Platinum Micro-Hotplates on Thermal Insulated Structure for Micro-Thermoelectric Gas Sensor

In this paper, we investigate the properties of platinum heater micro-hotplates built on a thin dielectric membrane and used for the catalytic combustion of hydrogen in a micro-thermoelectric hydrogen gas sensor. The response of the micro-hotplates was studied with different working temperatures and a response time below 95 ms was determined at a working temeprature of 350°C. It's shown that the fabricated micro-hotplates can bear temperature as high as 600°C. Temperature measurements were carried out with an infrared camera and show an extremely sharp response of the catalyst to the temperature raise with a response time of less than 1s. The response of the hydrogen gas sensor fabricated with these micro-hotplates is reported at different temperature and for 1 v/v % hydrogen in air. The performance of the gas sensor is also examined with and without a micro-hotplate heat spreader located below the membrane. For a 70-μm-thick heat spreader, the heat dispersion from the membrane is enhanced. However, the hydrogen response of the gas sensor with the heat spreader is reduced 1/3 of the sensor without the heat spreader though the temperature distribution is more uniform below the catalyst.