@article{ma_zhang_chang_velev_wiltberger_kshirsagar_2019, title={Real-time monitoring and control of CHO cell apoptosis by in situ multifrequency scanning dielectric spectroscopy}, volume={80}, ISSN={["1873-3298"]}, DOI={10.1016/j.procbio.2019.02.017}, abstractNote={• Detected apoptosis in CHO cells with in situ scanning dielectric spectroscopy. • Demonstrated potential to recover from early apoptosis in a real CHO cell process. • Applied scanning dielectric spectroscopy to detect deviation in manufacturing batch. Process control strategies based on the physiological status of cells have recently been used to enhance mammalian cell culture productivity and robustness. In this study, we investigated the feasibility of using full-spectrum dielectric spectroscopy for detecting shifts in cell physiology and as a feedback tool to increase process efficiency. Multi-frequency permittivity spectra were collected from cell culture processes in which apoptosis was induced by glucose depletion, nutrient depletion, or chemical treatment. Meanwhile, key parameters of critical frequency ( f c ) and Cole-Cole alpha (α) were calculated in real time from the β-dispersion curve and correlated to data from off-line viability measurements. Results show that physiological changes in apoptotic cells were reflected in the on-line parameters earlier than from off-line methods. Using information from the on-line parameters, we achieved partial or full recovery from early apoptosis by replenishing the depleted feed. We also demonstrate that by using trends in f c , we could detect a deviation in media preparation in a manufacturing process which could not be achieved using conventional measurements. The results demonstrate that full-spectrum dielectric spectroscopy can be used as a facile tool for early detection of physiological changes and process adjustment in real-time to enhance bioreactor process productivity and robustness.}, journal={PROCESS BIOCHEMISTRY}, author={Ma, Fuduo and Zhang, An and Chang, David and Velev, Orlin D. and Wiltberger, Kelly and Kshirsagar, Rashmi}, year={2019}, month={May}, pages={138–145} }
 @article{shields_han_ma_miloh_yossifon_velev_2018, title={Supercolloidal Spinners: Complex Active Particles for Electrically Powered and Switchable Rotation}, volume={28}, ISSN={["1616-3028"]}, DOI={10.1002/adfm.201803465}, abstractNote={AbstractA class of supercolloidal particles that controllably spin about their central axis in AC electric fields is reported. The rational design of these “microspinners” enables their rotation in a switchable manner, which gives rise to several interesting and programmable behaviors. It is shown that due to their complex shape and discrete metallic patches on their surfaces, these microspinners convert electrical energy into active motion via the interplay of four mechanisms at different electric field frequency ranges. These mechanisms of rotation include (in order of increasing frequency): electrohydrodynamic flows, reversed electrohydrodynamic flows, induced charge electrophoresis, and self‐dielectrophoresis. As the primary mechanism powering their motion transitions from one phenomenon to the next, these microspinners display three directional spin inversions (i.e., from clockwise to anticlockwise, or vice versa). To understand the mechanisms involved, this experimental study is coupled with scaling analyses. Due to their frequency‐switchable rotation, these microspinners have potential for applications such as interlocking gears in colloidal micromachines. Moreover, the principles used to power their switchable motion can be extended to design other types of supercolloidal particles that harvest electrical energy for motion via multiple electrokinetic mechanisms.}, number={35}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Shields, Charles Wyatt and Han, Koohee and Ma, Fuduo and Miloh, Touvia and Yossifon, Gilad and Velev, Orlin D.}, year={2018}, month={Aug} }
 @article{heatley_ma_wu_2017, title={Colloidal molecules assembled from binary spheres under an AC electric field}, volume={13}, number={2}, journal={Soft Matter}, author={Heatley, K. L. and Ma, F. D. and Wu, N.}, year={2017}, pages={436–444} }