A multiplexer system for multi-channel charge signal processing in in-shoe force measurement

This paper describes the theory and design of a novel charge signal multiplexer (MUX) system utilizing a single charge amplifier, which is developed for multi-channel input from piezoelectric transducers. The original purpose of the design was to process charge signals from a set of tri-axial piezoelectric transducers developed for in-shoe force measurements. The goal was to reduce the number of charge amplifiers required to process multi-channel charge signals and simplify the circuit. With inputs from piezoelectric transducers, this multiplexing process results in a voltage output which is proportional to the change in magnitude of the input charge signal between samples. The multiplexed data is then acquired and reconstructed for analysis and display. In this paper, the theory, design and initial testing of an 8 channel system utilizing one single charge amplifier are described. The advantages and disadvantages of this charge multiplexer system are discussed. The results of experiments show that this charge multiplexer system is capable and suitable for multi-channel charge signal processing.