Flexible Microelectrode Arrays with Enhanced Electrochemical Properties Using Platinum Ditelluride

Invasive penetrating microelectrode arrays are essential tools for interfacing with and understanding the central and peripheral nervous systems. They enable advances in basic neuroscience, the diagnosis and treatment of neurological and neuropsychiatric disorders, and the development of brain–computer interfaces. Efforts to increase spatial resolution have driven device miniaturization and higher channel counts, but these improvements are often constrained by high impedances and limited charge injection capacity of the electrode materials commonly used. In addition, conventional microelectrode arrays are fabricated with stiff materials (Young’s modulus on the order of hundreds of GPa) compared to ultrasoft brain tissue (0.1–10 kPa). This mechanical mismatch contributes to a neuroinflammatory response caused by micromotion between the array and the brain. Here, we show that microelectrode arrays made of platinum ditelluride (PtTe2), a class of nano 2D materials known as thin transition metal dichalcogenides, sandwiched between polyimide insulating layers are not only mechanically compliant but also exhibit 2 times lower impedance (3.8 ± 0.4 Ω·cm2), 9 times higher charge storage capacity (7.4 ± 0.6 mC·cm–2), and 2 times higher charge injection capacity (0.058 ± 0.0031 mC·cm–2) than platinum microelectrodes. Furthermore, PtTe2 arrays were subjected to accelerated aging at 63 °C PBS for 15 days (equivalent to 91 days at 37 °C) and 39% of functional channels from Array B survived. Five million current pulses were passed through the electrodes, and 40% and 28% of functional channels from Arrays C and D survived, respectively. Mechanical testing revealed a buckling force of 0.8 ± 0.1 mN, Young’s modulus of 2.9 ± 0.5 GPa, and bending stiffness of 5.8 ± 0.9 pN·m2. Finally, we demonstrated in vivo functional viability of the PtTe2 arrays in an anesthetized rhesus macaque for the first time. We propose PtTe2 as a material for the next generation of flexible neural microelectrode arrays.