QCM Coupled Resonating Systems under Vacuum – Sensitivity and Characteristics

150 150 MIMOS Berhad


Mohammad Ali Mohammadzadeh Kashan; Vineetha Kalavally; Purabi Mazumdar; Hing Wah Lee and N. Ramakrishnan



We present  the  underlying  physics in  the resonance frequency  characteristics  of a bare  quartz  crystal  microbalance(QCM) and a QCM-micro pillar based coupled resonator sensor (QCM-CRS)  when  they  were  subjected  to pressure changes in  a vacuum   chamber.   The   QCMs experienced   an   increase   in resonance frequency with decrease in pressure due to an inverse mass loading effect  introduced  on  the  QCM  surface. However, when  the  pressure  (below  atmospheric  pressure)  dominated  the mass  loading,  the resonance  frequency of  QCMs  decreased.  A sensitivity  increase  of  11  times  to    the  pressure  changes  was observed for case of QCM-CRS  made of resonating micropillars attached  around  the  central  region  of  the  electrode. Also  the resonance   frequency   shift   was linear for   pressure   changes between  31 kPa and 71kPa,  demonstrating  the  possibility  of employing  QCM-CRS  vacuum  detector  element.  The  proposed sensor element is envisioned to have wide industrial applications ranging  from  detecting  vacuum  in chambers  used  in  coating systems to crack detection in closed chambers.



IEEE Sensors Journal