Microsystem Technologies

, Volume 19, Issue 7, pp 989–994 | Cite as

A micro PDMS flow sensor based on time-of-flight measurement for conductive liquid

  • Haixia Yu
  • Dachao LiEmail author
  • Robert C. Roberts
  • Kexin Xu
  • Norman C. Tien
Technical Paper


Transdermal extraction of interstitial fluid (ISF) offers an attractive method for non-invasive blood glucose monitoring. In order to calculate blood glucose concentration accurately, precise volume measurement of transdermally extracted ISF is required due to human skin’s varying permeability. In this paper, we presented a novel flow sensor fabricated from polydimethylsiloxane (PDMS), designed to measure the volume of conductive liquid. The flow sensor consists of two pairs of metal electrodes, which are fabricated in the PDMS channel. The volume of liquid is measured utilizing the time-of-flight of the two electrode pairs’ resistance while the liquid is flowing through the flow sensor. 1–14 μL normal saline solution was measured, the flow sensor measured volumes correlate very well (R 2 = 0.9996 and R 2 = 0.9975 for vacuum pump and syringe pump situations respectively) with the actual volumes. And the coefficient of variation for 10 times 10 μL normal saline solution measurement is 0.0077 (vacuum pump) and 0.0381 (syringe pump), respectively. The demonstrated flow sensor provides excellent functionality for conductive liquid.


PDMS Syringe Pump Microfluidic Channel Electrode Pair Flow Sensor 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



This work is supported by the National Natural Science Foundation of China (No. 30800239 and No. 61176107), the Key Projects in the Science and Technology Pillar Program of Tianjin (No. 11ZCKFSY01500), the National Key Projects in Non-profit Industry (No. GYHY200906037), and the Innovation Foundation of Tianjin University.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Haixia Yu
    • 1
    • 2
  • Dachao Li
    • 1
    Email author
  • Robert C. Roberts
    • 2
  • Kexin Xu
    • 1
  • Norman C. Tien
    • 2
  1. 1.State Key Laboratory of Precision Measuring Technology and InstrumentsTianjin UniversityTianjinChina
  2. 2.Department of Electrical Engineering and Computer ScienceCase Western Reserve UniversityClevelandUSA

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