title: Micromachined electrochemical T-switches for cell sorting applications.
abstract: MEMS micro-T-switches actuated via electrochemical bubbles for cell sorting applications in a monolithic chip level are proposed and successfully demonstrated. The electrolysis-bubble actuator, which has the features of low operation temperature and high surface-tension force, is developed to actuate the micro-T-switch sorting structure in our device. The double T-structure design, the T-shape microchannel with the movable micro-T-switch structure located at the junction of the T-shape microchannel, with the electrolysis-bubble actuator makes an active-binary switch function available for cell sorting applications. The room temperature operation and the low voltage required for electrolysis actuation minimize the possibility of cell-damage that happens in the conventional high electric separation instruments, such as flow cytometry. The function of our micro-T-switch chip with a low required actuation voltage of 3.0 approximately 3.5 V is demonstrated by using human hepatoma cells in this paper. The pH-value measurements characterize the pH-value variation and distribution in the actuating chambers and the mainstream microchannels to trace the possible liver-cell injury due to the pH-value variation during electrolysis-actuation operation. The 84.1% cell viability in the sorted human hepatoma cells through our micro-T-switch sorter is observed via the fluorescence assay technique. Furthermore, 70.2% of total injected cells recover in culture after sorting and grow into colonies after micro-T-switch sorting operation. In this paper, we describe the design, microfabrication, and characterization of our micro-T-switch cell-sorting chip. We also report the cell-sorting demonstration and the cell viability results for the mammalian liver cells through our micro-T-switch cell-sorting chip.
authors.affiliation: Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu, Taiwan 300, R.O.C.
authors.forename: Chen-Ta
authors.initials: CT
authors.lastname: Ho
authors.forename: Ruei-Zeng
authors.initials: RZ
authors.lastname: Lin
authors.forename: Hwan-You
authors.initials: HY
authors.lastname: Chang
authors.forename: Cheng-Hsien
authors.initials: CH
authors.lastname: Liu
mesh_terms: D002460:Cell Line; D002469:Cell Separation / Q000295:instrumentation* / Q000379:methods*; D002470:Cell Survival; D004563:Electrochemistry; D022781:Hepatocytes / Q000166:cytology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods*; D013696:Temperature