Development of Micro-Heaters with Optimized Temperature Compensation Design for Gas Sensors

Abstract

One of the key components of a chemical gas sensor is a MEMS micro-heater. Micro-heaters are used in both semiconductor gas sensors and NDIR gas sensors; however they each require different heat dissipation characteristics. For the semiconductor gas sensors, a uniform temperature is required over a wide area of the heater. On the other hand, for the NDIR gas sensor, the micro-heater needs high levels of infrared radiation in order to increase sensitivity. In this study, a novel design of a poly-Si micro-heater is proposed to improve the uniformity of heat dissipation on the heating plate. Temperature uniformity of the micro-heater is achieved by compensating for the variation in power consumption around the perimeter of the heater. With the power compensated design, the uniform heating area is increased by 2.5 times and the average temperature goes up by 40 °C. Therefore, this power compensated micro-heater design is suitable for a semiconductor gas sensor. Meanwhile, the poly-Si micro-heater without compensation shows a higher level of infrared radiation under equal power consumption conditions. This indicates that the micro-heater without compensation is more suitable for a NDIR gas sensor. Furthermore, the micro-heater shows a short response time of less than 20ms, indicating a very high efficiency of pulse driving.

Experimental investigation and numerical modeling of the thermal behavior of a micro-heater

“…Some of them are based on the use of micro-machined silicon hotplate coated with a sensitive metal that oxides in the presence of the gas to be detected. A variation of its resistance reveals the presence of the target gas (Dong et al 2011;Hwang et al 2011). Some of these detectors developed to the control of emissions during combustion process must work on a high range of temperature (Hwang et al 2011;Sharma and Khanna 2013).…”

Development of microheaters for gas sensor with an AT-Mega 8535 temperature controller using a PWM (pulse width modulation) method

“…The performance of the control system also determine the quality of a gas sensor [3]. Therefore, the objective of the current investigation is development of simple Cu microheater and a temperature control device with AT-Mega 8535 using pulse width modulation (PWM) method.…”

“…Microheater in a gas sensor is a small resistive heater operate at controlled temperature between 200-500 o C which depends on the active or sensitive layers applied in the sensor [2,3]. Microheater required a very low power and short time response to reach its temperature setting values [3]. Many researchers successfully developed a microheater thin film using poly-Si, NiCr and Pt/Ti [4].…”

“…The gas sensor is an example of chemical sensor applied for particles detector in air quality or pollution monitoring such as oxygen and carbon monoxide content. Microheater in a gas sensor is a small resistive heater operate at controlled temperature between 200-500 o C which depends on the active or sensitive layers applied in the sensor [2,3]. Microheater required a very low power and short time response to reach its temperature setting values [3].…”

Observation of convection phenomenon by high-performance transparent heater based on Pt-decorated Ni micromesh

“…1,2 In general, the heaters in such sensors are the main technical factors for enhancing the selectivity, sensitivity, and response and recovery speeds of the sensors, or the adsorption and desorption the target materials (gas or PM). 1,2,[16][17][18][19] In this study, a high-performance transparent heater based on Pt-decorated Ni micromesh was fabricated by a combination of transfer printing process and Pt sputtering. 11,20 The resulting Ni micromesh-based heater with Pt decoration exhibited excellent mechanical durability, such as adhesion to substrates and flexibility, and heat-generating performance.…”