Abstract
Microfluidic impedance cytometry (MIC) provides a fast and label-free method for single cell detection and classification. However, the cost and complexity of MIC electrode fabrication limits its implementation in disposable devices for point-of-care (PoC) applications. To address this, we demonstrate the fabrication and characterisation of Field‘s metal (FM) ‘in-contact’ coplanar (icFM) microelectrodes in multilayer elastomer devices and characterise them for microfluidic impedance cytometry. These microelectrodes are fabricated by suction driven molten alloy flow into precast microchannels. After solidification, this electrode layer is bonded to other flow microchannel layer(s) to integrate fluidic operations. Our approach bypasses the conventional clean-room intensive microelectrode fabrication processes and requires a single photolithography step. In a feedback controlled suction-flow MIC setup, our icFM microelectrodes displayed comparable performance to the platinum electrodes in the detection of single human erythrocytes and water-in-oil droplets. Additionally, our microelectrodes can detect single cells entrapped in water-in-oil droplets, an integral operation in droplet based single cell analysis. Thus, fusible alloy microelectrodes provide a facile and cost-effective alternative for impedance flow cytometry.
