Miniaturized thermal acoustic gas sensor based on a CMOS microhotplate and MEMS microphone

Abstract

We present a miniaturised thermal acoustic gas sensor, fabricated using a CMOS microhotplate and MEMS microphone. The sensing mechanism is based on the detection of changes in the thermal acoustic conversion efficiency which is dependent on the physical properties of the gas. An active sensing element, consisting of a MEMS microphone, is used to detect the target gas while a reference element is used for acoustic noise compensation. Compared to current photoacoustic gas sensors, our sensor requires neither the use of gas-encapsulated microphones, nor that of optical filters. In addition, it has all the benefits of CMOS technology, including production scalability, low cost and miniaturization. Here we demonstrate its application for CO$$_2$$ 2 gas detection. The sensor could be used for gas leak detection, for example, in an industrial plant.

Significance of Various Sensing Mechanisms for Detecting Local and Atmospheric Greenhouse Gases: A Review

“…Table 1 delineates the materials incorporated into the gas-sensing devices, as described in Section 3 of this work, and provides the disadvantages that more commonly occur according to the configuration or mechanisms of action of any of the described gas sensors. [71,[108][109][110][111]140] Irrespective of this feasibility afforded to monitor the germinating GHGs with operational, research-grade instrumentation, still, quantification requirements must be carefully construed. For instance, data records should be exceptionally precise, durable, and span multiple decades for the long-term resolution of annual mean GHG gradients.…”

“…Table 1 delineates the materials incorporated into the gas‐sensing devices, as described in Section 3 of this work, and provides the disadvantages that more commonly occur according to the configuration or mechanisms of action of any of the described gas sensors. [ 71,108–111,140 ]…”

Highly Sensitive Low-Frequency-Detectable Acoustic Sensor Using a Piezoresistive Cantilever for Health Monitoring Applications

“…Microphones, which convert sound waves to electrical signals, are indispensable in various applications, such as consumer electronics [1][2][3][4][5] , automobiles 6 , hearing aid devices 7,8 , wearable health monitoring [9][10][11][12][13][14][15][16][17][18][19] , photoacoustic-based gas sensing [20][21][22][23][24][25] , and the monitoring of natural disasters, such as volcanic eruptions [26][27][28] , debris flow 29 , and earthquakes 30 . Two widely used types of microphones exist, traditional electret condenser and microelectromechanical systems (MEMS)-based microphones.…”

Highly sensitive low-frequency-detectable acoustic sensor using a piezoresistive cantilever for health monitoring applications

“…We believe the proposed microphone will be used in various applications, such as wearable health monitoring, monitoring of natural disasters, and realization of high-resolution photoacoustic-based gas sensors. We successfully measured the first (S1) and second (S2) cardiac sounds with frequencies of 7-100 Hz and 20-45 Hz, respectively.Microphones, which convert sound waves to electrical signals, are indispensable in various applications, such as consumer electronics 1-5 , automobiles 6 , hearing aid devices 7,8 , wearable health monitoring 9-19 , photoacousticbased gas sensing [20][21][22][23][24][25] , and the monitoring of natural disasters, such as volcanic eruptions [26][27][28] , debris flow 29 , and earthquakes 30 . Two widely used types of microphones exist, traditional electret condenser and microelectromechanical systems (MEMS)-based microphones.…”

“…Microphones, which convert sound waves to electrical signals, are indispensable in various applications, such as consumer electronics 1-5 , automobiles 6 , hearing aid devices 7,8 , wearable health monitoring 9-19 , photoacousticbased gas sensing [20][21][22][23][24][25] , and the monitoring of natural disasters, such as volcanic eruptions [26][27][28] , debris flow 29 , and earthquakes 30 . Two widely used types of microphones exist, traditional electret condenser and microelectromechanical systems (MEMS)-based microphones.…”