Stretchable micro-electrode arrays (SMEAs) are useful tools to study the electrophysiology of living cells seeded on the devices under mechanical stimulation. For such applications, the SMEAs are used as cell culture substrates; therefore, the surface topography and mechanical properties of the devices should be minimally affected by the embedded stretchable electrical interconnects. In this paper, a novel design and micro-fabrication technology for a pneumatically actuated SMEA are presented to achieve stretchability with minimal surface area dedicated to the electrical interconnects and a well-defined surface strain distribution combined with integrated diverse micro-patterns to enable alignment and directional stretching of cells. The special mechanical design also enables the SMEA to have a prolonged electro-mechanical fatigue life time required for long-term cyclic stretching of the cell cultures (stable resistance of electrical interconnects for more than 160 thousand cycles of 20% stretching and relaxing). The proposed fabrication method is based on the state of the art micro-fabrication techniques and materials and circumvents the processing problems associated with using unconventional methods and materials to fabricate stretchable electrode arrays. The electrochemical impedance spectroscopy characterization of the SMEA shows 4.5 M impedance magnitude at 1 kHz for a TiN electrode 12 um in diameter. Cell culture experiments demonstrate the robustness of the SMEAs for long-term culturing experiments and compatibility with inverted fluorescent microscopy.

A novel stretchable Micro-Electrode Array (MEA) for biomedical applications with robust spiraled interconnects and radial micro-grooves for cell alignment is presented, enabling the unique combination of alignment, mechanical stimulation, and electrical characterization of living cells. Many of the problems normally associated with the fabrication of interconnects and electrodes on stretchable PDMS (Polydimethylsiloxane) membranes have been eliminated by first fabricating the interconnects and then spin-coating the PDMS. Experiments supported by Finite Element simulations demonstrate the robustness of the new spiraled interconnect design. The alignment of cells to micro-molded grooves is demonstrated, allowing for directional stretching of the cells.

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A novel fabrication process for CNT micro-electrode arrays (MEA) integrated on stretchable Polydimethylsiloxane (PDMS) membranes is presented. The new process flow overcomes the problems encountered in previous reports. In the process flow presented in this paper, Carbon nanotubes (CNT) electrodes are embedded on the backside of a freestanding membrane using a novel fabrication technique. This upsidedown CNT MEA consists of micro-electrodes with an area of 110 µm 2 covered with Cobalt-grown CNTs. The recorded electrochemical impedance values confirm the effectiveness of the proposed design: at 1 kHz the fabricated CNT-MEA electrodes show a reduction of the overall impedance by 95 % in comparison to benchmark TiN electrodes. CNT-MEA impedance is 240 kΩ against 2.2 MΩ of the TiN MEA. The quality of the CNTs was assessed with Raman spectroscopy and the biocompatibility of fabricated CNT-MEA device is demonstrated by the plating of human pluripotent stem cell-derived cardiomyocytes on the CNT electrodes.

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