A capillary system with thermal-bubble-actuated 1/spl times/N microfluidic switches via time-sequence power control for continuous liquid handling

A novel thermal-bubble-actuated 1/spl times/N microfluidic switch without the need of external pumps has been successfully fabricated using micromachining process and demonstrated. This device is a valveless switch by means of the triggering thermal-bubble-actuator, the capillary force, the design of the distributed hydrophobic patches in the microchannels, and the time-sequence power control. The switch mechanism among different microchannels in our device is dominated by controlling the format and timing of power input that generates actuating thermal bubbles. The experimental results successfully and robustly demonstrate the switch function of our microcapillary systems to switch continuous liquid into desired outlet ports based on our hydrophobic-patch design and programmable time-sequence bubble actuation. In this paper, we describe the theory, design, synthesis, micromachining process, control circuitry, and its time-sequence control, as well as the experimental demonstration of this microcapillary system.