Implantable thin-film porous microelectrode array (P-MEA) for electrical stimulation of engineered cardiac tissues

Abstract

We have designed, fabricated, and validated a novel porous, multielectrode array (P-MEA) device capable of low-voltage electrical stimulation of engineered cardiac tissues (ECTs). The primary advantage of this device is the ability to successfully function at a very low voltage thus minimizing any undesirable oxidative by-products in the culture environment or cell injury. Major features of our P-MEA include dimensions of 10 mm width and 82 mm length, four arms to allow movement of the individual pads within ECTs, each embedded electrode arm incorporates eight 100 µm×200 µm rectangular pores surrounding a 950 µm×340 µm exposed electrode, large pads on either side of the porous embedded device to function as current return electrodes, suture holes to aid in vivo suturing and stabilization, and an eight electrode connector pads. Average thickness of the Ni/Au electrodes was 20 nm of nickel and 400 nm of gold, an average electrode film thickness of 0.4 µm, and a double polyimide layer thickness of 16 µm. Electrode resistance ranged from 69.45 O to 78.52 O. Electrochemical impedance spectroscopy confirmed that the P-MEA operates in the 0.01 V to 1.0 V range with favorable charge transfer characteristics. Proof of principle experiments confirmed the ability of the P-MEA to effectively embed within ECT and electrically stimulate ECT during chronic, in vitro culture. Histology imaging shows that the embedding of the device has no adverse effects on the ECT and the cardiomyocytes are aligned within the tissue. Experiments are ongoing to evaluate the role of electrical stimulation on the maturation and function of ECTs.