PMID- 31853525 OWN - NLM STAT- MEDLINE DCOM- 20210621 LR - 20210621 IS - 1473-0189 (Electronic) IS - 1473-0189 (Linking) VI - 20 IP - 4 DP - 2020 Feb 21 TI - Digital microfluidic meter-on-chip. PG - 722-733 LID - 10.1039/c9lc00989b [doi] AB - The accurate monitoring and control of liquid flow at low flow rates have become increasingly important in contemporary biomedical research and industrial monitoring. Inspired by the drop-counting principle implemented in a clinical gravity drip, we propose a novel microfluidic flowmetry technology for polydimethylsiloxane (PDMS)-based conventional microfluidic devices, known as a microfluidic digital meter-on-chip (DMC), to achieve on-chip and localized microflow measurements with ultrahigh precision and a wide tunable range. The DMC technology primarily relies on capillarity, unlike a gravity drip, to induce a characteristic interfacial droplet pinch-off process, from which digital microflowmetry devices can discretize continuous flow into countable transferred liquid units with consistent quantifiable volumes. Enabled by the passive discretization principle and optical transparency, the DMC device requires no external energy input or bulky control equipment, and a non-contact wireless optical detection scheme using a smartphone can be conveniently used as a readout module. Moreover, the DMC technology achieves an ultrahigh flow-to-frequency sensitivity (6.59 Hz (muL min(-1))(-1)) and resolution (droplet transfer volume down to 2.5 nL, nearly two orders of magnitude smaller than in previously reported work, resulting in ultralow flow rates of 1 muL min(-1)). In addition, the flow rate measurement range covers up to 80 muL min(-1) and down to at least 150 nL min(-1) (over 100 times lower than reported similar digital flowmetry on the same time scale) using the current device configuration. Benefiting from its simple device architecture and adaptability, the versatile DMC technology can be seamlessly integrated with various microfluidic and nanofluidic devices for drug delivery and biochemical analysis, serving as a promising technology platform for next-generation highly demanding microflow measurements. FAU - Fang, Zecong AU - Fang Z AUID- ORCID: 0000-0003-0491-0207 AD - Micro-Nano Innovations (MiNI) Laboratory, Department of Biomedical Engineering, University of California, Davis, CA 95616, USA. tingrui@ ucdavis.edu. FAU - Ding, Yi AU - Ding Y AD - Micro-Nano Innovations (MiNI) Laboratory, Department of Biomedical Engineering, University of California, Davis, CA 95616, USA. tingrui@ ucdavis.edu and Department of Electrical and Computer Engineering, University of California, Davis, CA 95616, USA. FAU - Zhang, Zhichao AU - Zhang Z AD - Micro-Nano Innovations (MiNI) Laboratory, Department of Biomedical Engineering, University of California, Davis, CA 95616, USA. tingrui@ ucdavis.edu. FAU - Wang, Fei AU - Wang F AUID- ORCID: 0000-0003-1871-1022 AD - School of Microelectronics, Southern University of Science and Technology, Shenzhen, 518055, China. FAU - Wang, Zuankai AU - Wang Z AUID- ORCID: 0000-0002-3510-1122 AD - Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, 999077, China. FAU - Wang, Hao AU - Wang H AD - Department of Energy and Resources Engineering, Peking University, Beijing, 100871, China. FAU - Pan, Tingrui AU - Pan T AUID- ORCID: 0000-0002-8851-0667 AD - Micro-Nano Innovations (MiNI) Laboratory, Department of Biomedical Engineering, University of California, Davis, CA 95616, USA. tingrui@ ucdavis.edu and Department of Electrical and Computer Engineering, University of California, Davis, CA 95616, USA. LA - eng GR - P42 ES004699/ES/NIEHS NIH HHS/United States PT - Journal Article PT - Research Support, N.I.H., Extramural PT - Research Support, U.S. Gov't, Non-P.H.S. DEP - 20191219 PL - England TA - Lab Chip JT - Lab on a chip JID - 101128948 SB - IM MH - Lab-On-A-Chip Devices MH - *Microfluidic Analytical Techniques MH - *Microfluidics MH - Rheology MH - Smartphone EDAT- 2019/12/20 06:00 MHDA- 2021/06/22 06:00 CRDT- 2019/12/20 06:00 PHST- 2019/12/20 06:00 [pubmed] PHST- 2021/06/22 06:00 [medline] PHST- 2019/12/20 06:00 [entrez] AID - 10.1039/c9lc00989b [doi] PST - ppublish SO - Lab Chip. 2020 Feb 21;20(4):722-733. doi: 10.1039/c9lc00989b. Epub 2019 Dec 19.