High-Yield Production of Aqueous Graphene for Electrohydrodynamic Drop-on-Demand Printing of Biocompatible Conductive Patterns.

Amir Ehsan Niaraki Asli,Reza Montazami,Jingshuai Guo,Nicole N Hashemi,Pei Lun Lai

doi:10.3390/bios10010006

Abstract

Presented here is a scalable and aqueous phase exfoliation of graphite to high yield and quality of few layer graphene (FLG) using Bovine Serum Albomine (BSA) and wet ball milling. The produced graphene ink is tailored for printable and flexible electronics, having shown promising results in terms of electrical conductivity and temporal stability. Shear force generated by steel balls which resulted in 2–3 layer defect-free graphene platelets with an average size of hundreds of nm, and with a concentration of about 5.1 mg/mL characterized by Raman spectroscopy, atomic force microscopy (AFM), transmittance electron microscopy (TEM) and UV-vis spectroscopy. Further, a conductive ink was prepared and printed on flexible substrate (Polyimide) with controlled resolution. Scanning electron microscopy (SEM) and Profilometry revealed the effect of thermal annealing on the prints to concede consistent morphological characteristics. The resulted sheet resistance was measured to be for prints as long as 100 mm. Printable inks were produced in volumes ranging from 20 mL to 1 L, with potential to facilitate large scale production of graphene for applications in biosensors, as well as flexible and printable electronics.

Highlights

Printable electronics have received increasing attention due to their broad applications, such as roll-to-roll (R2R) printed solar cells [1], micro electrode array (MEA) [2], biomedical/chemical sensors [3]and the manufacturing of various flexible electronics [4,5,6]
The production of defect-free and stable graphene dispersion in aqueous medium is vastly desired for biological applications
Applying conductive graphene patterns on flexible substrates can aid the electrophysiological study on neuronal cells by resolving the reported mechanical mismatch between biosensors and the soft cell membrane

Summary

Introduction

Printable electronics have received increasing attention due to their broad applications, such as roll-to-roll (R2R) printed solar cells [1], micro electrode array (MEA) [2], biomedical/chemical sensors [3]and the manufacturing of various flexible electronics [4,5,6]. As the printable inks are core components in this field of research, several studies have been conducted on increasing the conductivity and printability of these materials. Indium Tin Oxide (ITO) are the most common conductive inks. The natural brittleness of these materials (e.g., ITO) hinders their applicability to the flexible substrate [10]. In biological sensing applications, utilizing these materials alters the cell shape, organization and function of the cell culture, establishing a reliable communication remains a challenge due to this mechanical mismatch [2]. Researchers have synthesized graphene by the oxidation of graphite through the modified Hummer’s method, chemical vapor deposition (CVD) from hydrocarbon gas and liquid-phase exfoliation [14,15,16,17,18]

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