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This paper describes the use of a printed circuit technology to generate hydrophilic channels in a filter paper. Patterns of channels were designed using Protel soft, and printed on a blank paper. Then, the patterns were transferred to a sheet copper using a thermal transfer printer. The sheet copper with patterns was dipped into ferric chloride solution to etch the whole patterns of the sheet copper. At last, the etched sheet copper was coated with a film of paraffin and then a filter paper. An electric iron was used to heat the other side of the sheet copper. The melting paraffin penetrated full thickness of the filter paper and formed a hydrophobic “wall”. Colorimetric assays for the presence of protein and glucose were demonstrated using the paper-based device. The work is helpful to researchers to fabricate paper-based microfluidic devices for monitoring health and detecting disease

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A new method for converting a microdroplet on a piezoelectric substrate into continuous fluid flow in microchannels is presented. An interdigital transducer with 27.5 MHz center frequency is fabricated on a 1280 yx-LiNbO3 piezoelectric substrate for exciting surface acoustic wave. A PDMS (Polydimethylsiloxane) microchannel is mounted on the piezoelectric substrate. One end of the microchannel is connected with water absorbing paper, while the other end of the microchannel is in touch with a droplet to be converted. The surface acoustic wave is used for controlling the evaporation velocity of the fluid in the microchannel. Part of fluid in the droplet can be entered into the microchannel and transported there due to the evaporation and capillary effects. Red dye solution is used to demonstrate the conversion of the droplet and the transportation of the fluid in the microchannel. Results show that the droplet on the piezoelectric substrate can successfully be converted into continuous fluid. The flow velocity is increased with the power of the electric signal applied to the interdigital transducer. Average flow velocity is 0.0235μl/s when the power of the electric signal is 30.0dBm. The work is helpful for piezoelectric microfluidic devices for biochemical analysis.