Handheld sensing apparatus

• US 20020124631A1
• Filed: 03/15/2002
• Published: 09/12/2002
• Est. Priority Date: 03/20/1998
• Status: Active Grant

• Current Assignee: Smiths Detection Incorporated
• Original Assignee: Cyrano Sciences, Inc. (Smiths Detection-Watford Ltd.)
• Inventors: Sunshine, Steven A., Steinthal, M. Gregory, Boehr, Christopher K., Nakayama, Robert K.
• Granted Patent: US 6,658,915 B2
• Time in Patent Office: Days
• US Class Current: 73/23.2
• CPC Class Codes: G01N 33/0009 General constructional details of gas analysers, e.g. portable test equipment G01N1/22 takes precedence
• CPC Class Codes: G01N 33/0031 comprising two or more sensors, e.g. a sensor array electrochemical electrode arrays G01N27/27

Abstract

A vapor sensing device that is sufficiently small and lightweight to be handheld, and also modular so as to allow the device to be 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.

Claims

1. A handheld sensing apparatus comprising:

a housing;

a sensor module mounted in the housing and including at least two sensors that provide a distinct response to a particular test sample;

a sample chamber defined by one or both of the housing and the sensor module, the sample chamber incorporating an inlet port and an outlet port, wherein the at least two sensors are located within or adjacent to the sample chamber; and

an analyzer mounted in the housing and configured to analyze a particular response from the at least two sensors, wherein the analyzer identifies or quantifies analytes within the test sample based on the particular response.

2. The handheld sensing apparatus of claim 1 further comprising:

a pump mounted in the housing and configured to direct the particular test sample through the sample chamber, from the inlet port to the outlet port.

3. The handheld sensing apparatus of claim 1 wherein the particular response includes a set of signals indicative of changes in resistances of the at least two sensors due to exposure to the particular test sample.

4. The handheld sensing apparatus of claim 1 further comprising:

measurement circuitry mounted in the housing and configured to detect the distinct response from the at least two sensors and to provide a sensed signal corresponding the distinct response.

5. The handheld sensing apparatus of claim 4 wherein the measurement circuitry includes a sigma-delta converter.

6. The handheld sensing apparatus of claim 1 wherein the analyzer receives the distinct response from the at least two sensors and generates a corresponding signature.

7. The handheld sensing apparatus of claim 6 wherein a plurality of reference signatures is collected for a plurality of reference samples and a sample signature is generated for the particular test sample, and wherein the analyzer is configured to compare the sample signature against the plurality of reference signatures to identify the particular test sample.

8. The handheld sensing apparatus of claim 1 further comprising:

a valve mounted in the housing and configured to direct either a reference sample or an unknown test sample to the sample chamber.

9. The handheld sensing apparatus of claim 8 wherein the reference sample is preconditioned.

10. The handheld sensing apparatus of claim 8 wherein the reference sample is selected from among a plurality of reference samples.

11. The handheld sensing apparatus of claim 1 wherein the sample chamber is sealed from external environment, except for the inlet port and the outlet port.

12. The handheld sensing apparatus of claim 1 further comprising a preconcentrator.

13. The handheld sensing apparatus of claim 1 further comprising:

thermal control circuitry that controls the temperature of the at least two sensors.

14. The handheld sensing apparatus of claim 1 wherein at least one of the sensors in the sensor module is a member selected from the group consisting of a conducting/nonconducting regions sensor, a SAW sensor, a quartz microbalance sensor, a conductive composite sensor, a chemiresitor, a metal oxide gas sensor, an organic gas sensor, a MOSFET, a piezoelectric device, an infrared sensor, a sintered metal oxide sensor, a Pd-gate MOSFET, a metal FET structure, a electrochemical cell, a conducting polymer sensor, a catalytic gas sensor, an organic semiconducting gas sensor, a solid electrolyte gas sensors, and a piezoelectric quartz crystal sensor.

15. The handheld sensing apparatus of claim 14 wherein at least one of the sensors in the sensor module is a conducting/nonconducting regions sensor.

16. The handheld sensing apparatus of claim 14 wherein at least one of the sensors in the sensor module is a SAW sensor.

17. The handheld sensing apparatus of claim 1 wherein the sensor module includes:

a plurality of sensor array devices, each sensor array device including an array of sensors.

19. The handheld sensing apparatus of claim 18 further comprising:

one or more additional sensor modules, each sensor module configured to be removably mounted in the receptacle and to incorporate at least one sensor, wherein each sensor module is configured to provide a different set of responses to a set of distinctive samples.

20. The handheld sensing apparatus of claim 19 wherein each removably mounted sensor module includes an identifier for identifying the sensor module, and wherein the analyzer is configured to determine the identifier included in the particular sensor module received in the receptacle.

18. A handheld sensing apparatus comprising:

a housing including a receptacle;

a sensor module removably mounted in the receptacle of the housing, the sensor module including at least one sensor that provides a distinct response to a particular test sample;

a sample chamber defined within the sensor module, the sample chamber incorporating an inlet port and an outlet port, wherein the at least one sensors is located within or adjacent to the sample chamber; and

an analyzer mounted in the housing and configured to analyze a particular response from the at least two sensors, wherein the analyzer identifies or quantifies analytes within the test sample based on the particular response.

