U.S. patent application number 12/755668 was filed with the patent office on 2011-07-14 for novel mems biosensor with integrated impedance and mass-sensing capabilities.
Invention is credited to Muhammad Ibn Ibrahimy, Maizirwan Mel, Anis Nurashikin Nordin, Ioana Rodica Voiculescu.
Application Number | 20110169511 12/755668 |
Document ID | / |
Family ID | 44147744 |
Filed Date | 2011-07-14 |
United States Patent
Application |
20110169511 |
Kind Code |
A1 |
Nordin; Anis Nurashikin ; et
al. |
July 14, 2011 |
NOVEL MEMS BIOSENSOR WITH INTEGRATED IMPEDANCE AND MASS-SENSING
CAPABILITIES
Abstract
A biosensor device (1) providing an analysis platform for
detecting cell growth, comprising of an aluminium nitride (AlN)
base (2), a shear horizontal-surface acoustic wave (SH-SAW)
resonator including an input transducer (4) and an output
transducer (5) symmetrically positioned on the aluminum nitride
(AlN) base (2), a counter electrode (6) positioned parallel to
working electrodes (7) on the aluminum nitride (AlN) base (2), for
transmitting frequency voltage towards the living cell (3), a
plurality of working electrodes (7) positioned beneath the living
cell (3) on the aluminium nitride (AlN) base (2) for receiving
frequency voltage from the living cell (3), an impedance analyzer
(8) for receiving impedance readings from the counter electrode (6)
and working electrodes (7), and a back-etched silicon substrate (9)
coupled to the aluminium nitride (AlN) base (2), for reducing
current loss, wherein the living cell (3) is positioned in between
of the input transducer and output transducer on the aluminium
nitride (AlN) base (4).
Inventors: |
Nordin; Anis Nurashikin;
(Kuala Lumpur, MY) ; Ibrahimy; Muhammad Ibn;
(Kuala Lumpur, MY) ; Mel; Maizirwan; (Kuala
Lumpur, MY) ; Voiculescu; Ioana Rodica; (New York,
NY) |
Family ID: |
44147744 |
Appl. No.: |
12/755668 |
Filed: |
April 7, 2010 |
Current U.S.
Class: |
324/692 |
Current CPC
Class: |
G01N 33/5438 20130101;
Y10T 436/11 20150115; G01N 33/5005 20130101; G01N 33/48728
20130101 |
Class at
Publication: |
324/692 |
International
Class: |
G01R 27/08 20060101
G01R027/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 14, 2010 |
MY |
PI2010000171 |
Claims
1. A biosensor device (1) providing an analysis platform for
detecting cell growth, comprising of: an aluminium nitride (AlN)
base (2) coupled with a piezoelectric thin film; a shear
horizontal-surface acoustic wave (SH-SAW) resonator including an
input transducer (4) and an output transducer (5) symmetrically
positioned on the aluminum nitride (AlN) base (2); a counter
electrode (6) positioned parallel to working electrodes (7) on the
aluminum nitride (AlN) base (2), for transmitting frequency voltage
towards the living cell (3) and is electrically connected to an
impedance analyzer (8); a plurality of working electrodes (7)
positioned beneath the living cell (3) on the aluminium nitride
(AlN) base (2) for receiving frequency voltage from the living cell
(3) and are electrically connected to an impedance analyzer (8); an
impedance analyzer (8) for receiving impedance readings from the
counter electrode (6) and working electrodes (7); and a back-etched
silicon substrate (9) coupled to the aluminium nitride (AlN) base
(2), for reducing current loss; wherein the living cell (3) is
positioned in between the input transducer (4) and output
transducer (5) on the aluminium nitride (AlN) base (2).
2. A biosensor device (1) providing an analysis platform for
detecting cell growth in claim 1 wherein the input transducer (4)
provides means for transmitting shear acoustic wave towards the
living cell (3).
3. A biosensor device (1) providing an analysis platform for
detecting cell growth in claim 1 wherein the output transducer (5)
provides means for receiving shear acoustic wave from the living
cell (3).
4. A biosensor device (1) providing an analysis platform for
detecting cell growth in claim 1 wherein the working electrodes (7)
are gold (Au) electrodes.
5. A biosensor device (1) providing an analysis platform for
detecting cell growth in claim 1 wherein the working electrodes (7)
are covered with cell-extracellular matrix protein (ECM) layer for
facilitating the living cell (3) attachment to these electrodes
array.
6. A biosensor device (1) providing an analysis platform for
detecting cell growth in claim 1 wherein the surface acoustic wave
excitation is preferably at resonant frequency around 100 MHz.
