Signal processing for PVDF sensor in cell injection

Cell injection is an important and difficult process, and with current technology, injections are completed manually and have a low success rate. It is proposed that the addition of haptic feedback to the injection process may increase the accuracy, repeatability and success rate of cell injection. Before haptic control can be integrated into the system, a method to reliably measure the mN-μN forces involved in cell injection must be investigated. This requires the reliable characteristic of input force and control parameters. A piezoelectric polymer called Polyvinylidene Fluoride (PVDF) which produces voltage when it experiences force was investigated for this purpose. Experiments show that during the cell injection process the output voltage produced by PVDF has the properties including small amplitude, low signal to noise ratio, and uncertainty. Therefore, in order to obtain a reliable relationship between the cell injection force and the output voltage, a subsystem to monitor the sensor output voltage has to be designed with capability of gain controllable amplifying, filtering and achieving signal processing. This paper presents the design of the subsystem and its performance capabilities.