Hab ich gerade gefunden, IIRC hat hier jemand vor einigerzeit mal nach Piezo Motoren gesucht. Hört sich interessant an. Der hier arbeitet mit sehr kleinen Spannungen und 0,5u bei 10mm/s iss auch nett.
[...] to develop the world's smallest linear motor that is powered directly by a battery voltage of 2.8 V. With a length of 6 mm, its height and width are just 1.55 mm².The motor consists of a threaded pin running inside a threaded nut. Activating the ultrasonic resonator causes the nut to oscillate torsionally and drive the threaded pin forward and back. This simple and rugged construction allows forward speeds of up to 10 mm/s with a resolution as fine as 0.5 µm to be attained. The operating frequency of the piezo resonators is in the ultrasound range of 150 kHz.
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Saludos Wolfgang