Electrochemical control of pH in nano-liter volumes

Auteurs

D. Balakrishnan, G. Lamblin, J.-S. Thomann, A. van den Berg, W. Olthuis, and C. Pascual Garcia

Référence

Nano Letters, vol. 18, no. 5, pp. 2807-2815, 2018

Description

The electrochemical management of the proton concentration in miniaturised dimensions opens the way to control and parallelise multi-step chemical reactions but still it faces many challenges linked to the efficient proton generation and control of their diffusion. Here we present a device operated electrochemically that demonstrates the control of the pH in a cell of ~ 140 nL. The device comprises a microfluidic reactor integrated with a hydraulic mechanism that allows the exchange of reagents and the isolation of protons to decrease the effect of their diffusion. We monitored the pH with a fluorescence marker and calculated the final value from the redox currents. We demonstrate a large pH amplitude control from neutral pH’s beyond the fluorescence marker range at pH 5. Based on the calculations from the faradaic currents, the minimum pH reached should undergo pH ~ 0.9. The pH contrast between neutral and acid pH cells can be maintained during periods longer than 15 minutes with an appropriate design of a diffusion barrier. 

Lien

doi:10.1021/acs.nanolett.7b05054