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.
Original language | English (US) |
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Pages (from-to) | 1191-1197 |
Number of pages | 7 |
Journal | Lab on a Chip |
Volume | 14 |
Issue number | 6 |
DOIs | |
State | Published - Mar 21 2014 |
ASJC Scopus subject areas
- Bioengineering
- Biochemistry
- General Chemistry
- Biomedical Engineering