Single chip measures pH, nitrate, phosphate and potassium in water

A single IC can measure pH, nitrate, phosphate and potassium levels in water, according to the Fraunhofer Institute for Photonic Microsystems, which has developed a way to monolithically combine multiple ion-sensitive field-effect transistors (isfets)

“Due to their resistance to breakage, isfets are already widely used in pH measurement technology, especially in food production,” according to the organisation. “Fraunhofer IPMS has now developed an n‑well technology that allows for the integration of several isfets in such a way that they can be specifically functionalised with ion-selective layers. In cooperation with research partners, further application-specific ion-selective coatings can be developed and integrated in the future.”

A pair of junction-isolated ion-sensitive fets on a ceramic substrate which (top photo) are coated with inert encapsulation for use

The sensor area in contact with the medium consists of a metal oxide layer if a pH sensor is required, or a PVC membrane with an ion-selective ionophore converts if it is to be a chemical sensor.

Two junction-isolated isfets (GOX and FOX = gate and field oxide) electrically-separated by a phosphorus-implanted n-well in a p-wafer

Applications are foreseen in environmental and bio analytics.

See the n-well integrated sensors and earlier single sensors at the Sensor+Test trade fair in Nuremberg, 11 – 13 June, stand 1-317.

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Steve Bush

Steve Bush is the long-standing technology editor for Electronics Weekly, covering electronics developments for more than 25 years. He has a particular interest in the Power and Embedded areas of the industry. He also writes for the Engineer In Wonderland blog, covering 3D printing, CNC machines and miscellaneous other engineering matters.