cmos microelectrode array for monitoring electrogenic cells
TRANSCRIPT
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CMOS MICROELECTRODE ARRAY
FOR MONITORING ELECTROGENIC
CELLSPRESENTED BY,RENIT RAGHAVAN
S7 EC
ROLL NO:44
INTERNAL GUIDE:REMYA RAMESH
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OVERVIEW
´ Introduction´ History
´ Electrogenic cells
´ Why CMOS?
´ System architecture
´ Application
´ Advantages
´
Future enhancement´ Conclusion
´ Reference
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INTRODUCTION
´ Its a new biochip consisting of an array of
microelectrodes with fully integrated analog
and digital circuitry
´ CMOS MEAs are used for the stimulation and
recording of activity from electrogenic cells
´ Its generally a metallic electrode with similar
diameter as the cell
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HISTORY
´Recording electrical oscillations in the brainbegan in 1875
´ Traditional methods include patch clamp and
voltage-sensitive dyes
´MEAs was discovered in the early 1970s bywise and thomas
´ In the year 2001 single chip solutions withfully-integrated CMOS multiplexing andbuffering circuitry was presented
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ELECTROGENIC CELLS
´ Cells that exhibit the ability to become
electrically active are called electrogenic cells.
´
Cardiomyocyte (heart cells) or neurons (braincells) are examples of electrogenic cells
´ They rely on electric signals to communicate
with each other
´ They have the ability to produce voltage
changes called action potentials
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ELECTROGENIC CELLS
´ Biochemical processes in vertebrates arebased on the activity of these cells
´ Diseases based on malfunction of
electrogenic cells are among the most serioushealth problems
´ The cell activity can be measured
extracellularly by using a microelectrode
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ELECTROGENIC CELLSMAMMALIAN NEURONS
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ELECTROGENIC CELLS
cardiomyocytes(heart cells) or neurons(brain cells)
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WHY CMOS?
´ Complementary metal-oxide-semiconductor(CMOS) is a technology for constructing
integrated circuits
´ High noise immunity and low static powerconsumption
´ It offers some decisive advantages, in
particular multiplexers and on-chip electronics
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CMOS CHIP
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MEA(MICROELECTRODE ARRAY)
´ In a MEA, numerous electrodes are arranged
in an array on a planar substrate
´
Neural signals are delivered or obtainedthrough MEA
´ Neurons and muscle cells create ion currents
through their membranes when excited
´ When recording, the electrodes on an MEA
transduce the change in voltage
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VITRO MEA
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CMOS MEA¶S
´MEAs fabricated in CMOS are called CMOS
MEAs
´
The use of CMOS electronics overcomes thedrawbacks of traditional MEAs
´ CMOS electronics offer on-chip multiplexers
´ It has MOS switches, which allow to use the
electrode for both, recording and stimulation
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S YSTEM ARCHITECTURE
´ The chip size is 6.5mm by 6.5mm
´ It consists of 128 electrodes in an 8x16 array
´ The pitch of the pixel unit is 250 micro meter
´ A digital control unit is integrated on the chip
´ It consists of 16 ADC and a DAC
´ An on-chip temperature sensor monitors the
chip operating temperature
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MICROGRAPH OF CMOS MEA
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SYSTEM ARCHITECTURE
´ Action potential in an electrogenic cell causes
ion flow across the cell membrane
´
This induce charges on the metal electrode´ Offsets of the electrode potential of up to 1 V
and drifts of up to 100 mV within a few
seconds have been measured
´ A high-pass filter has been used as the first
read-out stage
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SYSTEM ARCHITECTURE
´ The signals then pass a low-pass filter with a
corner frequency of about 5 kHz to prevent
high-frequency aliasing
´ Finally, a buffer with a larger bandwidth has
been realized to further amplify the signal and
to allow for multiplexing
´ To achieve good signal-to-noise ratio, an 8-bit
A/D converters has been used
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RESULTS
Neural spike recording using cmos-mea
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APPLICATION
´MEA finds a multitude of applications in both
applied and pure science
´ It is used to study about brain
´ Used for the detection of chemical and
biological toxins
´ To study about health problems
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FUTURE ENH ANCEMENT
´ An MEA with more number of electrodes
´ Integration of more sensors
´
Use of stimulation buffer
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CONCLUSION
´ CMOS MEA is a monolithic extracellular
recoding system
´ A new technology for the neuroscientist
´ Viable approach to recover skeletal muscle
function and to restore visual perception
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ADVANTAGES
´ CMOS MEA include multiplexers and on chip
electronics
´ Improved signal to noise ratio
´ Low power consumption
´ On-chip A/D and D/A conversion
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REFERENCE
´ Bates, J.B., Chu, Y.T., 1992. Electrode²
electrolyte interface impedance:experiments
and model. Ann. Biomed. Eng. 20 (3), 349²
362.´Maher, M.P., Pine, J., Wright, J., Yu Chong, T.,
1999. The neurochip: a new multielectrode
device for stimulating and recording fromcultured neurons
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