04-06-2012, 12:53 PM
Ultrahigh-Sensitivity Pressure and Vibration Sensor
[attachment=24125]
I. INTRODUCTION
RECENT trends in earthquake monitoring and prediction
have created a requirement for a highly sensitive vibration
detector (e.g., detector with sensitivity for accelerations of
less than g) [1]–[6]. In addition, a highly sensitive pressure
sensor (a sensor with a capability to detect pressures of less
than one Pascal) will be very useful for a new class of biological
and molecular sensing applications [7], [8]. It has recently
been demonstrated that sensors based on variable capacitance
can offer the highest sensitivity among all known types of pressure/
vibration sensing mechanisms [9]–[13]. However, capacitive
pressure/vibration sensors still cannot offer the ultrahigh
sensitivity that is needed for demanding applications such as
earthquake prediction and the detection of very small pressures
in biological processes. It is the objective of this paper to introduce
a new sensor with such ultrahigh sensitivity.
The basic idea behind the new sensor is to create a transduction
mechanism that uses a variable ultracapacitor rather than a
variable capacitor. In this mechanism, an extremely small displacement
of 20 m (less than the width of a human hair) triggers
a substantially large variation in capacitance. This concept
is shown in Fig. 1.
Manuscript received February 25, 2011; revised April 08, 2011; accepted
May 09, 2011. Date of publication May 19, 2011; date of current version
November 02, 2011. The associate editor coordinating the review of this
manuscript and approving it for publication was Dr. Subhas Mukhopadhyay.
E. G. Bakhoum is with the Department of Electrical and Computer Engineering,
University of West Florida, Pensacola, FL 32514 USA (e-mail:
ebakhoum[at]uwf.edu).
M. H. M. Cheng is with the Department of Mechanical and Aerospace Engineering,
West Virginia University, Morgantown, WV 26506 USA (e-mail:
Marvin.Cheng[at]mail.wvu.edu).
Color versions of one or more of the figures in this paper are available online
at http://ieeexplore.ieee.org.
Digital Object Identifier 10.1109/JSEN.2011.2155646
Fig. 1. Fundamental concept of the new ultrahigh-sensitivity pressure/vibration
sensor. (a) An ultracapacitor consisting of two electrodes is assembled such
that one electrode is fixed and is fully immersed in the electrolyte while the other
electrode is movable and is initially positioned outside of the electrolytic solution.
Each electrode consists of a stainless-steel plate on which carbon nanotubes
of a length of approximately 20
[attachment=24125]
I. INTRODUCTION
RECENT trends in earthquake monitoring and prediction
have created a requirement for a highly sensitive vibration
detector (e.g., detector with sensitivity for accelerations of
less than g) [1]–[6]. In addition, a highly sensitive pressure
sensor (a sensor with a capability to detect pressures of less
than one Pascal) will be very useful for a new class of biological
and molecular sensing applications [7], [8]. It has recently
been demonstrated that sensors based on variable capacitance
can offer the highest sensitivity among all known types of pressure/
vibration sensing mechanisms [9]–[13]. However, capacitive
pressure/vibration sensors still cannot offer the ultrahigh
sensitivity that is needed for demanding applications such as
earthquake prediction and the detection of very small pressures
in biological processes. It is the objective of this paper to introduce
a new sensor with such ultrahigh sensitivity.
The basic idea behind the new sensor is to create a transduction
mechanism that uses a variable ultracapacitor rather than a
variable capacitor. In this mechanism, an extremely small displacement
of 20 m (less than the width of a human hair) triggers
a substantially large variation in capacitance. This concept
is shown in Fig. 1.
Manuscript received February 25, 2011; revised April 08, 2011; accepted
May 09, 2011. Date of publication May 19, 2011; date of current version
November 02, 2011. The associate editor coordinating the review of this
manuscript and approving it for publication was Dr. Subhas Mukhopadhyay.
E. G. Bakhoum is with the Department of Electrical and Computer Engineering,
University of West Florida, Pensacola, FL 32514 USA (e-mail:
ebakhoum[at]uwf.edu).
M. H. M. Cheng is with the Department of Mechanical and Aerospace Engineering,
West Virginia University, Morgantown, WV 26506 USA (e-mail:
Marvin.Cheng[at]mail.wvu.edu).
Color versions of one or more of the figures in this paper are available online
at http://ieeexplore.ieee.org.
Digital Object Identifier 10.1109/JSEN.2011.2155646
Fig. 1. Fundamental concept of the new ultrahigh-sensitivity pressure/vibration
sensor. (a) An ultracapacitor consisting of two electrodes is assembled such
that one electrode is fixed and is fully immersed in the electrolyte while the other
electrode is movable and is initially positioned outside of the electrolytic solution.
Each electrode consists of a stainless-steel plate on which carbon nanotubes
of a length of approximately 20