Realization of CMOS-Based Multimodal Image Sensor for Three-Dimensional Force and PH Measurement

We realized a CMOS-based multimodal image sensor for measuring three-dimensional force and pH for the first time. Using semiconductor photolithography, the force-sensitive region, which consisting of a piezoelectric film and a MEMS microstructure array (A single-element; <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$8\times 8\ \mu \mathrm{m}$</tex>), and the pH-sensitive region were constructed on a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2\ \mu \mathrm{m}-\text{pitch}$</tex> CMOS potentiometric array sensor. Based on visualization experiments to detect force and pH response, the clear output image was observed due to force change on a single microstructure and pH change in a solution, demonstrating multimodal sensing on the fabricated sensor.