Systems and methods for detecting change in species in an environment
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.
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, wherein the sensor comprises a PIN diode;
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 predetermined frequency range comprises an infrared (IR) frequency range.
3. The method of claim 1 , wherein the analyte comprises a polar molecule.
4. 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.
5. The method of claim 4 further comprising determining a concentration of the analyte from the capacitance difference at the discrete frequencies over the predetermined frequency range.
6. The method of claim 1 , wherein determining a difference further comprises storing the difference and the discrete frequency.
7. The method of claim 1 , wherein the analyte is a gas.
8. 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.
9. The method of claim 8 , 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.
10. 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, wherein the capacitive sensor comprises a PIN diode;
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.
11. The method of claim 10 , wherein the analyte comprises a polar molecule.
12. The method of claim 10 , 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.
13. The method of claim 12 further comprising determining a concentration of the analyte from the capacitance difference at the discrete frequencies over the infrared frequency range.
14. The method of claim 10 , wherein the analyte is a gas.
15. The method of claim 10 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.
16. 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, wherein the capacitive sensor comprises a PIN diode;
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.
17. The method of claim 16 , 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.
18. The method of claim 16 , wherein the predetermined frequency range comprises an infrared (IR) frequency range.