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Issue 6, 2014
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Real-time feedback control of pH within microfluidics using integrated sensing and actuation

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Abstract

We demonstrate a microfluidic system which applies engineering feedback principles to control the pH of a solution with a high degree of precision. The system utilizes an extended-gate ion-sensitive field-effect transistor (ISFET) along with an integrated pseudo-reference electrode to monitor pH values within a microfluidic reaction chamber. The monitored reaction chamber has an approximate volume of 90 nL. The pH value is controlled by adjusting the flow through two input channels using a pulse-width modulated signal applied to on-chip integrated valves. We demonstrate real-time control of pH through the feedback-controlled stepping of 0.14 pH increments in both the increasing and decreasing direction. The system converges to the pH setpoint within approximately 20 seconds of a step change. The integration of feedback theory into a microfluidic environment is a necessary step for achieving complete control over the microenvironment.

Graphical abstract: Real-time feedback control of pH within microfluidics using integrated sensing and actuation

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Article information


Submitted
24 Oct 2013
Accepted
23 Jan 2014
First published
23 Jan 2014

Lab Chip, 2014,14, 1191-1197
Article type
Paper

Real-time feedback control of pH within microfluidics using integrated sensing and actuation

D. Welch and J. B. Christen, Lab Chip, 2014, 14, 1191
DOI: 10.1039/C3LC51205C

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