Multiscale Bioelectronics Enabled by Ti₃C₂ MXene

Bioelectronic technologies are powerful tools to study, diagnose, and treat a wide variety of disorders. Examples of these technologies include implantable neuromodulation devices for neurological and mental disorders, peripheral nerve stimulators for pain and incontinence, wearable muscle sensors for rehabilitation and prosthesis control, and brain-computer interfaces. The vast majority of bioelectronic interfaces, however, still rely on noble metals and silicon, which are expensive to source and process and are intrinsically inadequate to address the mechanical, chemical, and electrical properties of excitable circuits in the body. Furthermore, manufacturing bioelectronic interfaces from these materials require fabrication schemes that are time-consuming, do not scale, and critically limit the maximum attainable resolution and coverage. Solution processing is a cost-effective manufacturing alternative, but biocompatible conductive inks matching the performance of conventional metals are lacking.<br/>Thanks to the remarkable combination of high electronic conductivity, high capacitance, biocompatibility, and processability from aqueous dispersions, Ti₃C₂ is emerging as an ideal candidate for replacing traditional materials and establish low-cost, additive-free, solution-based manufacturing of bioelectronic interfaces.<br/>Recently, we have developed a novel manufacturing approach to fabricate high-resolution electrodes based on Ti₃C₂MXene for recording and stimulation at high-resolution and multiscale, ranging from implantable neural electrodes for small rodents, all the way up to dry (i.e., gel-free) wearable sensors for brain (EEG), muscle (EMG), and cardiac (ECG) monitoring in humans.¹<br/>These novel electrode structures match – and in some cases exceed – the electrochemical impedance and stimulating charge injection performance of conventional bioelectronic materials such as Au and Pt. Furthermore, the low-density and magnetic susceptibility mismatch between Ti₃C₂and biological tissues enable artifact-free imaging with magnetic resonance (MRI) and computed tomography (CT), which is precluded when using metals such as Pt.<br/>To demonstrate the feasibility and versatility of this electrodes for multiscale bioelectronics, we show examples of a number of applications ranging from dry EEG for studying attention and cognition, to EMG for rehabilitation and prosthesis control, to invasive brain recording and stimulation in rodents and pigs.<br/>1. Driscoll, N., Erickson, B., Murphy, B. B., Richardson, A. G., Robbins, G., Apollo, N. V., ... & Gogotsi, Y. Medaglia, J.M, Vitale, F. (2021). MXene-infused bioelectronic interfaces for multiscale electrophysiology and stimulation. <i>Science Translational Medicine</i>, <i>13</i>(612), eabf8629.