21. A sensor module configured for use with a sensing apparatus disposed within a housing that defines a receptacle, the sensor module comprising:

a casing sized and configured to be received in the receptacle of the sensing apparatus;

a sample chamber;

an inlet port configured to be releasably engageable with a first port connection of the sensing apparatus when the sensor module is received in the receptacle, the inlet port receiving a test sample from the sensing apparatus and directing the test sample to the sample chamber;

an outlet port configured to discharge the test sample from the sample chamber;

at least one sensor located within or adjacent to the sample chamber and configured to provide a distinct response when exposed to one or more analytes located within the sample chamber; and

an electrical connector configured to be releasably engageable with a mating electrical connector of the sensing apparatus when the sensor module is received in the receptacle, the electrical connector transmitting the characteristic signals from the at least one sensor to the sensing apparatus.

22. The sensor module of claim 21 wherein the outlet port is configured to be releasably engageable with a second port connection of the sensing apparatus when the sensor module is received in the receptacle of the sensing apparatus, the outlet port discharging the test sample from the sample chamber to the sensing apparatus.

23. The sensor module of claim 22 wherein the casing incorporates a rear wall that supports the inlet port, the outlet port, and the electrical connector.

24. The sensor module of claim 21 further comprising:

a substrate to which the plurality of sensors mounts.

25. The sensor module of claim 21 wherein the at least one sensor is arranged in a uniform manner within the sample chamber.

26. The sensor module of claim 21 wherein

each of the at least one sensor is implemented with a chemically sensitive resistor having a resistance that varies in a unique manner when exposed to one or more specified test samples;

and

the sensing apparatus includes an analyzer that detects a set of resistances of the at least one sensor and identifies the test sample based on the detected set of resistances.

28. The handheld sensing apparatus of claim 27 wherein the conditioning circuitry includes a set of voltage divider networks, one network for each of the at least two chemically sensitive resistors, each network providing an analog voltage.

29. The handheld sensing apparatus of claim 27 further comprising:

at least one multiplexer coupled to the set of voltage divider networks, the multiplexer coupling the analog voltage from the set of voltage divider networks to the ADC.

30. The handheld sensing apparatus of claim 29 further comprising:

at least one amplifier, each amplifier coupled between one multiplexer and the ADC.

27. A handheld sensing apparatus for measuring the concentration of one or more analytes within a sample chamber, comprising:

at least two chemically sensitive resistors, each chemically sensitive resistor having a resistance that varies according to a concentration of one or more analytes within the sample chamber;

conditioning circuitry coupled to the at least two chemically sensitive resistors, the conditioning circuitry generating an analog signal indicative of the resistance of each of the at least two chemically sensitive resistors;

an analog-to-digital converter (ADC) coupled to the conditioning circuitry, the ADC responsive to the analog signal and providing a digital signal; and

an analyzer coupled to the ADC, the analyzer responsive to the digital signal and determining the identity or concentration of one or more analytes within the sample chamber.

31. A hand-held vapor sensing apparatus, comprising:

a hand-held housing;

a sensor module mounted in the housing and incorporating a plug-in array of vapor sensors, each vapor sensor providing a different electrical response to one or more distinct vapors;

wherein one or both of the housing and the sensor module define a sample chamber to which the array of vapor sensors of the sensor module is exposed, the sample chamber incorporating a vapor inlet and a vapor outlet;

a pump mounted on the housing and configured to direct a vapor sample through the sample chamber, from the vapor inlet to the vapor outlet;

a monitoring device mounted on the housing and configured to monitor the electrical responses of the array of vapor sensors incorporated in the sensor module, and further configured to produce a corresponding plurality of sensor signals; and

an analyzer mounted on the housing and configured to analyze the plurality of sensor signals, to identify any vapor sample directed through the sample chamber by the pump.

32. A plug-in sensor module configured for use with a hand-held vapor sensing apparatus of a kind including a hand-held housing that defines a receptacle, the sensor module comprising:

a casing sized and configured to be received in the receptacle of the hand-held vapor sensing apparatus;

a sample chamber;

a vapor inlet configured to be releasably engageable with a first vapor connection of the hand-held vapor sensing apparatus when the plug-in sensor module is received in the receptacle of the vapor sensing apparatus, for receiving a vapor sample from the vapor sensing apparatus and directing the vapor sample to the sample chamber,

a vapor outlet configured to discharge the vapor sample from the vapor chamber; and

a plurality of vapor sensors located within or adjacent to the sample chamber and configured to provide different electrical signals in response to one or more vapors located within the sample chamber;

an electrical connector configured to be releasably engageable with a mating electrical connector of the hand-held vapor sensing apparatus when the plug-in sensor module is received in the receptacle of the vapor sensing apparatus, to transmit electrical signals from the plurality of vapor sensors to the vapor sensing apparatus.

33. A vapor sensing apparatus for measuring the concentration of one or more prescribed vapors within a sample space, comprising:

a chemically sensitive resistor having a resistance that varies according to the concentration of one or more prescribed vapors within a sample space;

a reference resistor connected in series with the chemically sensitive resistor, between a reference voltage source and ground, such that an analog output signal is established at the node between the reference resistor and the chemically sensitive resistor;

an analog-to-digital converter, responsive to both the analog output signal and the voltage level of the reference voltage source, for producing a digital output signal indicative of the resistance of the chemically sensitive resistor; and

an analyzer, responsive to the digital output signal, for determining the concentration of one or more prescribed vapors within the sample space;

wherein the vapor sensing apparatus is configured such that variations in the voltage level of the reference voltage source will have only an insubstantial effect on the value of the digital output signal.