Design, Fabrication, and Characterization of BESOI-Accelerometer Exploiting Photonic Bandgap Materials

Abstract

This paper reports the numerical and experimental investigation of a bulk and etch silicon on insulator optoelectromechanical system realized using a multilayer metal-dielectric photonic bandgap (PBG) structure. A specific optical structure is designed, which embeds an air gap; the acceleration to be measured induces displacements into a proof mass that in turn are transduced as variations in the optical reflectance spectrum of the PBG stack. The PBG optical stack is made of metals and dielectrics. Because of the large difference in the refractive indexes between these two classes of materials, the resulting optical properties of PBG transparent metals allow for obtaining a sharp change in the output signal even for very small changes of the air gap and therefore of the relative positions of the proof mass. The microelectromechanical system consists of a suspended square-shaped mass supported by four crab-leg beams; the central part is used as active optical area where the light beam is to be focused. The advantages of silicon micromachining combined with PBG properties have been addressed. The sensor proposed has been initially analytically modeled and numerically studied using CoventorWare. Then the device has been fabricated and an extensive experimental campaign has been performed.Index Terms-Bulk and etch silicon on insulator (BESOI) technology, micro-optoelectromechanical systems (MOEMS), photonic bandgap materials.

Hybrid Micro Electro Mechanical Sensor Based on Graphene Oxide/Polyvinyl Alcohol for Humidity Measurements

“…In order to increase the conductivity of the GO/PVA sensor, the sensor was annealed at 300 °C. A natural frequency of ~350 Hz was estimated by using the heterogeneous beam theory [14,15]. In order to validate the readout based on the variation of the natural frequency of the mechanical oscillator as function of the variation of RH, two integrated strain gauges were connected in a Wheatstone bridge and the output was acquired by using an oscilloscope (LeCroywaverunner 6050) as shown in Figure 2.…”

“…The approach here proposed is based on a single device to measure RH by using different readout strategies. It is based on the adoption of a GO/PVA composite [13] used as functional material, and deposited over a BESOI-based microsensor [14,15], operating as mechanical oscillator and designed through MEMSPRO. In the presence of an increment of RH this material is able to increase its inertial mass and, at the same time, it is able to increase its conductivity.…”

Optical MEMS accelerometer sensor relying on a micro‐ring resonator and an elliptical disk

“…Among the various sensing technologies used in the MEMS accelerometers, the capacitive-based accelerometers are the most popular ones, due to their simplicity and straightforward fabrication process; however, these MEMS devices have also shown some drawbacks such as curling effect [16] and parasitic capacitance [17]. A promising method to overcome these disadvantages is to use an optical sensing technology instead [18][19][20][21][22]. In general, these optical motion sensors are more sensitive and have higher resolution compared to capacitive ones [22].…”

Analysis of a Hybrid Micro-Electro-Mechanical Sensor Based on Graphene Oxide/Polyvinyl Alcohol for Humidity Measurements

“…The method pursued here will be based on the adoption of a GO/PVA composite [21] used as a functional material and deposited over a BESOI-based microsensor [22,23] operating as a mechanical oscillator which designed through MEMSPRO (version 2017). In the presence of an increment of RH, this material is able to increase its inertial mass, and at the same time, it is able to increase its conductivity.…”