the sol-gel coating is Tetra Methoxy Silane (TMOS), and 461
ul of TMOS is added to the mixture. The resulting concentration of
TMOS in the sol is 2.56 M. The mixture is sonicated in step 804 for
approximately 20 minutes in a polystyrene beaker covered with a
Para film. After sonication, a homogeneous mixture is obtained. A
solution of 2.5% Poly Vinyl alcohol in water (25 .mu.l) is added in
step 808 to the sol solution to prevent cracking of the gel
coating.
[0034] The thin coating of the sol on the electrodes 402 is
achieved with a spin coater. Here, 250 .mu.l of the homogeneous sol
is taken and applied to a circular surface of the electrode 402.
The electrode 402 is placed on the spin coater, and a homogeneous
thin coating is obtained by this process. All the sol-gel
electrodes are left to dry under room conditions for approximately
12 hours before use. The electrodes are subsequently washed with
water (50 mL) to get rid the electrodes 402 of any Cl.sup.-
ions.
[0035] The steps of electrode preparation are shown in FIG. 9. The
sensor is constructed by depositing film in step 902 of the Sn:
SiO.sub.2 sol-gel on a 1 cm.sup.2 circular polystyrene plate which
is sputter coated with gold. Spin Coating technique is used to
deposit the sol-gel thin films on the gold coated electrode
surface. On to this film, a small Pt wire and Ag/AgCl electrode are
placed using a conducting silver glue as in step 904. The working
electrode has an area of approximately 1 cm.sup.2 for measurements
in this example. All the sol-gel electrodes are left to dry in step
906 under room conditions for approximately 12 hours before use.
The electrodes are then washed in step 908 with water (50 ml) to
get rid of any Cl.sup.- ions.
[0036] The sensor may be calibrated by the following
electrochemical measurements by which measurements could be taken
in a 3-electrode configuration. The electrode is immersed in a
given concentration of chloride ions and current is monitored using
chromoamperometry. The saturation current is measured at 1 V
applied potential or any other appropriate potential. The current
is correlated with concentration of the chloride ion in the
surrounding liquid.
[0037] The pressure sensor 110 can be of many types. One type of
pressure sensor 110 is based on converting the pressure exerted on
the pressure sensor 110 to an electrical signal which is
transmitted to the signal conditioning and data transfer unit 114.
Another type of pressure sensor changes color in response to the
pressure being exerted on the pressure sensor 110.
[0038] With the present invention, elastic sol-gels or silicones
are impregnated with conducting particles such as carbon powder or
metal particles that are used to change the resistance of the
sol-gel and consequently the current varies based on changes of
pressure on the pressure sensor 110. These types of gels shrink or
contract as pressure is applied to the pressure sensor 110,
increasing the density of the conducting particles and lowering the
resistance of the sol-gel.
[0039] FIG. 7 illustrates the relationship between the pressure
shown as weight and the pressure signal shown as the current.
[0040] In a similar fashion as the chlorine sensor 108, the
pressure sensor 110 is formed as follows as shown in FIG. 10. The
conducting sol-gels are prepared by mixing 8 ml methanol with 1.4
ml of Bis[3-(trimethoxy-silyl)propyl]ethylenediamine (EnTMOS)
precursor and 0.4 ml H.sub.2O in step 1002. The mixture is
sonicated in step 1004 for approximately 30 minutes to form a
homogenous sol. To this sol, about 0.3 g of the conducting
particles for example graphite powder, alfa aesar, synthetic,
conducting grade, (.about.200 mesh) is added in step 1006 to impart
conductivity. The sol is then placed in a polystyrene curette to
form circular disks as in step 1008 with an approximate diameter of
about 1 inch and thickness ranging from 0.5 to 1 cm. The top and
bottom of the gels are then connected with silver foil electrodes
in a sandwich type configuration. The silver foils are connected in
step 1010 to the gels by means of a conducting silver paste. Next,
the sample is calibrated by the following steps. The silver foils
are connected to a potentiostat for measuring current across the
sample. Chromoamperometry is used to measure current at 0.5 V. The
current flowing though the sample is measured as a function of
weights placed on the gels. The device of the present invention can
be modified to check or sense one or all of the following including
pulse rate, oxygen saturation and temperature simultaneously. These
sensors could use wired or wireless technology to send an
activation signal to the sensor which responds to the activation
signal by transmitting the sensor signal to be displayed on a
screen at the nursing station. When a physician makes his/her
rounds, the physician can quickly obtain the vital signs by looking
on the screen.
[0041] While the above embodiments of the present invention have
been described in a particular manner, one of ordinary skill in the
art would recognize that substitutions and modifications would be
contemplated with the teachings of the present invention. Thus,
other modifications and substitutions are within the scope of the
present invention.
* * * * *
References