Depths of the tips of the movable arrays can be adjusted in the brain after implantation.
It is known that the viability of micro arrays in the brain is limited by the chronic reaction of the brain tissue. Extensive efforts have been tried to reduce the time for recording good signals in the brain. We developed a special coating that significantly reduced this process. We have recently recorded the amygdala for more than a year with good multiunit signals in rats. In large animals such as dog, monkey, and etc, the viable time may last for several years. However, it may fail several years after implantation. This feature significantly limits the potential application in human. To overcome this problem, we develop this prototype of movable array.
Furthermore, the lay structures of the brain cortex justify the use of our movable array. The brain cortex includes several layers. These layers have relatively similar function. For example, the auditory cortex responding to sounds has iso-frequency across layers, whereas the sensory cortex has individual barrels across the layers. These special features can be used in the brain-machine interface (BMI). For example, when the original sites of the brain failed to record good signals, our movable arrays will mitigate to a fresh site that has the same function as the previous one, establishing another period of recording and/or stimulation. By this way, viability of movable arrays will be significantly extended. It may last many years before it finally fails, making it possible for human use.