Systems and methods for detecting change in species in an environment

Patent metadata

Field	Value
Publication number	US-2016238580-A1
Application number	US-201514837147-A
Country	US
Kind code	A1
Filing date	Aug 27, 2015
Priority date	Feb 18, 2015
Publication date	Aug 18, 2016
Grant date	—

Abstract

A method for determining the concentration of an analyte is provided. The method comprises: applying an alternating voltage to a first electrode and a second electrode of a sensor in the presence of the analyte; measuring a first capacitance of the sensor in presence of the analyte; irradiating the analyte for a predetermined time period at a discrete frequency within a predetermined frequency range; measuring a second capacitance of the sensor at an end of the predetermined time period; determining a difference between the first and second capacitances; and determining the concentration of the analyte based on the difference. Also, the method includes determining a composition of an analyte. The discrete frequency is associated with the difference to determine a frequency response. The frequency response is used to determine the composition of the analyte.

First claim

What is claimed:

1 . A method for determining a concentration of an analyte, the method comprising:
applying an alternating voltage to a first electrode and a second electrode of a sensor in the presence of the analyte; measuring a first capacitance of the sensor in presence of the analyte; irradiating the analyte for a predetermined time period at a discrete frequency within a predetermined frequency range; measuring a second capacitance of the sensor at an end of the predetermined time period; determining a difference between the first and second capacitances; and determining the concentration of the analyte based on the difference.

2 . The method of claim 1 , wherein the sensor comprises a PIN diode.

3 . The method of claim 1 , wherein the predetermined frequency range comprises an infrared (IR) frequency range.

4 . The method of claim 1 , wherein the analyte comprises a polar molecule.

5 . The method of claim 1 , further comprising iteratively performing the steps of measuring a first capacitance, irradiating the analyte, measuring a second capacitance, and determining a difference at different discrete frequencies until the predetermined frequency range has been sampled.

6 . The method of claim 5 further comprising determining a concentration of the analyte from the capacitance difference at the discrete frequencies over the predetermined frequency range.

7 . The method of claim 1 , wherein determining a difference further comprises storing the difference and the discrete frequency.

8 . The method of claim 1 , wherein the analyte is a gas.

9 . The method of claim 1 further comprising:
associating the discrete frequency with the difference to determine a frequency response; and
using the frequency response to determine a composition of the analyte.

10 . The method of claim 9 , wherein using the frequency response to determine the composition of the analyte further comprises matching the frequency response with the analyte in a look-up table.

11 . A method for determining a concentration of an analyte, the method comprising:
applying an alternating voltage to a first electrode and a second electrode of a capacitive sensor in the presence of the analyte; measuring a first capacitance of the capacitive sensor in presence of the analyte; irradiating the analyte for a predetermined time period at a discrete frequency within an infrared frequency range; measuring a second capacitance of the capacitive sensor at the end of the predetermined time period; determining a difference between the first and second capacitances; and determining the concentration of the analyte based on the difference.

12 . The method of claim 11 , wherein the analyte comprises a polar molecule.

13 . The method of claim 11 , wherein the capacitive sensor comprises a PIN diode.

14 . The method of claim 11 , further comprising iteratively performing the steps of measuring a first capacitance, irradiating the analyte, measuring a second capacitance, and determining a difference at different discrete frequencies until a complete range of the infrared frequency range has been sampled.

15 . The method of claim 14 further comprising determining a concentration of the analyte from the capacitance difference at the discrete frequencies over the infrared frequency range.

16 . The method of claim 11 , wherein the analyte is a gas.

17 . The method of claim 11 further comprising:
associating the discrete frequency with the difference to determine a frequency response; and
using the frequency response to determine a composition of the analyte.

18 . A method for determining a composition and concentration of an analyte, the method comprising:
applying an alternating signal to a first electrode and a second electrode of a sensor in the presence of the analyte; measuring a first capacitance of the sensor in presence of the analyte; irradiating the analyte for a predetermined time period at a discrete frequency within a predetermined frequency range; measuring a second capacitance of the sensor at the end of the predetermined time period; determining a difference between the first and second capacitances; determining the concentration of the analyte based on the difference; associating the discrete frequency with the difference to determine a frequency response; and using the frequency response to determine the composition of the analyte.

19 . The method of claim 18 , further comprising iteratively performing the steps of measuring a first capacitance, irradiating the analyte, measuring a second capacitance, and determining a difference at different discrete frequencies until a complete range of the infrared frequency range has been sampled.

20 . The method of claim 18 , wherein the predetermined frequency range comprises an infrared (IR) frequency range.

Assignees

• Freescale Semiconductor Inc

Inventors

• Kundalgurki Srivatsa G

Classifications

• G01N33/0062 Primary

  concerning the measuring method or the display, e.g. intermittent measurement or digital display · CPC title

• G01N27/228

  Circuits therefor (measuring capacitance per se G01R27/26) · CPC title

• G01N33/0036

  specially adapted to detect a particular component (physical analysis of gaseous biological material G01N33/497) · CPC title

• G01N27/227

  Sensors changing capacitance upon adsorption or absorption of fluid components, e.g. electrolyte-insulator-semiconductor sensors, MOS capacitors (G01N27/225 takes precedence) · CPC title