A thin film stress gauge is a thin arrangement that can be sandwiched at the interface formed by two layers of the same or different materials and used to infer the time-resolved normal stress component of a longitudinal stress waves propagating through the interface. When a pressure is applied normal to the gauge, a state of stress is created around its sensing element, causing its thickness (and lines’ width for grid type gauges) and thus its electrical resistance to change (piezoresistive effect) or an electrical field to be produced across its element (piezoelectric effect). Therefore, there are two types of thin film stress sensors. They are the piezoresistive and the piezoelectric gauges. The piezoresistive gauge often requires an external pulse excitation source / bridge arrangement to increase its output without recoursing to signal amplification whereas the piezoelectric gauges generally do not. See Dynasen's excitation sources for pulse Power Supplies and Charge Converters. The output of a piezoresistive gauge, which in principle is nearly independent of its size and resistance, is usually expressed in terms of its relative or fractional change of electrical resistance versus stress. On the other hand, the output of a piezoelectric gauge is generally expressed by the amount of charge per unit area released by the action of the normal stress. Piezoresistive gauges are usually constructed into two nominal resistance's. They are the 50-Ohm and the low-impedance (0.050 Ohm) gauges. They bear two constructions which are the grid type and the strip type. The most commonly-used piezoresistive gauges are the Manganin (Cu:84%, Mn:12%, Ni:4%) and the Carbon gauges whereas the most utilized piezoelectric gauge is the PVF 2 (PVDF, Polyvenylidene Fluoride: CH2-CF2) gauge. See below a for typical ranges of applications of the four above stress gauges. All thin film stress gauges can be made with various element sizes, lead lengths and construction characteristics to accommodate numerous basic and practical applications. Contact Dynasen for information relating to choice and use of stress gauges. All stress gauges commercialized by Dynasen have been accurately calibrated using planar gas gun impact tests. Click here to download calibration sheets for our stress sensors. Goto: (Piezoresistive Stress Gauges - Carbon, Manganin), (Piezoelectric Stress Gauges-PVDF types)