Pharmaceutical Pill Counting and Inspection Using a Capacitive Sensor

A capacitive sensor for high-speed counting and inspection of pharmaceutical products is proposed and evaluated. The sensor is based on a patented Electrostatic Field Sensor (EFS) device, previously developed by Sparc Systems Limited. However, the sensor head proposed in this work has a significantly different geometry and has been designed with a rectangular inspection aperture of 160mm × 21mm, which best meets applications where a larger count throughput is required with a single sensor. Finite element modelling has been used to simulate the electrostatic fields generated within the sensor, and as a design tool for optimising the sensor head configuration. The actual and simulated performance of the sensor is compared and analysed in terms of the sensor performance at discriminating between damaged products or detection of miscount errors.