In this application is described substrates for high-throughput assays of clostridial neurotoxin proteolytic activities. The sensor drive controller changes the frequency of the sensor drive signal to avoid frequencies and associated harmonics at which noise occurs and which could interfere with the sensor signal. The timing overlap may also be synchronized with a periodic ripple component in the strobe illumination, to provide improved repeatability. Further, methods of controlling the yield of the EPM elastomer and of recovering the EPM elastomer are provided. Preferably, the broadcast medium is an infrared communications channel.