Interdigitated capacitive sensor for real-time monitoring of sub-micron and nanoscale particulate matters

Patent metadata

Field	Value
Publication number	US-11650144-B2
Application number	US-202117173877-A
Country	US
Kind code	B2
Filing date	Feb 11, 2021
Priority date	Feb 11, 2020
Publication date	May 16, 2023
Grant date	May 16, 2023

Abstract

Aspects of the present disclosure involve systems, methods, and the like, for a fabrication of a particulate matter (PM) sensor that utilizes a capacitance sensor to detect sub-micrometer and nanoparticles in the respirable range of an environment. In one implementation, the capacitance sensor may comprise interdigitated electrodes between which a capacitance may be measured. PM deposited on the sensor may cause the capacitance between the electrodes to be altered and such a change in capacitance may be measured by the PM sensor. This measurement of the change in capacitance of the interdigitated capacitance sensor may therefore be correlated to the presence of sub-micrometer and nanoparticles in an environment. In one particular implementation, the PM sensor may further include a micro-heater circuit, a readout circuit, and an interface connecting the readout circuit to the micro-heater/capacitance sensor of the PM sensor.

First claim

We claim:

1. A particulate matters sensing device comprising:
a sensor cartridge comprising:
an interdigitated capacitance sensor comprising a plurality of interdigitated electrodes, each of the plurality of interdigitated electrodes separated from another of the plurality of interdigitated electrodes by a spacing, wherein sub-micron or nanoscale particular matters (PMs) of an environment are deposited within the spacing; and

a readout circuit comprising:
a processor; and
a tangible storage medium encoded with instructions that are executed by the processor to perform operations comprising:
receiving, from a monitoring circuit, a measurement signal comprising a delay of a monitoring signal;
comparing the measurement signal to the monitoring signal to determine the capacitance of the interdigitated capacitance sensor;
correlating the capacitance of the interdigitated capacitance sensor to a concentration of the deposited sub-micron or nanoscale PMs of the environment; and
displaying an indication of the concentration of the deposited sub-micron or nanoscale PMs of the environment.

2. The particulate matters sensing device of claim 1 wherein the sensor cartridge further comprises a micro-heater circuit generating heat for the sensor cartridge.

3. The particulate matters sensing device of claim 1 wherein the readout circuit further comprises a display device, the instructions further executed to perform the operation of:
displaying the indication of the concentration of the deposited sub-micron or nanoscale PMs of the environment on the display device.

4. The particulate matters sensing device of claim 1 wherein the readout circuit further comprises a wireless communication unit receiving the indication of the concentration of the deposited sub-micron or nanoscale PMs of the environment and transmitting the indication via the wireless communication unit.

5. The particulate matters sensing device of claim 1 wherein a width of at least one of the plurality of electrodes is between 10 nm to 3 μm and a width of the spacing is between 10 nm to 3 μm.

6. The particulate matters sensing device of claim 1 wherein the sensor cartridge further comprises a flexible, printed circuit board comprising a first conductive path electrically connected to a first portion of the plurality of interdigitated electrodes and a second conductive path electrically connected to a second portion of the plurality of interdigitated electrodes.

7. The particulate matters sensing device of claim 1 wherein the sensor cartridge further comprises the monitoring circuit comprising a resistor connected in series with the interdigitated capacitance sensor, the resistor and interdigitated capacitance sensor comprising a resistor-capacitor (RC) circuit.

8. The particulate matters sensing device of claim 7 wherein the instructions are further executed to perform the operation of:
transmitting the monitoring signal to the RC circuit, the RC circuit providing an output signal comprising the delay of the monitoring signal, the delay corresponding to the capacitance of the interdigitated capacitance sensor of the RC circuit.

9. The particulate matters sensing device of claim 1 the indication of the concentration of the deposited sub-micron or nanoscale PMs of the environment comprises at least one of an auditory alarm, a tactile alarm, or a visual alarm.

10. A method for monitoring particulate matters of an environment, the method comprising:
locating a sensor cartridge in a sampling cassette, the sensor cartridge comprising an interdigitated capacitance sensor comprising a plurality of interdigitated electrodes, each of the plurality of interdigitated electrodes separated from another of the plurality of interdigitated electrodes by a spacing;
determining, at a monitoring circuit, a delay of a monitor signal indicating a capacitance of the interdigitated capacitance sensor, the capacitance corresponding to a concentration of deposited sub-micron or nanoscale PMs of the environment on the spacing of the interdigitated capacitance sensor; and
displaying, on a display device, an indication of the concentration of the deposited sub-micron or nanoscale PMs of the environment on the spacing of the interdigitated capacitance sensor.

11. The method of claim 10 wherein the sensor cartridge further comprises a resistor connected in series with the interdigitated capacitance sensor, the resistor and interdigitated capacitance sensor comprising a resistor-capacitor (RC) circuit, the method further comprising: transmitting a monitor signal to the RC circuit.

12. The method of claim 11 further comprising:
receiving a measurement signal comprising the delay of the monitor signal, the delay corresponding to the capacitance of the interdigitated capacitance sensor.

13. The method of claim 12 further comprising:
determining a number of output pulses of the measurement signal with a duration equal to or more than a minimum duration value.

14. The method of claim 13 further comprising:
correlating the number of output pulses of the measurement signal to the concentration of deposited sub-micron or nanoscale PMs of the environment on the spacing of the interdigitated capacitance sensor.

15. The method of claim 14 wherein correlating the number of output pulses of the measurement signal to the concentration of deposited sub-micron or nanoscale PMs of the environment comprises accessing a look-up table from a memory device.

16. The method of claim 12 further comprising:
comparing an output signal of an inverter of the monitoring circuit to the monitoring circuit to generate the measurement signal comprising the delay of the monitor signal.

17. The method of claim 10 further comprising: transmitting, via a wireless transmitter, the indication of the concentration of the deposited sub-micron or nanoscale PMs of the environment.

18. The method of claim 10 wherein the sensor cartridge further comprises a micro-heater circuit generating heat for the sensor cartridge.

19. The method of claim 10 wherein a width of at least one of the plurality of electrodes is between 10 nm to 3 μm and a width of the spacing is between 10 nm to 3 μm.

Assignees

• Univ Colorado State Res Found
• Purdue Research Foundation

Inventors

• Tsai Su-Jung (Candace)
• Back Doosan
• Janes David B

Classifications

• G01N2015/0038

  Investigating nanoparticles · CPC title

• G01N15/0656

  using electric, e.g. electrostatic methods or magnetic methods (by investigating individual particles G01N15/1031, G01N15/12) · CPC title

• G01N2015/0046

  in gas, e.g. smoke · CPC title

• G01N15/0606 Primary

  by collecting particles on a support · CPC title

• G01N15/10 Primary

  Investigating individual particles · CPC title