Fabrication of a microchannel integrated with inner sensors and the analysis of its laminar flow characteristics

Abstract

A rectangular straight microchannel was fabricated with dimensions of 57 mum (H) x 200 mum (W) x 48,050 mum (L), in which the resistance temperature detectors (RTDs) were integrated on the inner surface of the channel wall to measure the temperatures of the fluid more accurately. Platinum (Pt) was used as RTD material. The values of the temperature coefficient of resistance (TCR) of the fabricated Pt-RTDs without annealing ranged about 2800-2900 ppm/degreesC and the variation of the TCR values in the range of 0-110 degreesC was less than 2%. A microheater was also installed at the outlet/inlet of the channel to generate the heat flux. Effects of the temperature-dependent properties on the laminar flow characteristics in the microchannel were investigated experimentally using the fabricated microchannel device. DI water was used as the working fluid. The pressure drop was measured as the mass flow rate and the applied heating power were increased. The microparticle image velocimetry (micro-PIV) was used to measure the detailed velocity fields along the microchannel having various wall temperatures. The pressure drop and micro-PIV measurements revealed that the variation of the fluid properties along the microchannel has a significant effect on the flow resistance but not a considerable effect on the velocity profile. Also, the measured flow resistance and velocity field showed a high degree of consistency with those estimated by the macro-laminar flow theory under our experimental conditions. The proposed microchannel device is expected to be useful in the field of microfluidics. (C) 2002 Elsevier Science B.V. All rights reserved.