Engineering polymer MEMS using combined microfluidic pervaporation and micro-molding

Damien Thuau,Cédric Ayela,Cédric Laval,Philippe Poulin,Isabelle Dufour,Jean-Baptiste Salmon

doi:10.1038/s41378-018-0017-2

Abstract

In view of the extensive increase of flexible devices and wearable electronics, the development of polymer micro-electro-mechanical systems (MEMS) is becoming more and more important since their potential to meet the multiple needs for sensing applications in flexible electronics is now clearly established. Nevertheless, polymer micromachining for MEMS applications is not yet as mature as its silicon counterpart, and innovative microfabrication techniques are still expected. We show in the present work an emerging and versatile microfabrication method to produce arbitrary organic, spatially resolved multilayer micro-structures, starting from dilute inks, and with possibly a large choice of materials. This approach consists in extending classical microfluidic pervaporation combined with MIcro-Molding In Capillaries. To illustrate the potential of this technique, bilayer polymer double-clamped resonators with integrated piezoresistive readout have been fabricated, characterized, and applied to humidity sensing. The present work opens new opportunities for the conception and integration of polymers in MEMS.

Highlights

Micro-electro-mechanical systems (MEMS) were made of silicon (Si) material for a long time using fabrication technologies derived from the semiconductor integrated circuit industry
The first step consists in the fabrication of a piezoresistive functional layer using microfluidic pervaporation starting from dilute carbon nanotubes (CNTs)-polyvinyl alcohol (PVA) inks, as already reported in ref.[22]
By contrast to conventional microfabrication processes such as micro-molding or photolithography that are limited to UV-curable or heat-curable polymers or thermoplastics[35,36,37,38], microfluidic pervaporation combined with MIcro-Molding In Capillaries (MIMIC) a priori allows the micro-structuration of almost any type of materials starting from dilute colloidal dispersions to polymer solutions

Summary

Introduction

Micro-electro-mechanical systems (MEMS) were made of silicon (Si) material for a long time using fabrication technologies derived from the semiconductor integrated circuit industry. Recent advances in materials science and mechanical engineering have introduced the use of polymers in MEMS devices to meet the increasing needs of future applications[1,2]. Owing to their particular properties (low cost, flexibility, biocompatibility), polymer and composite material-based MEMS have the potential to be a powerful alternative to Si-based MEMS devices for their use in biological applications, mechanical energy harvesting, or for any other application requiring sensing and actuation[3]. While Si-based microfabrication techniques are well established and understood, new processing techniques still need to be developed for engineering organic microscale and nanoscale materials[4].

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