Biomimetic Soft Polymer Microstructures and Piezoresistive Graphene MEMS Sensors using Sacrificial Metal 3D Printing

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Abstract

Recent advances in 3D printing technology have enabled unprecedented design freedom across an ever-expanding portfolio of materials. However, direct 3D printing of soft polymeric materials such as PDMS is challenging, especially for structural complexities such as high-aspect ratio (> 20) structures, 3D microfluidic channels (~150 µm diameter), and biomimetic microstructures. This work presents a novel processing method entailing 3D-printing of a thin-walled sacrificial metallic mold, soft polymer casting, and acidic etching of the mold. The proposed workflow enables the facile fabrication of various complex, bioinspired, PDMS structures (e.g. 3D double helical microfluidic channels embedded inside high-aspect ratio pillars) that are difficult or impossible to fabricate using currently available techniques. The microfluidic channels are further infused with conductive graphene nanoplatelets ink to realize two flexible piezoresistive MEMS sensors (a bioinspired flow/tactile sensor and a dome-like force sensor) with embedded sensing elements. The MEMS force sensor is integrated into a Philips 9000 series electric shaver to demonstrate its application in ‘smart’ consumer products in the future. Aided by current trends in industrialization and miniaturization in metal 3D printing, the proposed workflow shows promise as a low-temperature, scalable, and cleanroom-free technique of fabricating complex, soft polymeric, biomimetic structures and embedded MEMS sensors.
Original languageEnglish
Pages (from-to)1094-1104
JournalACS Applied Materials & Interfaces
Volume13
Issue number1
Early online date4-Jan-2021
DOIs
Publication statusPublished - 13-Jan-2021

Keywords

  • 3D printing
  • additive manufacturing
  • MEMS
  • flow sensor
  • pressure sensor
  • embedded sensing
  • graphene
  • piezoresistive
  • bioinspiration
  • microfluidics

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