A simple poly(dimethylsiloxane) electrophoresis microchip with an integrated contactless conductivity detector

摘要

A simple poly(dimethylsiloxane) (PDMS) microchip was fabricated with an integrated contactless conductivity detector. This microchip consists of a PDMS cover sheet with embedded channels and a glass substrate holding the electrodes. The electrodes are insulated from the microchannel by a PDMS membrane. n-Dodecyl β-D-maltoside was utilized to modify the channel surface to improve its hydrophilicity and to reduce the strong absorption of PDMS. A readout system based on a multiplier was set up for detection, and a commonly used rectifier circuit was added to this system for direct comparison. A mixture of inorganic cations (K+, Na+, Li+) was successfully separated in 100 × 30 μm microchannels and detected by applying a sinusoidal wave with a frequency of 100 kHz and 6 V_p-p. This microchip system was characterized in terms of sensitivity, reproducibility and linearity. It is suitable for mass production due to its robustness, high reproducibility, ease of fabrication and low cost. This work provides a valuable contribution to the realization of low-noise and high-sensitivity portable devices applicable to food and environmental detection fields.