a novel plug n play mems-based dna microarray · a novel plug n play mems-based dna microarray k....

A Novel Plug n Play MEMS-Based DNA Microarray

K. Jindal, V. Grover, B. Nayak

Birla Institute of Technology and Science, Pilani, India

A typical microarray experiment

• Microarrays are used to determine expression levels of thousands of genes in a sample of cells at once.


RNA DNA


RNA DNA

DNA Fluorescence Electrical Signal


RNA DNA

DNA Electrical Signal

MEMS based DNA microarray

Geometry of the sensor

• Clamped-clamped beamwhich acts as a resonantmass sensor.

• The base is made of silicon, apiezoelectric layer of PZT atopthe base and a patch of silicaon the top.

• Capacitive actuation; bottomface grounded and electrodeplaced a certain distancebelow it.

Component Dimensions (l x b x h) (um)

Silicon Base 40 x 10 x 2

Piezoelectric Transducer(PZT)

40 x 10 x 0.1

Silica Patch 5 x 5 x 0.1

Design of Actuation Circuit

• When an AC voltage is applied on the electrode, the force on theground plate varies sinusoidally, hence leading to vibration of thesensor.

• Actuation circuit was designed so that the sensor gives an output of~100µV peak to peak at resonance.

dGround

Electrode

DC pre-stressing voltage: 40V

AC actuating voltage: 1V

Design of Actuation Circuit

Plate separation obtained: 286nm

𝑉𝑠𝑒𝑛𝑠𝑜𝑟 =𝑑31𝑌𝑏

𝐶 𝑙

𝜀1𝑑𝑥

𝜀1 =3𝐹

𝑌𝑏𝐻21 −

𝑥

𝑙

𝐹 =𝜀0𝐴𝑉𝐴𝐶𝑉𝐷𝐶

𝑑2

Peak voltageacross sensor

Plateseparation

Damping

• Rayleigh damping model was assumed and damping coefficients were calculated using the following equation:

1/4𝜋𝑓1 𝜋𝑓11/4𝜋𝑓2 𝜋𝑓2

𝛼𝛽 =

𝜉1𝜉2

• α = 53615.8643 1/s

• Β = 1.2275e-11 s

Resonant frequency-mass relation

𝑤ℎ𝑒𝑟𝑒

• The new resonance frequency can be found out in terms of the existing resonance frequency and change in mass as:

Simulation results

(a) (b)

(c) (d)

Simulation results

1.04E+07

1.04E+07

1.04E+07

1.04E+07

1.04E+07

1.04E+07

1.04E+07

1.04E+07

1.04E+07

1.04E+07

4.05E-16 1.25E-15 2.09E-15 2.93E-15 3.77E-15 4.62E-15

RES

ON

AN

T FR

EQU

ENC

Y (

HZ)

MASS ON CANTILEVER (KG)

Electronic Circuit

SENSOR OUTPUT CHARGE AMPLIFIER OUTPUT STAGE

Electronic Circuit Bode plot

Magnitude: 20dB Phase: -110o

Conclusion

• The study demonstrates simulation of a functioning linear MEMS based DNA sensor with tunable sensitivity.

• We feel that such a device, if implemented successfully would be very useful in making microarray technology available to a wider group of researchers.

Thank You

Questions?

a novel plug n play mems-based dna microarray · a novel plug n play mems-based dna microarray k....

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