Optical-Interferometry-Based CMOS-MEMS Sensor Transduced by Stress-Induced Nanomechanical Deflection

Area of Science:

• * Sensor Technology
• * Chemical Sensing
• * Optoelectronics

Background:

• * Traditional chemical sensors often face limitations in sensitivity and response time.
• * Integrating optical interferometry with electronic circuits offers a promising avenue for enhanced sensing capabilities.

Purpose of the Study:

• * To develop a novel Fabry-Perot interferometer sensor combined with a metal-oxide-semiconductor field-effect transistor (MOSFET) circuit.
• * To demonstrate a new signal transduction method for chemical sensing applications.
• * To achieve high-efficiency transduction of small physical changes into electrical signals.

Main Methods:

• * Fabrication of a Fabry-Perot interferometer sensor utilizing a polychloro-para-xylylene membrane (350 nm thick, 100 µm diameter) with a 300 nm air gap.
• * Integration of a metal-oxide-semiconductor field-effect transistor (MOSFET) source follower circuit for photocurrent processing.
• * Three-step signal transduction: mechanical deflection, transmittance change, and photocurrent change.

Main Results:

• * Achieved linearity in the integrated source follower circuit's output.
• * Demonstrated successful gas detection of 80-ppm ethanol.
• * Observed a measurable output voltage change corresponding to a small membrane deformation of 50 nm.

Conclusions:

• * The developed sensor system effectively integrates optical and electronic components for chemical sensing.
• * The novel transduction technique enables sensitive detection of analytes through minute physical deformations.
• * The high-efficiency transduction mechanism holds potential for advanced chemical sensing devices.