M I C R O   S E N S O R   &   A C T U A T O R


 SAW Pressure Sensor  

Micro Systems Lab. in AJOU UNIVERSITY

Fig. 1. 440MHz SAW pressure sensor

Fig. 2. The measured S11 and sensitivity of the 440MHz SAW pressure sensor  

Surface Acoustic Wave-Based Pressure Sensor with Ground Shielding over Cavity on 41o YX LiNbO3
Keekeun Lee, Wen Wang, Geunyoung Kim, and Sangsik Yang

A 440MHz surface acoustic wave (SAW)-based pressure sensor was fabricated for stable mechanical compression force measurement.  A single-phase unidirectional transducer (SPUDT) and two acoustic tracks were employed to minimize inherent insertion loss and improve reflectivity of the reflectors.  The coupling of modes (COM) theory and finite element methods (FEMs) were used to determine optimal design parameters.  A LiNbO3 diaphragm was bonded to a heavily doped silicon substrate with a cavity ~250 µm deep, lined with gold to reduce the coupling loss of SAW energy to the surrounding atmosphere.  As a mechanical compression force was applied to the diaphragm, the diaphragm bent, resulting in phase shifts of the reflected peaks.  The phase shifts were modulated depending on the amount of mechanical compression applied.  The measured reflection coefficient S11 showed good agreement with simulated results.

Fig. 3. Wireless measurement system and the 2.4GHz SAW pressure sensor

Fig. 4. The measured S11 and sensitivity of the 2.4GHz SAW pressure sensor


  Related Papers

  1. Keekeun Lee, Jeangsu Hwang, Wen Wang, Geunyoung Kim, and Sangsik Yang,"Improving sensivity of SAW-based pressure sensor with metal ground shielding over cavity", Journal of the Microelectronics and packaging society, vol,12, No. 3, pp. 267-274, 2005
  2. Keekeun Lee, Jeangsu Hwang, Wen Wang, Geunyoung Kim, and Sangsik Yang, "Optimized Surface Acoustic Wave-based Pressure Sensor Using Equivalent Circuit Model", IEEE-NEMS, 2006, Zhuhai, China
  3. 김태현, 이기근, Wen Wang, 양상식, "고감도 SAW 기반 무전지 압력센서의 개발," 제8회 한국 MEMS 학술대회 논문집, pp.434-437, 2006. 04
  4. Wen Wang, Keekeun Lee, Insang Woo, Ikmo Park, and Sangsik Yang, "A Novel SAW based Pressure Sensor on 41° YX-LiNbO3", Asia-Pacific Conference of Transducers and Micro-Nano Technology, June, 2006, Singapore
  5. Wen Wang, Keekeun Lee, Jungsoo Hwang, Geunyoung Kim and Sangsik Yang, "Novel SAW-based Pressure Sensor on 41° YX-LiNbO3", Journal of the Institute of Electronics Engineers of Korea, 2006, vol43TC, No. 1, pp 33-39
  6. Wen Wang, Keekeun Lee, Sangsik Yang, and Ikmo Park, "Optimized design on SAW pressure sensor based on equivalent circuit model", Sensor and material, 2006(accept)
  7. Keedeun Lee, Wen Wang, Geunyoung Kim and Sangsik Yang, "Enhanced Sensitivity of SAW-based Pressure Sensor with Ground Shielding over Cavity on 41° YX-LiNbO3", Japanese Journal of Applied Physics, vol. 45, No. 7, 2006, pp 5974-5980
  8. K. Lee, W. Wang, I. Woo, S. Yang, and I. Park, "Long range wireless characterization of 2.4GHz SAW-based pressure sensor using network analyzer", Electric letters, 2006(accept)


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