Description
TECHNICAL FIELD
[0001] The present invention relates to a MEMS biosensor device for
providing an analysis platform in detecting cell growth and more
particularly by using shear horizontal-surface acoustic wave
(SH-SAW) resonator and electric cell-substrate impedance sensing
(ECIS) technique.
BACKGROUND ART
[0002] Cancer is the second leading cause of death worldwide. It is
generally agreed that early diagnosis of the disease is almost
always a prerequisite of successful treatment. For decades, cancer
diagnostic methods have been based on morphological examination of
surgically removed tissues. However, this approach has significant
limitations for predicting the progression of the cancer cells such
as inaccuracy and requirement for large amounts of biological
materials. Furthermore, morphological examination of these cancer
cells requires highly trained personnel to be able to distinguish
cancer cells from normal cells. Due to these limitations, a number
of scientists have developed other types of cancer diagnostic
methods, for example a biomarker that uses biological, chemical or
biophysical indicator of an underlying biological process to
indicate or determine a particular disease state. Another method is
by detecting the cell growth using a MEMS (microelectromechanical
system) biosensor device that merges biological knowledge and
microelectronics technology.
[0003] Recently, MEMS technology expands in an extremely fast pace.
It is used in various applications such as actuators,
accelerometer, pressure sensors, chemosensors, gyroscopes, optical
switching technology and more. Nevertheless, MEMS technology is
also used in biological fields for the construction of biosensors.
Generally, a MEMS biosensor is an analytical device with the
combination of biotechnology and microelectromechanical system that
converts a biological response to electrical signal. A MEMS
biosensor can be used as a device to measure chemicals and
micro-organisms in wide range of environments and as a biological
system to detect complex materials. Nowadays, MEMS biosensors have
become widespread use in a wide variety of applications such as
diagnostics, therapeutics and tissue engineering. There are a few
types of biosensor used in the industry such as calorimetric,
potentiometric, amperometric, surface acoustic wave and more. In
calorimetric biosensors, the change in temperature of a solution
containing analyte is measured whereby in potentiometric
biosensors, electrical potential is produced due to the changed
distribution of electrons. As for amperometric biosensors, the
analyte undergoes a redox reaction and the current in an
electrochemical cell. A surface acoustic wave biosensor is a
biosensor based on the measurement of resonant frequency of the
surface acoustic wave. Various types of biosensors have been
developed including the combinations of different types of
biosensors, for example, an amperometric-potentiometric biosensor
that includes both amperometric method and potentiometric method in
detecting cell growth.
[0004] Several prior arts have disclosed applications related to
construction of MEMS biosensors for detecting cell growth. One of
the prior art is U.S. Pat. No. 5,135,852 which discloses a
piezoelectric biosensor for detecting metabolic growth requirement,
antibiotic responses and specific bacterial products of
microorganisms. Generally, the more sensing methods integrated into
a biosensor device enhances the performance of the biosensor
device. However, this prior art utilizes only one type of sensing
method in the biosensor which is a piezoelectric biosensor to
observe the change in resonant frequency in order to detect the
mass change of the living organism. Therefore due to the patent
limited applicability, it is said to be not feasible in
constructing a MEMS biosensor for detecting cell growth.
[0005] U.S. Pat. No. 5,981,268 has disclosed an apparatus and
method for monitoring changes in cells upon addition of an analyte
to the environment of the cell. In this prior art, only one
detecting method is used, which is by monitoring the impedance
changes of the cell, to detect the changes in the cell. This prior
art has its drawbacks due to the limited sensing methods as more
sensing methods can be integrated into one biosensor to monitor the
change of a cell more accurately. Therefore due to the patent
limited applicability, it is said to be not feasible in
constructing a MEMS biosensor for detecting cell growth.
SUMMARY OF THE INVENTION
[0006] In accordance with the present invention, there is provided
a MEMS biosensor device with an analysis platform for detecting
cell growth using two different biosensing techniques. The MEMS
biosensor device is a MEMS (microelectromechanical system)
biosensor that combines microelectronic technology and
biotechnology to obtain information on stiffness and adhesion of
normal and cancer cell. Furthermore, this invention provides
analysis platform for in vitro study and diagnosis of cancer cells.
