Uncommon sense

A sensor that will allow doctors to measure the electrical activity of patients' hearts without touching them could also be used for more accurate non-destructive testing of carbon composite aircraft parts and microchips. Engineers from the

have developed prototypes for these applications using electric potential sensors (EPSs).

Similar devices, which measure magnetic fields, already exist in medicine and industry. However, the EPS offers a non-invasive way of measuring lesser-explored electrical fields, present wherever there is electrical activity. It works like a remote electrocardiogram, which is used to record the electrical activity of a patient's heart.

The system consists of a single sensor, a three-axis computer position controlling scanning system and signal processing hardware. It measures the electrical conductivity above the surface of a material sample by the application of a small AC current. The sensor scans the surface to measure the conductivity and location of possible defaults. If fibres in the material are damaged, the sensor will detect an electrical resistance in that area and a colour change will be displayed on the computer image screen.