A new pH image sensor for applications including the treatment of Alzheimer’s disease has been developed by Kazuaki Sawada, a researcher at the Toyohashi University of Technology, Japan.

The pH imaging microscope device allows two dimensional and simultaneous visualisation of pH and optical imaging of chemical activity of solutions and cell activity.

The complementary metal oxide semiconductor (CMOS) technology is used in microprocessors, microcontrollers, static RAM, digital logic circuits, image sensors (CMOS sensor) and data converters.

CMOS comprises an array of charge-coupled devices (CCDs) covered with a functionalised membrane, monitoring pH distribution and yielding optical images of the test sample.

Sawada and his group are developing pH image sensors with one million pixels, with each pixel being 10×10 micrometres, while the current pH image sensors consist of 128×128 pixels, each with a sensing area of 10×25 micrometres.

The sensitivity of the new pH imaging sensor is 100 times greater than Ion Sensitive Field-Effect Transistor (ISFET) devices and allows the determination of pH differences of 0.0001 pH.

Sawada said they are planning to develop imaging devices for visualising the movement and distribution of other ions, including as calcium and sodium. The research team recently imaged changes in the distribution of acetylcholine (ACh) when nerve cells are stimulated with KCL, thereby leading to new methods for treatment of Alzheimer’s disease.

Sawada and his group are seeking industrial partners for the development of other applications of the pH image sensor.