@article{sharma_velev_2015, title={Remote Steering of Self-Propelling Microcircuits by Modulated Electric Field}, volume={25}, ISSN={["1616-3028"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84941021865&partnerID=MN8TOARS}, DOI={10.1002/adfm.201502129}, abstractNote={The principles and design of “active” self‐propelling particles that can convert energy, move directionally on their own, and perform a certain function is an emerging multidisciplinary research field, with high potential for future technologies. A simple and effective technique is presented for on‐demand steering of self‐propelling microdiodes that move electroosmotically on water surface, while supplied with energy by an external alternating (AC) field. It is demonstrated how one can control remotely the direction of diode locomotion by electronically modifying the applied AC signal. The swimming diodes change their direction of motion when a wave asymmetry (equivalent to a DC offset) is introduced into the signal. The data analysis shows that the ability to control and reverse the direction of motion is a result of the electrostatic torque between the asymmetrically polarized diodes and the ionic charges redistributed in the vessel. This novel principle of electrical signal‐coded steering of active functional devices, such as diodes and microcircuits, can find applications in motile sensors, MEMs, and microrobotics.}, number={34}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Sharma, Rachita and Velev, Orlin D.}, year={2015}, month={Sep}, pages={5512–5519} }
 @article{sharma_blackburn_hu_wiltberger_velev_2014, title={On-chip microelectrode impedance analysis of mammalian cell viability during biomanufacturing}, volume={8}, ISSN={["1932-1058"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84907202365&partnerID=MN8TOARS}, DOI={10.1063/1.4895564}, abstractNote={The characterization of cell viability is a challenging task in applied biotechnology, as no clear definition of cell death exists. Cell death is accompanied with a change in the electrical properties of the membrane as well as the cell interior. Therefore, changes in the physiology of cells can be characterized by monitoring of their dielectric properties. We correlated the dielectric properties of industrially used mammalian cells, sedimented over interdigitated microelectrodes, to the AC signal response across the chip. The voltage waveforms across the electrodes were processed to obtain the circuit impedance, which was used to quantify the changes in cell viability. We observed an initial decrease in impedance, after which it remained nearly constant. The results were compared with data from the dye exclusion viability test, the cell specific oxygen uptake rate, and the online viable cell density data from capacitance probes. The microelectrode technique was found to be sensitive to physiological changes taking place inside the cells before their membrane integrity is compromised. Such accurate determination of the metabolic status during this initial period, which turned out to be less well captured in the dye exclusion tests, may be essential for several biotechnology operations.}, number={5}, journal={BIOMICROFLUIDICS}, author={Sharma, Rachita and Blackburn, Tobias and Hu, Weiwei and Wiltberger, Kelly and Velev, Orlin D.}, year={2014}, month={Sep} }