32×32画素パルス周波数変調方式人工視覚イメージセンサ

抄録

We demonstrated a CMOS image sensor using pulse frequency modulation (PFM) for retinal prosthesis. We are fabricated the 32x32 pixel PFM image sensor with standard 0.6μm CMOS technology. We designed this chip for use in in vitro electro-physiology experiments. The image sensor pixel was composed of a PFM-based photosensor with a frequency limiter, a pulse shaper/amplifier, and a stimulus electrode. We measured the image sensor response vs. the illumination level. We further verified the pulse shaper/amplifier characteristics. By using the current output from the stimulus electrode, we successfully demonstrated positive and negative current output of 100μA driving an external electrode placed inside a multi-electrode array immersed in saline. This result shows that this chip could be used in vitro electro-physiology experiments. To observe the output pulse from the sensor, we used the LED display in order to visualize the input scene from each pixel output pulses, and demon-strates the visualization successfully.