Microelectrode arrays (MEAs) have proved to be useful tools for characterizing electrically active cells such as cardiomyocytes and neurons. While there exist a number of integrated electronic chips for recording from small populations or even single cells, they rely primarily on the interface between the cells and 2D flat electrodes. Here, an approach that utilizes residual stress‐based self‐folding to create individually addressable multielectrode interfaces that wrap around the cell in 3D and function as an electrical shell‐like recording device is described. These devices are optically transparent, allowing for simultaneous fluorescence imaging. Cell viability is maintained during and after electrode wrapping around the cel and chemicals can diffuse into and out of the self‐folding devices. It is further shown that 3D spatiotemporal recordings are possible and that the action potentials recorded from cultured neonatal rat ventricular cardiomyocytes display significantly higher signal‐to‐noise ratios in comparison with signals recorded with planar extracellular electrodes. It is anticipated that this device can provide the foundation for the development of new‐generation MEAs where dynamic electrode–cell interfacing and recording substitutes the traditional method using static electrodes.

Electrogenic cells such as cardiomyocytes and neurons rely mainly on electrical signals for intercellular communication. Microelectrode array (MEA) devices have been developed to both record and stimulate electrogenic cell. This technology is fuels new insights in the operation of electrogenic cells and the operation of the brain, and is particularly suitable for long-term recording of cell signals under low cell stress conditions. To date, microelectrode arrays are relying on flat or needle shaped electrode surfaces, mainly due to limitations in the lithographic processes used to fabricate these electrodes. However, cells are intrinsically three-dimensional (3D), and this paper relies on a previously reported elasto-capillary aggregation process, to create 3D carbon nanotube (CNT) MEAs. We found that CNTs aggregated in well-shaped structures of similar size as cardiomyocytes are particularly interesting for MEA applications. This is because (i) CNT microwells of the right diameter preferentially trap individual cardiomyocytes , which facilitates single cell recording without the need for clamping pf cells or deconvolution of signals, and (ii) once the cells are trapped inside of the CNT wells, this 3D CNT structure is used as an electrode surrounding the cell, which increases the cell-electrode contact area and as a result we found that the recorded output voltages increase significantly(up to more than 200%). Further, our fabrication process allows for a large library of 3D geometries in a scalable fashion, which paves the way for future study of complex interactions between electrogenic cells and 3Drecording electrodes.

No abstract

While there is a growing need for soft and 3D cell interfacing, present‐day microelectrode arrays are largely rigid and planar. In article number https://doi.org/10.1002/advs.201700731, Dries Braeken, David H. Gracias, and co‐workers realize flexible multielectrode shells that can wrap around cardiomyocytes, allowing parallel readout of all cardinal points of the cell with higher signal‐to‐noise ratios compared to planar electrodes.