Piezo film sensors are basically capacitors that develop charge within their dielectric, and are therefore very high impedance devices. It is very common to connect a sensor with one electrode connected to electrical ground, and the other as "signal". But this signal electrode may be very susceptible to electrical interference, unless another grounded surface is brought very close. It is sometimes possible to fold over a film element so that the ground electrode completely shields the signal electrode (our SDT1-028K element uses this principle). It is also possible to add a further ground electrode over the signal electrode by lamination, or simply to place the sensor within a shielded enclosure, or in close proximity to a large grounded plane. The wires connecting the sensor to an electronic circuit are also susceptible to electrical pick-up, and should be trimmed as short as possible, or if necessary replaced with shielded or coaxial cable.