Biomedical microimplants for sensory and motor neuroprostheses

Neuroprostheses are devices that directly interface a technical implant with the human nervous system to restore sensory or motor function or to modulate the central nervous system properties after traumatization or severe diseases, respectively. Nowadays, cochlea implants help the deaf to hear and bladder stimulators control the micturition in spinal cord injuried subjects. Deep brain stimulation of patients with Parkinson´s disease suppresses tremor and electrical stimulation of the spinal cord modulates the hyperactive bladder. Research is done in various fields for several challenging applications to make the blind see and the lame walk with the help of neural prostheses. Microsystem technology offers tremendous opportunities in this field due to its inherently high degree of minaturization. Flexible and light-weighted multichannel devices to interface the nervous system have been developed. Materials like polyimide and parylene C were combined with medical grade silicone rubbers to assemble flexible microimplants with recording and stimulation circuitry, telemetric signal and energy transmission. Some examples will be discussed in this paper to give an overview of possibilities and limitations of this technological approach