W.J. Wu

Publications (3)2.11 Total impact

• Article: Fabrication and Evaluation of a MEMS Piezoelectric Bimorph Generator for Vibration Energy Harvesting

  B. S. Lee, S. C. Lin, W. J. Wu
  [show abstract] [hide abstract]
  ABSTRACT: We present the development of a MEMS piezoelectric bimorph generator, a cantilever type bimorph which was formed by laminating two PZT piezoelectric layers. Our bimorph generator can scavenge mechanical energy from ambient vibrations and transform it into useful electrical energy. Two poling configurations of the PZT piezoelectric layers of our bimorph MEMS generator were fabricated and tested. A tip proof mass used for adjusting the resonance frequency was also demonstrated. Experimental results confirm that our device possessed a maximum open-circuit output voltage of 1.91VP-P and a 3.42VP-P for a parallel polarization device and a serial polarization device, respectively with a 2g externally applied vibration. At an optimal resistive load, the maximum output power was 1.548μ–W and 1.778μ–W for a parallel polarization device and a serial polarization device, respectively.
  Journal of Mechanics. 11/2010; 26(04):493 - 499.
• Conference Proceeding: Multi-cantilever piezoelectric MEMS generator in energy harvesting

  S.C. Lin, B.S. Lee, W.J. Wu, C.K. Lee
  [show abstract] [hide abstract]
  ABSTRACT: In this paper, we present the development of a multi-cantilever piezoelectric MEMS generator, which has the ability to scavenge mechanical energy of ambient vibrations and transforms it into useful electrical power. The generator comprises four cantilever type devices, two d₃₁ mode devices and two d₃₃ mode devices, which were made by a silicon process in a single die. We developed a PZT deposition machine which uses an aerosol deposition method to fabricate the PZT thin film efficiently. The four cantilever devices can be connected in series or in parallel so as to possess different output characteristics. The measurement results show that our prototype device possesses resonance frequencies between 237 Hz and 244.5 Hz.
  Ultrasonics Symposium (IUS), 2009 IEEE International; 10/2009
• Article: Piezoelectric MEMS generators fabricated with an aerosol deposition PZT thin film

  B S Lee, S C Lin, W J Wu, X Y Wang, P Z Chang, C K Lee
  [show abstract] [hide abstract]
  ABSTRACT: In this paper, we present the development of two piezoelectric MEMS generators, {3–1} mode and {3–3} mode, which have the ability to scavenge mechanical energy of ambient vibrations and transform it into useful electrical power. These two piezoelectric MEMS generators are of cantilever type made by a silicon process and which can transform mechanical energy into electrical energy through its piezoelectric PZT layers. We developed a PZT deposition machine which uses an aerosol deposition method to fabricate the high-quality PZT thin film efficiently. Our experimental results show that our {3–1} mode device possesses a maximum open circuit output voltage of 2.675 VP-P and a maximum output power of 2.765 µW with 1.792 VP-P output voltage excited at a resonant frequency of 255.9 Hz under a 2.5 g acceleration level. The {3–3} mode device possessed a maximum open circuit output voltage of 4.127 VP-P and a maximum output power of 1.288 µW with 2.292 VP-P output voltage at its resonant frequency of 214 Hz at a 2g acceleration. We also compared the output characteristics of both the {3–1} mode and the {3–3} mode piezoelectric MEMS generators which were both excited at a 2g acceleration level.
  Journal of Micromechanics and Microengineering 05/2009; 19(6):065014. · 2.11 Impact Factor