Guitar pickups could be replaced with microscale film
The team coated a guitar tailpiece (the part of the instrument anchoring the guitar strings to the body) with a 10-micrometre-thick film called DiaForce. When the guitarist played, the information was sent from theelectrodes to a laptop, where a specifically designed software packagetranslates the movements -- including pitch bend and vibrato -- into a digital recording.
The key element to the design is the DiaForce film, created by the engineers at the Fraunhofer Institute for Surface Engineering and Thin Films IST. It is based on amorphous carbon and is piezoresistive. Saskia Biehl, head of the micro and sensor technology group, explains: "When the player changes the string tension, the pressure on the film changes. This in turn leads to a change in resistance, which is measured by electrodes on the film."
Biehl adds that the sensor can also measure the strength of the string vibration, "which would make it additionally possible to digitally represent the stroke strength and fading - regardless of whether the player plucks the strings with their fingers or a plectrum".
The engineers now intend to investigate whether the DiaForce coating could be mass-produced as a low-cost tension sensor for guitars. Coating tailpieces could, eventually, be an alternative to the traditional electromagnetic pickups used on electric guitars, which convert the string vibration into an electrical signal to create sound.
"We also want to extend its application to other musical instruments," Biehl says. "After all, force is exerted at various points on many string instruments, and so the possible applications are numerous."