Design of MEMS Based Microheater for Efficient Gas Sensor

Abstract

A sensor, originates from the Latin word “SENTIRE”, is a device, which perceives and responds to a physical and chemical stimulus. Semiconductor sensors are such type of electronic devices in which the semiconducting material is responsible for sensing function. Micro-Electromechanical Systems (MEMS) based integrated gas sensors present several advantages for these applications such as array fabrication, small size, and unique thermal manipulation capabilities. MEMS based gas sensors, which are usually produced using a standard CMOS (Complementary Metal Oxide Semiconductor) process, have the additional advantages of being readily realized by commercial foundries and amenable to the inclusion of on-chip electronics. Gases are linked to life and their odors tremendously influence the image of our environment. The human nose serves as a highly advanced sensing instrument which is able to differentiate between hundreds of smells but fails if absolute gas concentrations or odorless gases need to be detected. The demand for gas sensing devices which support the human nose is accordingly large. Support is desired in safety applications where combustible or toxic gases are present and in comfort applications, such as climate controls of buildings and vehicles where good air quality is required. Additionally, gas monitoring is needed in process control and laboratory analytics. Most of the microheaters which are used to elevate the temperature of gas sensor, integrated with the design of either platinum, nichrome or poly-silicon etc. as heater element are suitable for high temperatures and were fabricated with poly-silicon as heater material as well as electrode to observe the particular ambient temperature. In the present work, a platinum based coplanar microheater is designed and studied for gas sensing applications. Microheaters with different structures are designed to obtain better temperature uniformity. Interdigitated electrodes can be placed on the same layer as of microheater to obtain a coplanar design. The design has been accomplished using finite element method (FEM) through COMSOL Multiphysics.