Fabrication of a 128 $,\times,$ 128 Pixels Charge Transfer Type Hydrogen Ion Image Sensor

The charge transfer technique, which is capable of operating in charge accumulation-mode, is suitable for use in pH-imaging to detect small changes in potential. An advanced charge-transfer-type hydrogen ion image sensor consisting of 128 × 128 pixels with a 23-μm pixel pitch is fabricated. A new scanning system and high-performance drive buffer circuits are adopted to achieve high frame rates. For miniaturization of the sensor pixels, we developed an advanced new fabrication process. The pH sensitivity is 32.8 mV/pH when using standard pH solutions. Videos of the movement of hydrogen ions are clearly obtained with the 128 × 128 pixels display, and photo images are taken simultaneously with the videos of the movement of hydrogen ions. A frame rate of 58 frames per second is realized with this image sensor.