A scanning chemical microscope utilizing a flat pH sensor has proven effective for analyzing a number of biological specimens including human teeth surfaces, plant leafs, and rice.

The key to this microscope, the “pH imaging sensor”, is an electrochemical semiconductor that can be made to function as an array of point sensors when scanned by backside laser illumination. Measured pH values at each measurement point can be processed into a pH image. So far a resolution of 5 μm with a 0.01 pH sensitivity has been attained by this imaging technology, although most images are made using 100 μm resolution. The time to acquire an image is, of course, dependent on the size of the measured area. For example, a 6.4 mm x 6.4 mm image with a resolution of 100 urn can be acquired in 25 s. Linear pH profiles can also be obtained at a speed of 1 cm/s.