A low pull-in SU-8 based Capacitive Micromachined Ultrasonic Transducer for medical imaging applications

In this paper we present a thorough analysis of a low pull-in voltage Capacitive Micromachined Ultrasonic Transducer (CMUT) using SU-8 as the membrane material. It is designed to operate at 1 MHz frequency that has a wide range of applications including the imaging of deeper organs. We also propose a simple state-of-the-art fabrication methodology for the same. As compared to the standard Silicon Nitride CMUTs, the proposed structure gives the same electromechanical coupling coefficient with lower membrane dimensions and low pull-in voltage which in turn results in reduced area and power consumption. Moreover the proposed fabrication methodology is a low temperature process which makes it CMOS compatible.

[1]  A bonding technique using hydrophilic SU-8 , 2007 .

[2]  P. Reynolds,et al.  Finite‐element method for determination of electromechanical coupling coefficient for piezoelectric and capacitive micromachined ultrasonic transducers , 2000 .

[3]  K. Oh,et al.  Flip-chip packaging using micromachined conductive polymer bumps and alignment pedestals for MOEMS , 1999 .

[4]  Butrus T. Khuri-Yakub,et al.  Capacitive Micromachined Ultrasonic Transducers: Theory and Technology , 2003 .

[5]  O. Oralkan,et al.  Capacitive micromachined ultrasonic transducers: fabrication technology , 2005, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[6]  B.T. Khuri-Yakub,et al.  Analytically calculating membrane displacement and the equivalent circuit model of a circular CMUT cell , 2008, 2008 IEEE Ultrasonics Symposium.

[7]  S.J. Ballandras,et al.  Theoretical analysis of micro-machined ultrasonic transducer using a simple 1-D model , 2006, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[8]  Rudra Pratap,et al.  Elasto-Electrostatic Analysis of Circular Microplates Used in Capacitive Micromachined Ultrasonic Transducers , 2010, IEEE Sensors Journal.

[9]  B. Khuri-Yakub,et al.  Surface micromachined capacitive ultrasonic transducers , 1998, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[10]  Peter R. Hoskins,et al.  Diagnostic ultrasound : physics and equipment , 2010 .

[11]  D. Nampiaparampil Atlas of Ultrasound-Guided Procedures in Interventional Pain Management , 2011 .

[12]  Nam-Trung Nguyen,et al.  SU‐8 as a structural material for labs‐on‐chips and microelectromechanical systems , 2007, Electrophoresis.

[13]  B.T. Khuri-Yakub,et al.  Finite-element analysis of capacitive micromachined ultrasonic transducers , 2005, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[14]  Ali H. Nayfeh,et al.  A Reduced-Order Model for Electrically Actuated Clamped Circular Plates , 2003 .

[15]  H. Koymen,et al.  Nonlinear modeling of an immersed transmitting capacitive micromachined ultrasonic transducer for harmonic balance analysis , 2010, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.