Ultra-compact, zero-power magnetic latching piezoelectric inchworm motor with integrated position sensor

Abstract This paper reports the design, fabrication and characterization of a large-stroke, piezoelectrically actuated linear motor with zero-power latching for portable electronics. The motor consists of a stator having a micromachined piezoelectric actuator and a high-permeability metal guide, a permanent magnet rotor, and an integrated position sensor. The rotor is tethered to the metal guide by magnetostatic attraction due to its permanent magnets. The resulting frictional forces are sufficient to immobilize the rotor to the stator. This does not require any power, and the combined bearing-braking feature is thus termed zero-power latching. The integrated position sensor demonstrates the feasibility of precisely monitoring the rotor position. The completed actuator has a volume of 1 mm(w) × 3 mm(t) × 5 mm(l). With a 50 kHz driving frequency, precision of 5 μm at a scalable full-stroke of 5 mm and a speed of 10 mm/s at 50 kHz was achieved. A capacitive position sensor was also designed into the motor, and was able to determine the rotor position with a sensitivity of 1 fF/μm.

[1]  Don L. DeVoe,et al.  Large-force electrothermal linear micromotors , 2004 .

[2]  Norman C. Tien,et al.  Low voltage electrothermal vibromotor for silicon optical bench applications , 2000 .

[3]  Jong Hyun Lee,et al.  Characterization of a micromachined inchworm motor with thermoelastic linkage actuators , 2002, Technical Digest. MEMS 2002 IEEE International Conference. Fifteenth IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.02CH37266).

[4]  K. Pister,et al.  Single mask, large force, and large displacement electrostatic linear inchworm motors , 2002 .

[5]  A. H. Sonnenberg,et al.  Surface micromachined linear electrostatic stepper motor , 1997, Proceedings IEEE The Tenth Annual International Workshop on Micro Electro Mechanical Systems. An Investigation of Micro Structures, Sensors, Actuators, Machines and Robots.

[6]  Victor M. Bright,et al.  Automated assembly of flip-up micromirrors , 1998 .

[7]  T. Hemsel,et al.  Survey of the present state of the art of piezoelectric linear motors , 2000, Ultrasonics.

[8]  Ernst Obermeier,et al.  Microactuators and their technologies , 2000 .

[9]  Eui-Hyeok Yang,et al.  A normally latched, large-stroke, inchworm microactuator , 2007 .

[10]  R. Muller,et al.  Linear microvibromotor for positioning optical components , 1995 .

[11]  W. Benecke,et al.  Linear and rotational magnetic micromotors fabricated using silicon technology , 1992, [1992] Proceedings IEEE Micro Electro Mechanical Systems.

[12]  B. Ziaie,et al.  Frequency Controlled Bidirectional Ratcheting Biomimetic Motion , 2006, 19th IEEE International Conference on Micro Electro Mechanical Systems.

[13]  Jong-Uk Bu,et al.  Ultra-Compact, Zero-Power Latching Linear Motor with Integrated Position Sensor for Portable Electronics , 2007, TRANSDUCERS 2007 - 2007 International Solid-State Sensors, Actuators and Microsystems Conference.