The two biosensing techniques used in the MEMS biosensor are shear
horizontal-surface acoustic wave (SH-SAW) resonator and electric
cell-substrate impedance sensing (ECIS) technique where the shear
horizontal-surface acoustic wave (SH-SAW) resonator is used to
monitor the resonant frequency of the resonator and the electric
cell-substrate impedance sensing (ECIS) technique is used to record
impedance spectra of different subcellular regions of a single
cell. This biosensor is able to simultaneously perform these two
different types of electric measurements on the same cell in real
time. In this present invention, the preferred embodiment comprises
of an aluminium nitride (AlN) base, a shear horizontal-surface
acoustic wave (SH-SAW) resonator including an input transducer and
an output transducer, a counter electrode, a plurality of working
electrodes, an impedance analyzer and a back-etched silicon
substrate. The aluminium nitride (AlN) base is used to hold the
input transducer, the output transducer, the working electrodes and
the counter electrode, and is coupled to the back-etched silicon
substrate. As for the impedance analyzer, it is electrically
connected to the working electrodes and the counter electrode in
order to record the impedance spectra of the living cell. The shear
horizontal-surface acoustic wave (SH-SAW) resonator having an input
transducer and an output transducer that is symmetrically
positioned on the aluminium nitride (AlN) base, are used
respectively for transmitting surface acoustic wave towards the
living cell and receiving surface acoustic wave from the living
cell. The working electrodes of the electrode cell-substrate
impedance sensing (ECIS) technique are placed on the acoustic path
of the shear horizontal-surface acoustic wave (SH-SAW) resonator
and are used to receive frequency voltage from the living cell. As
for the counter electrode of the electric cell-substrate impedance
sensing (ECIS) technique, it is placed parallel to these working
electrodes and is used for transmitting frequency voltage towards
the living cell. The growth of the living cell can be monitored
through the shift of the resonant frequency from the shear
horizontal-surface acoustic wave (SH-SAW) resonator where the
growth of the living cell changes the parameters of the resonant
frequency. As by using electric cell-substrate impedance sensing
(ECIS) technique, the living cell obstructs the current flowing
from the living cell to the working electrode and therefore causing
an increase in the impedance measurement. By using this MEMS
biosensor, the whole cell can be mapped in terms of cell stiffness,
adhesion and cell viscoelasticity.
[0007] It is a benefit of this present invention to provide a MEMS
biosensor device that uses shear horizontal-surface acoustic wave
(SH-SAW) resonator and electric cell-substrate impedance sensing
(ECIS) technique in detecting cell growth.
[0008] It is another benefit of this present invention to provide a
MEMS biosensor device that is able to perform two different types
of electric measurements simultaneously on the same living cell in
real time.
[0009] It is yet another benefit of this present invention to
provide a MEMS biosensor device that is able to provide information
on the stiffness and adhesion of normal and cancer cell.
[0010] It is further another benefit of this present invention to
provide a MEMS biosensor device that is able to constitute an
analysis platform for in vitro study and diagnosis of cancer
cell.
BRIEF DESCRIPTION OF DRAWINGS
[0011] A complete understanding of the present invention may be
obtained by reference to the accompanying drawing, when considered
in conjunction with the subsequent, detailed description in
which:
[0012] FIGS. 1A and 1B is the top view and side view of the MEMS
biosensor.
[0013] FIG. 2 is the top view of the MEMS biosensor with a living
cell attachment.
[0014] FIG. 3 is the side view of the attachment of the living cell
on the working electrodes.
DETAILED DESCRIPTION OF DRAWINGS
[0015] As required, detailed embodiments of the present invention
are disclosed herein; however, it is to be understood that the
disclosed embodiments are merely exemplary of the invention, which
may be embodied in various forms. Therefore, specific structural
and functional details disclosed herein are not to be interpreted
as limiting, but merely as a basis for the claims. For ease of
reference, common reference numerals will be used throughout the
figures when referring to the same or similar features common to
the figures.
[0016] Referring to FIGS. 1A and 1B, a MEMS biosensor device (1)
comprises of an aluminium nitride (AlN) base (2) coupled with a
piezoelectric thin film, a shear horizontal-surface acoustic wave
(SH-SAW) resonator having an input transducer (4) and an output
transducer (5) that are symmetrically positioned on the aluminium
nitride (AlN) base (2), a counter electrode (6) positioned parallel
to working electrodes (7) on the aluminium nitride (AlN) base (2)
for transmitting frequency voltage towards a living cell (3), a
plurality of working electrodes (7) positioned beneath the living
cell (3) on the aluminium nitride (AlN) base (4) for receiving
frequency voltage from the living cell (3), an impedance analyzer
(8) for receiving impedance readings from the counter electrode (6)
and working electrodes (7), and a back-etched silicon substrate (9)
coupled to the aluminium nitride (AlN) base (2) for reducing
current loss. The aluminium nitride (AlN) base (2) having the
piezoelectric thin film is used to hold the input transducer (4),
the output transducer (5), the counter electrode (6), the working
electrodes (7) and the living cell (3). The piezoelectric thin film
provides an electric field to the aluminium nitride (AlN) base (2)
so that the surface acoustic wave can be transmitted and received
by the input transducer (4) and output transducer (5) respectively.
