Bioresorbable Electrode Array for Electrophysiological and Pressure Signal Recording in the Brain

: Medical implantation of an electrocorticography (ECoG) recording system for brain monitoring is an effective clinical tool for seizure focus location and brain disease diagnosis. Planar and flexible ECoG electrodes can minimize the risks of infection and serious inflammatory response, and their good shape adaptability allows the device to fit complex cortex shape and structure to record brain signals with high spatial and temporal resolution. However, these ECoG electrodes require an additional surgery to remove the implant, which imposes potential medical risks. Here, a novel flexible and bioresorbable ECoG device integrated with an intracortical pressure sensor for monitoring swelling of the cortex during operation is reported. The ECoG device is fabricated with poly(l-lactide) and polycaprolactone composite and transient metal molybdenum. In vivo tests on rats show that the ECoG system can record the dynamic changes in brain signals for the different epilepsy stages with high resolution, while the malleable pressure sensor shows a linear relationship between the pressure and resistance in in vitro tests. In vitro degradation experiments show that the ECoG system can work stably for about five days before loss of efficacy, and the whole ECoG system degrades completely in a phosphate buffer solution in about 100 days.