Capacitive sensing for monitoring of microfluidic protocols using nanoliter dispensing and acoustic mixing

Yaqi Zhang, Muhsincan Sesen, Alex De Marco, Adrian Neild

Research output: Contribution to journalArticleResearchpeer-review

6 Citations (Scopus)


The development of protocols for bio/chemical reaction requires alternate dispensing and mixing steps. While most microfluidic systems use the opening of additional parts of the channel to allow the ingress of fixed volumes of fluid, this requires knowledge of the protocol before the design of the chip. Our approach of using a microfluidic valve to regulate the flow into an initially empty cavity allows for on-chip protocol development and refinement. Mixing is provided by way of surface acoustic wave excitation; this high-frequency vibration causes steady-state streaming flows. We show that capacitive sensing can be used to measure fluid levels, even if multiple fluid types are used, such that nanoliter dispensing accuracy is achieved. Also, the capacitive readout can be used to establish mixing quality and to monitor temperature fluctuations. These capabilities allow for protocols to be conducted without optical assessment and thus will allow for multiplexing, such that reactions could be conducted, simultaneously, in multiple chambers across a chip.

Original languageEnglish
Pages (from-to)10725-10732
Number of pages8
JournalAnalytical Chemistry
Issue number15
Publication statusPublished - 4 Aug 2020

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