How do piezo pick-ups work with strings?
Piezo pick-ups are basically pressure sensors, or strain gauges. Piezo sensors convert mechanical energy into electrical energy. They are able to detect micro levels of pressure caused by some force exerted on them. In the case of a guitar string, it is the mechanical force of vibration that causes a frequency cycle of pressure pulses. Piezoelectric sensors are typically made up of several layers of elastic materials that combine to generate electricity. In theory, a material property of all elastic solids, Young’s modulus (Y) is used to describe “stiffness” of materials. When rod or plate of cross section (A) and length (L) is pulled with force (F) resulting in an elongation (Δ L), the Young’s modulus can be computed as follows: Y = (L/A)*(F/ΔL) In piezo applications Y is frequently used to estimate the equivalent spring constant of a rod or a plate of material that is in contact with a piezo actuator (F/ΔF).
