We present a new electrochemically-actuated microvalve that does not require an external power source and is well-suited for autonomous stand-alone microfluidic systems. The microvalve is composed of a single bi-metallic Zn/Pt electrode, where the Pt region of the electrode is located in a solution microchannel and the Zn/Pt region of the electrode is located in a separated control microchannel. The Pt electrode is covered with a hydrophobic self-assembled monolayer (SAM) that stops solution flow in the solution microchannel, hence is normally-closed. The microvalve is opened by introducing an electrolyte into the control microchannel, which oxidizes the Zn layer of the Zn/Pt electrode and forces a negative mixed potential of the entire electrode. The negative mixed potential is sufficient to remove the SAM from the Pt electrode through reductive desorption, thus opening the microvalve and allowing the solution to flow. Microvalves based on this actuation mechanism can be used to initiate solution flow in any arbitrary microchannel configuration and significantly simplify peripheral equipment requirements.
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