The Design and Analysis of a Novel Micro Force Sensor Based on Depletion Type Movable Gate Field Effect Transistor

Abstract

A novel micro force sensor based on depletion type vertically movable gate array field effect transistor (VMGAFET) was developed with cross-axis decoupling structure and eight gate arrays. This novel sensor is able to detect ultra-low force and exhibit high measuring sensitivity. An accurate electrical model was then proposed and compared with a long channel model, which is better adopted in small-sized devices to predict the electrical performance of this sensor. We also developed a mechanical model for the micro force sensor. Finite element method simulations were conducted, and the results were in accordance with the theoretical ones. Then, a feasible fabrication process was illustrated for the proposed sensor. The measuring sensitivity and nonlinearity of the micro force sensor with the proposed structure and dimension parameters are $12.528~\mu \text{A}$ /nN and <1.35%, respectively. These theoretical analyses provide insights into the design of depletion type VMAGFET-based sensor and other kinds of devices based on movable gate field effect transistor or with similar movable structures.