Biofabrication of a Low Modulus Bioelectroprobe for Neurons to Grow Into

Implantable nerve electrodes, as a bridge between the brain and external devices, have been widely used in areas such as brain function exploration, neurological disease treatment and human–computer interaction. However, the mechanical properties mismatch between the electrode material and the brain tissue seriously affects the stability of electrode signal acquisition and the effectiveness of long-term service in vivo. In this study, a modified neuroelectrode was developed with conductive biomaterials. The electrode has good biocompatibility and a gradient microstructure suitable for cell growth. Compared with metal electrodes, bioelectrodes not only greatly reduced the elastic modulus (<10 kpa) but also increased the conductivity of the electrode by 200 times. Through acute electrophysiological analysis and a 12-week chronic in vivo experiment, the bioelectrode clearly recorded the rat’s brain electrical signals, effectively avoided the generation of glial scars and induced neurons to move closer to the electrode. The new conductive biomaterial electrodes developed in this research make long-term implantation of cortical nerve electrodes possible.

Package Architecture and Component Design for an Implantable Peripheral Nerve Stimulation and Recording System for Advanced Prosthetics

One of the limitation of current prosthetics is the ability to provide sensory feedback to the human user. Due to this constraint, approximately 60–80 percent of amputees experience a phenomenon known as phantom limb pain, an ongoing painful sensations that to the individual, seems to be coming from the part of the limb that is no longer there. The lack of sensory feedback also limits the intuitive control of the user's hand movement, i.e. sense of grip or position. To address these limitations, we created am implantable system that could provide peripheral nerve stimulation, recording and motor control. The architecture of our Sensory-Stimulation Lead (SSL) system consist of multiple satellites connected to Draper's custom designed nerve electrodes. In this phase of the design, the implanted system is connected to a controller via percutaneous connections. The active electronics of the satellite is enclosed in a hermetic package approximately 14mm in diameter and less than 5mm thick. A custom ceramic feedthrough substrate provides the electrical connections of the internal electronics board to both the nerve electrodes and percutaneous leads. In this paper, we will describe the various packaging components of the system and the design, fabrication, and assembly considerations that drove our technology choices.