An Inkjet Printing Technique for Scalable Microfabrication of Graphene-Based Sensor Components

Yu-Min Fu,Che-Hao Kang,Meng-Chuin Chou,Mark C Hersam,Guan-Yu Chen,Yu-Ting Cheng,Ethan B Secor,Pu-Wei Wu

doi:10.1109/access.2020.2990501

Abstract

This paper presents a versatile and precise graphene patterning technique using the combined process of masking and inkjet printing. A graphene-based structure is fabricated by first defining the structural pattern and position using a masking mold, which can be either electroplated copper or deep reactive ion etching (DRIE) silicon shadow mask, followed by inkjet deposition of graphene ink and lift-off. The hybrid technique can realize high-fidelity, high-resolution graphene-based microstructures including free-standing and cantilever beams, four-point resistive measurement structures, and piezoresistive sensing elements with a minimum line width of $\sim 20~\mu \text{m}$ . Moreover, this method can facilitate the micropatterning of graphene oxide (GO) and reduced graphene oxide (rGO) on substrates such as polydimethylsiloxane (PDMS) and SiO2/Si for selective cell culturing applications. Owing to the characteristics of low chemical usage, low process temperature and complexity, and high flexibility and fault tolerance of inkjet printing, this technique demonstrates compelling potential for a variety of biomedical applications.

Highlights

Graphene, a two-dimensional honeycomb lattice of carbon atoms offering exceptional electrical, thermal, and mechanical properties such as high carrier mobility [1], thermal conductivity [2], and Young’s modulus [3], has sparked considerable research interest in graphene-based microstructure fabrication for various applications
Leveraging the process versatility, an inkjet-printed back-to-back linked graphene tactile sensor concept has been demonstrated with the capability to differentiate tissue hardness, offering strong potential for practical clinical application in endosurgical palpation
Polydimethylsiloxane (PDMS) is a common structural material in many organ-on-a-chip microfluidic devices owing to the unique characteristics of high permeability for gases and small molecules, optical transparency, and mechanical flexibility for cell culturing

Summary

INTRODUCTION

A two-dimensional honeycomb lattice of carbon atoms offering exceptional electrical, thermal, and mechanical properties such as high carrier mobility [1], thermal conductivity [2], and Young’s modulus [3], has sparked considerable research interest in graphene-based microstructure fabrication for various applications. Li et al [6] employed a chemical vapor deposition (CVD) technique to grow a large-area graphene film, which can be transferred to arbitrary substrates from the initial copper This process facilitated the fabrication of dual-gated field-effect transistors with an electron mobility as high as 4050 cm2 ·V−1 ·s−1 on a SiO2/Si substrates at room temperature. Better process control capabilities including accurate positioning, good spatial resolution, low processing temperature, and thick film deposition by multiple printing passes have shown the greatest potential for microelectronics integration and microelectromechanical systems (MEMS) fabrication. Given these advantages, a number of studies have explored inkjet printing of graphene-based inks for functional devices. The proposed printing process overcomes limitations in line resolution for direct inkjet printing of graphene and improves process tolerance to mitigate nozzle clogging for fine feature printing [16]

EXPERIMENTAL METHODS

DOUBLY-CLAMPED GRAPHENE BEAM FOR PIEZORESISTIVE CHARACTERIZATION

CONCLUSION