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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 40: POSTERS Electronic and Optical Properties

CPP 40.19: Poster

Donnerstag, 26. März 2009, 17:00–19:30, P3

Electroactive Polymers for Flexible and Conformable Touchpads and Keyboards — •Gerda Buchberger, Reinhard Schwödiauer, Nikita Arnold, and Siegfried Bauer — Johannes Kepler Universität, Linz, Österreich

Cellular polypropylene ferroelectrets are flexible, lightweight and piezoelectric transducer materials, which are used in a wide range of sensing applications. We fabricated and characterized a ferroelectret touchpad of 10x10 cm2. It consists of a ferroelectret film that is placed between two large area electrodes. Electrical ports are fixed to the corners of the device. If a force is applied, transient voltage signals can be measured due to the piezoelectric effect. The voltage amplitudes depend on the touch position. In addition to the touchpad we fabricated keyboards using a binary coding technique profiting from the polarization states of the ferroelectret. Functional layers with a polarization pattern are covered by large area electrodes and stacked afterwards. The keys are encoded by the sequence of the polarization states. If a force is applied to a key, the corresponding transient voltage signals are measured at the edges of the device for every layer. As the polarization pattern and therefore the signal sequence is characteristic for every key it can be determined unambiguously. As we use large area electrodes combined with contacts only at the edges, sensor matrices are avoided. The concepts can be further extended to flexible transparent devices using polyvinylidene fluoride and transparent electrodes. The devices may be used for rollable touchpads and keyboards, for consumer goods as intelligent price tags and for whole body tactile sensors.