Browsing by Author "Cain, Markys G."

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    Characterisation of PZT thin film micro-actuators using a silicon micro-force sensor
    (Elsevier, 2007-01-08) Duval, Fabrice F. C.; Wilson, Stephen A.; Ensell, Graham; Evanno, Nicolas M. P.; Cain, Markys G.; Whatmore, Roger W.
    This paper reports on the measurements of displacement and blocking force of piezoelectric micro-cantilevers. The free displacement was studied using a surface profiler and a laser vibrometer. The experimental data were compared with an analytical model which showed that the PZT thin film has a Young's modulus of 110 GPa and a piezoelectric coefficient d31,f of 30 pC/N. The blocking force was investigated by means of a micro-machined silicon force sensor based on the silicon piezoresistive effect. The generated force was detected by measuring a change in voltage within a piezoresistors bridge. The sensor was calibrated using a commercial nano-indenter as a force and displacement standard. Application of the method showed that a 700 μm long micro-cantilever showed a maximum displacement of 800 nm and a blocking force of 0.1 mN at an actuation voltage of 5 V, within experimental error of the theoretical predictions based on the known piezoelectric and elastic properties of the PZT film.
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    Flextensional ultrasonic piezoelectric micro-motor.
    (IEEE Institute of Electrical and Electronics, 2006-12-01T00:00:00Z) Leinvuo, Joni T.; Wilson, Stephen A.; Whatmore, Roger W.; Cain, Markys G.
    This paper presents the experimental design, construction, and operational characteristics of a new type of standing wave piezoelectric ultrasonic micro-motor. The motor uses a composite stator, consisting of a metallic flextensional mode converter, or "cymbal," bonded to a 2-mm-square piezoelectric plate. The cymbal converts contour-mode vibrations of the plate into oscillations in the cymbal, perpendicular to the stator plane. These are further converted into rotational movement in a rotor pressed against the cymbal by means of an elastic-fin friction drive to produce the required rotary actuation. The motor operates on a single-phase electrical supply, and direct control of the output speed and torque can be achieved by adjusting the amplitude and frequency of the supply voltage. Noncontact optical techniques were used to assess the performance of the developed micro-motor. The operational characteristics were developed from the acceleration and deceleration characteristics. No-load output speed (11 rev s-1) and stall torque (27 nNm) were derived using high-speed imaging and image analysis. Maximum efficiency was 0.6%
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    A new flextensional piezoelectric ultrasonic motor - design, fabrication and characterisation
    (Elsevier, 2007-01-08) Leinvuo, Joni T.; Wilson, Stephen A.; Whatmore, Roger W.; Cain, Markys G.
    This paper presents the techniques used for the characterisation of a new type of standing-wave piezoelectric ultrasonic motor. The motor uses a metallic flextensional amplifier, or “cymbal”, to convert the radial mode vibrations of a piezoelectric ceramic disc into flexural oscillations, which are further converted to produce rotary actuation by means of an elastic fin friction drive. The motor operates on a single-phase electrical supply. A beryllium copper rotor design with three-fin configuration was adopted. The best stall torque, no load speed, transient time and efficiency for a 25 mm motor were 2 N mm, 680 rpm, 2 ms and 4.8%, respectively. The operational characteristics of the motor were evaluated by using two methods: one based on the pulley–brake principle and one on high-speed imaging. The results obtained from using these two techniques are contrasted and compared.