A silicon MEMS structure for characterization of femto-farad-level capacitive sensors with lock-in architecture

This paper presents a silicon MEMS capacitive structure to investigate a test methodology for fF-level capacitive sensors’ measurement. The device mimics a capacitive sensor with a changing intermediate layer between the electrodes. A single mask bulk micromachining process is used to fabricate the device, which has a nominal capacitance of 1.2 fF. A high performance measurement setup based on lock-in principle is developed to detect the capacitance variation. The maximum capacitance variation of the fabricated device is 0.31 fF, and the capacitance detection limit is 0.095 aF Hz?1/2.

[1]  N. Yazdi,et al.  Precision readout circuits for capacitive microaccelerometers , 2004, Proceedings of IEEE Sensors, 2004..

[2]  Rahul Sarpeshkar,et al.  An offset-canceling low-noise lock-in architecture for capacitive sensing , 2003, IEEE J. Solid State Circuits.

[3]  Kimberly L. Turner,et al.  SCREAM’03: A Single Mask Process for High-Q Single Crystal Silicon MEMS , 2004 .

[4]  Willy Sansen,et al.  Analog circuit design : RF analog-to-digital converters; sensor and actuator interfaces; low-noise oscillators, PLLs and synthesizers , 1997 .

[5]  Y. Tai,et al.  Surface micromachined and integrated capacitive sensors for microfluidic applications , 2003, TRANSDUCERS '03. 12th International Conference on Solid-State Sensors, Actuators and Microsystems. Digest of Technical Papers (Cat. No.03TH8664).

[6]  Jun Guo,et al.  A High-Performance MEMS Capacitive Strain Sensing System , 2006, Journal of Microelectromechanical Systems.

[7]  Emilio Sardini,et al.  Measurement of small capacitance variations , 1990 .

[8]  P.M. Sarro,et al.  Characterization of a Nozzle-Integrated Capacitive Sensor for Microfluidic Jet Systems , 2007, 2007 IEEE Sensors.

[9]  Bernhard E. Boser,et al.  Capacitive Interfaces for Monolithic Integrated Sensors , 1997 .

[10]  Bernhard E. Boser,et al.  A three-axis micromachined accelerometer with a CMOS position-sense interface and digital offset-trim electronics , 1999, IEEE J. Solid State Circuits.

[11]  Kofi A. A. Makinwa,et al.  Implementation and Characterization of a femto-Farad Capacitive Sensor for pico-Liter Liquid Monitoring , 2009 .

[12]  Joan Carletta,et al.  A micromachined high throughput Coulter counter for bioparticle detection and counting , 2007 .