The aluminium nitride (AlN) base (2) is coupled to a back-etched
silicon substrate (9) in order to reduce current loss. The shear
horizontal-surface acoustic wave (SH-SAW) resonator comprises of
the input transducer (4) and the output transducer (5) where these
input transducer (4) and output transducer (5) are positioned
symmetrically on the aluminium nitride (AlN) base (2). The input
transducer (4) transmits surface acoustic wave with the resonant
frequency around 100 MHz towards the living cell (3) whereby the
output transducer (5) receives the surface acoustic wave from the
living cell (3) in terms of resonant frequency. Shear
horizontal-surface acoustic wave (SH-SAW) resonator is used due to
the minimal damping of the acoustic wave in liquid. The shear
horizontal-surface acoustic wave (SH-SAW) resonator correlates the
relationship between the electrical measurements and mechanical
properties of the living cell (3). The living cell (3) attached
above the working electrodes (7) on the aluminium nitride (AlN)
base (2) with growing activities produces changes in the parameters
of the equivalent circuit that consequently changes the resonant
frequency. As for the electric cell-substrate impedance sensing
(ECIS) technique, it comprises of the counter electrode (6) and the
plurality of working electrodes (7). The working electrodes (7) are
positioned in between the input transducer (4) and the output
transducer (5), and the counter electrode (6) is positioned
parallel to these working electrodes (7) where the counter
electrode (6) is used to transmit frequency voltage towards the
living cell (3) and the working electrodes (7) are used to receive
frequency voltage from the living cell (3). The counter electrode
(6) and the working electrodes (7) are electrically connected to
the impedance analyzer (8) to receive impedance readings from the
counter electrode (6) and working electrodes (7). When the living
cells (3) are placed above the working electrodes (7) on the
aluminium nitride (AlN) base (2), the electrical impedance of the
working electrodes (7) increases due to the fact that more current
has to bypass the living cell (3). With the living cell (3) acting
like an insulating body, the living cell's (3) shape or
fluctuations of the living cell (3) will increase the impedance of
the working electrodes (7). Therefore, impedance measurements can
be performed to monitor the growth of the living cell (3).
[0017] Referring to FIG. 2, it is showing a MEMS biosensor (1)
having the living cell (3) attached above the working electrodes
(7) on the aluminium nitride (AlN) base (2) where the living cell
(3) can be a single normal cell or cancer cell. The working
electrodes (7) are gold electrodes that are patterned in an array
of small electrodes with the dimensions of 2 .mu.m.times.2 .mu.m.
Each of the working electrodes (7) is covered with extracellular
matrix protein layer to promote cell adhesion. The working
electrodes (7) are not in contact with each other. This is to
collect information corresponding to subcellular regions of the
living cell (3). Each working electrode (7) supports a different
subcellular region of the living cell (3), giving information about
the stiffness and attachment of that particular region of the
living cell (3). The impedance measurements are performed using a
small ac electric field over a wide frequency range of 100 Hz to
100 kHz. The impedance analyzer electrically connected to the
counter electrode (6) and working electrodes is used to apply
periodic voltage signals of variable frequency to the counter
electrode (6) and working electrodes (7). The impedance is
calculated as the ration of voltage phasor, U(j.omega.), and the
current phasor, I(j.omega.) as shown in the equation below,
Z ( j .omega. ) = U ( j .omega. ) I ( j .omega. ) = Z re ( .omega.
) + j Z im ( .omega. ) ##EQU00001##
where j= {square root over (-1)}, .omega.=2.pi.f and f is the
excitation frequency in Hz. The magnitude and the phase angle of
the impedance measurement are,
Z = Z re 2 + Z im 2 ##EQU00002## .PHI. = arctan ( Z im Z re )
##EQU00002.2##
[0018] Referring to FIG. 3, it is showing the living cell (3)
attachment on the working electrodes (7) with focal adhesion
contacts and current flowing through the gap (10) between the
living cell (3) and the working electrodes (7). The average gap
(10) between the living cell (3) and the working electrodes (7)
surface is 50 nm to 150 nm. At low frequencies, current flow from
regions beneath the living cell (3) and through the gap (10) with
no change in measured impedance. At moderate frequencies, the
living cell (3) obstructs the current flow and therefore causing an
increase in the impedance measurement.
* * * * *