Integrated Piezoelectric AlN Thin Film with SU-8/PDMS Supporting Layer for Flexible Sensor Array.

Hong Goo Yeo,Hongsoo Choi,Jae Eun Jang,Joontaek Jung,Minkyung Sim

doi:10.3390/s20010315

Hong Goo Yeo, Hongsoo Choi + Show 3 more

Open Access

https://doi.org/10.3390/s20010315

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Abstract

This research focuses on the development of a flexible tactile sensor array consisting of aluminum nitride (AlN) based on micro-electro-mechanical system (MEMS) technology. A total of 2304 tactile sensors were integrated into a small area of 2.5 × 2.5 cm2. Five hundred nm thick AlN film with strong c-axis texture was sputtered on Cr/Au/Cr (50/50/5 nm) layers as the sacrificial layer coated on a Si wafer. To achieve device flexibility, polydimethylsiloxane (PDMS) polymer and SU-8 photoresist layer were used as the supporting layers after etching away a release layer. Twenty-five mM (3-mercaptopropyl) trimethoxysilane (MPTMS) improves the adhesion between metal and polymers due to formation of a self-assembled monolayer (SAM) on the surface of the top electrode. The flexible tactile sensor has 8 × 8 channels and each channel has 36 sensor elements with nine SU-8 bump blocks. The tactile sensor array was demonstrated to be flexible by bending 90 degrees. The tactile sensor array was demonstrated to show clear spatial resolution through detecting the distinct electrical response of each channel under local mechanical stimulus.

Highlights

A range of information from the surrounding environment is acquired through sensory mechanisms such as taste, hearing, vision, and touch
We propose a mechanical systems (MEMS) fabrication process for an aluminum nitride (AlN)-based tactile sensor array with poly propose a MEMS fabrication process for an AlN-based tactile sensor array with poly (PDMS) and an SU-8 bump structure, which serves as a contact force (including (PDMS) and an SU-8 bump structure, which serves as a contact force for translation into four piezoelectric transducers (Figure 1)
The mixed PDMS solution was poured on the device and a manual doctor blade method using a square-shaped glass slab was applied to fill the gaps between the 300 μm-thick SU-8 bumps (Figure 2j)

Summary

Introduction

A range of information from the surrounding environment is acquired through sensory mechanisms such as taste, hearing, vision, and touch. Unlike PVDF film, AlN thin films show a wide working films show a wide working temperature range, from −196 to 1150 ◦ C, with a high electromechanical temperature range, from −196 to 1150 °C, with a high electromechanical coupling coefficient due to coupling coefficient due to the low dielectric permittivity and relevant piezoelectric coefficient [29]. Foil substrates to enlarge the field of applications of fabricated AlN sensors [31,32,33,34] It is it is still rarely reported for flexible MEMS tactile sensor array using AlN thin film [35]. Still rarely reported for flexible MEMS tactile sensor array using AlN thin film [35]. After releasing the tactile sensor from the thick AlN thin film was grown by sputtering at room temperature.

Fabrication Process of the Tactile Sensor Array

Fabricated Tactile Sensor Array

Characterization of the Tactile Sensor Array

Hzneighboring was applied channel to the sensor using the aprobe

Findings

Conclusions