Portable dielectrophoresis for biology:ADEPT facilitates cell trapping,separation,and interactions

Dielectrophoresis is a powerful and well-established technique that allows label-free,non-invasive manipulation of cells and particles by leveraging their electrical properties.The practical implementation of the associated electronics and user interface in a biology laboratory,however,requires an engineering background,thus hindering the broader adoption of the technique.In order to address these challenges and to bridge the gap between biologists and the engineering skills required for the implementation of DEP platforms,we report here a custom-built,compact,universal electronic platform termed ADEPT(adaptable dielectrophoresis embedded platform tool)for use with a simple microfluidic chip containing six microelectrodes.The versatility of the open-source platform is ensured by a custom-developed graphical user interface that permits simple reconfiguration of the control signals to address a wide-range of specific applications:(i)precision positioning of the single bacterium/cell/particle in the micrometer range;(ii)viability-based separation by achieving a 94%efficiency in separating live and dead yeast;(iii)phenotype-based separation by achieving a 96%efficiency in separating yeast and Bacillus subtilis;(iv)cell–cell interactions by steering a phagocytosis process where a granulocyte engulfs E.coli RGB-S bacterium.Together,the set of experiments and the platform form a complete basis for a wide range of possible applications addressing various biological questions exploiting the plug-and-play design and the intuitive GUI of ADEPT.

Glassy carbon microelectrodes minimize induced voltages,mechanical vibrations,and artifacts in magnetic resonance imaging

The recent introduction of glassy carbon(GC)microstructures supported on flexible polymeric substrates has motivated the adoption of GC in a variety of implantable and wearable devices.Neural probes such as electrocorticography and penetrating shanks with GC microelectrode arrays used for neural signal recording and electrical stimulation are among the first beneficiaries of this technology.With the expected proliferation of these neural probes and potential clinical adoption,the magnetic resonance imaging(MRI)compatibility of GC microstructures needs to be established to help validate this potential in clinical settings.Here,we present GC microelectrodes and microstructures—fabricated through the carbon micro-electro-mechanical systems process and supported on flexible polymeric substrates—and carry out experimental measurements of induced vibrations,eddy currents,and artifacts.Through induced vibration,induced voltage,and MRI experiments and finite element modeling,we compared the performances of these GC microelectrodes against those of conventional thin-film platinum(Pt)microelectrodes and established that GC microelectrodes demonstrate superior magnetic resonance compatibility over standard metal thin-film microelectrodes.Specifically,we demonstrated that GC microelectrodes experienced no considerable vibration deflection amplitudes and minimal induced currents,while Pt microelectrodes had significantly larger currents.We also showed that because of their low magnetic susceptibility and lower conductivity,the GC microelectrodes caused almost no susceptibility shift artifacts and no eddy-current-induced artifacts compared to Pt microelectrodes.Taken together,the experimental,theoretical,and finite element modeling establish that GC microelectrodes exhibit significant MRI compatibility,hence demonstrating clear clinical advantages over current conventional thin-film materials,further opening avenues for wider adoption of GC microelectrodes in chronic clinical applications.