Natural-rubber-based flexible microfluidic device

Abstract

The fabrication of flexible devices is of great interest owing to their eco-friendliness, economic prospects, feasibility, and wide range of applications in biocompatible diagnostic devices and flexible labs-on-chips. Therefore, this paper reports a new method developed to fabricate natural-rubber-based microfluidic devices (NRMDs) for optical and electrochemical applications. Furthermore, we provide a detailed protocol that will allow further study using NRMDs for the development of different lab-on-a-chip platforms. Microchannels were successfully replicated in NRMDs through casting of latex collected from trees of Hevea Brasiliensis into an acrylic moulding template. NRMDs combined both flexibility and transparency, the latter of which is an important characteristic for application in spectroscopic measurements in the visible range. When two flexible carbon fiber (FCF) electrodes were inserted into the NRMD, the device stated to work as a flexible electrochemical microcell. FCF electrodes showed a fast response to reach the stationary current immediately after the [Fe(CN)₆]^4−/3− concentration was changed. High reversibility in the cleaning process was also confirmed when the microdevice was cleaned several times. Electronic spectroscopy was used to evaluate the absorption band of potassium ferricyanide and results showed that NRMD is very efficient for spectroscopic analysis in flow. NRMDs with different formats and configurations were evaluated. The findings show that natural rubber is a robust and versatile promising material for building microfluidic labs-on-chips.