A special IC, so called IntegratedSensor-Heater Constant Temperature Rectifying Circuit, has been developed for SJ-2 DigitalEddy CurrentDisplacement and Vibration-AmplitudeMeter.
That may not sound much, but Mr Lau points out that it actually has 3.9m sensors, so that it comfortably outperforms a conventional 2.0-megapixel sensor.