Integration of Low-Power Microfluidic Pumps with Biosensors within a Laboratory-on-a-Chip Device Gerald Blanco-Gomez, † Andrew Glidle, † Leonard M. Flendrig, ‡ and Jon M. Cooper* ,† Department of Electronics and Electrical Engineering, University of Glasgow, Glasgow G12 8LT, U.K., and Unilever R&D Vlaardingen, Dept. FSD, Vlaardingen 3130AC, Netherlands We describe the fabrication of a controllable microfluidic valve coupled with an electrochemical pump, which has been designed to deliver reagents to an integrated micro- fluidic biosensing system. Fluid, retained within an inser- tion reservoir using a stop valve, was pumped using electrochemical actuation, providing a low power, low voltage integrated Laboratory-on-a-Chip for reproducible, small volume fluidic manipulation. The properties of the valve were characterized using both X-ray photoelectron spectroscopy and contact angle measurements, enabling the calculation of the magnitude of the forces involved (which were subsequently verified through experimental measurement). Electrochemical generation of oxygen and hydrogen acted as an on-demand pressure system to force fluid over the stop valve barrier. The process of filling-up the biosensing chamber was characterized in terms of the time to fill, the energy used, and the peak power con- sumed. The potential of the device was illustrated using a glucose biosensor. It is anticipated that autonomous microfluidic biological sensing systems will find diverse applications in a variety of remote sensing opportunities, including those for astrobiology, ecological mea- surements under the sea or in the arctic, 1 or within the medical field, in Laboratory-on-a-pill 2 formats for in situ gastro-intestinal monitoring or intra-ocular drug delivery. 3 In such devices, it will be necessary to implement low voltage-low power actuation of fluid flow, to enable simple analytical protocols. In situ microfluidic pumping will enable a series of analytical proposals, including reagent delivery and sensor calibration. In more advanced bio- sensing systems, based, for example, on heterogeneous immu- noassays such as the ELISA, the technology may also prove important in the implementation of one or more separation steps (e.g., in the removal of unbound, labeled antibodies in a hetero- geneous immunosensor). Here, we report on an integrated valve, sensor, and pump to enable a model analytical measurement, based upon the imple- mentation of a glucose microbiosensor. The valve was comprised of a photolithographically patterned hydrophobic barrier 4,5 in a microfluidic channel that controlled the flow of analyte, leading to an electrochemical detection sensor system. The microfluidic pumping unit was enabled through the local electrolysis of water to generate hydrogen and oxygen gas, and so provide the pressure driven flow 6-14 necessary to overcome the hydrophobic barrier, according to the following reactions: 2H 2 O + 2e - T H 2 + 2OH - at - 0.83 V versus Normal Hydrogen Electrode (NHE) at 298 K O 2 + 4e - + 4H + T 2H 2 O at 1.23 V versus NHE at 298 K The relation between the gas volume generated (creating pressure driven flow) and the charge passed was expressed as V H 2 ) V m Q/2F, V O 2 ) V m Q/4F, where F is the Faraday constant, Q is the charge passed through the electrodes, and V m is standard molar volume. The future potential applications of such integrated sensory devices provide constraints on both the valve and the pump. For example, we considered the need for a passive valve, whose mechanism could be electronically triggered by the user (e.g., by a wireless signal). 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