Combined atomic force microscope and acoustic wave devices: application to electrodeposition.

Combined atomic force microscope and acoustic wave devices: application to electrodeposition.

J.-M. Friedt, L. Francis, K.-H. Choi, F. Frederix and A. Campitelli [email protected] , [email protected]

October 23, 2002

Aim

Development of biosensors based on acoustic wave devices: requires to un- derstand the sensing mechanism in liquid medium.

Biological reactions are too slow: use of electrodeposition (fast, reversible and more reproducible).

Look at the nm scale what is happening and relate the observations to the

frequency variations.

Principle

λ/2

QCM ( =constant) c SAW device ( =constant) λ

k k

QCM: ∆m → ∆λ → ∆f SAW: ∆m → ∆c → ∆Φ → ∆f

)

what about additional viscosity effects ?

Advantages of SAW:

• higher sensitivity (when properly designed)

• open back side for adding more sensing tech- niques

• sensing electrode is not used/polarized

Love mode device:

area (Au) sensing

Quartz (c)

(c’<c)

PDMS flow cell PDMS flow cell

air air

SiO 2

QCM/AFM combination

- static finite element analysis: out of plane displace- ment A is 0.1 pm

- A _dynamic = A _static × Q ⇒ out of plane displacement is 0.3 nm (Q ' 3000)

- in plane displacement is at most 3 nm, smaller than AFM pixel size

- standing wave pattern between QCM and can- tilever holder only disturbs the resonance frequency during approach

- fundamental resonance frequency (5 MHz) is un- stable and overtones of the QCM must be used

O

X Y

Z

MODULEF : friedtj 20/11/01

mail coor sol.b 2862 NOEUDS

9684 FACES 2040 PENTAEDRES 1280 HEXAEDRES OBSERVATEUR SPHERIQUE : 30. 30. 0.29E-01 OUVERTURE : 10.

ISOVALEURS : 20 INCONNUE : 4 MNEMO :PHIE 20 4.9750E-04 19 4.7367E-04 18 4.4735E-04 17 4.2102E-04 16 3.9469E-04 15 3.6837E-04 14 3.4204E-04 13 3.1571E-04 12 2.8939E-04 11 2.6306E-04 10 2.3673E-04 9 2.1041E-04 8 1.8408E-04 7 1.5775E-04 6 1.3143E-04 5 1.0510E-04 4 7.8774E-05 3 5.2448E-05 2 2.6121E-05 1 -2.0539E-07 PEAU + ELIMINATION

DC potential (0.5 V)

O

X Y

Z

MODULEF : friedtj 20/11/01

mail coor sol.b 2862 NOEUDS

9684 FACES 2040 PENTAEDRES 1280 HEXAEDRES OBSERVATEUR SPHERIQUE : 30. 30. 0.29E-01 OUVERTURE : 10.

ISOVALEURS : 20 INCONNUE : 1 MNEMO :VN 20 1.0698E-06 19 1.0177E-06 18 9.6006E-07 17 9.0247E-07 16 8.4488E-07 15 7.8728E-07 14 7.2969E-07 13 6.7210E-07 12 6.1451E-07 11 5.5692E-07 10 4.9932E-07 9 4.4173E-07 8 3.8414E-07 7 3.2655E-07 6 2.6896E-07 5 2.1136E-07 4 1.5377E-07 3 9.6180E-08 2 3.8588E-08 1 -1.9003E-08 PEAU + ELIMINATION

In-plane displacement (1 pm)

O

X Y

Z

MODULEF : friedtj 20/11/01

mail coor sol.b 2862 NOEUDS

9684 FACES 2040 PENTAEDRES 1280 HEXAEDRES OBSERVATEUR SPHERIQUE : 30. 30. 0.29E-01 OUVERTURE : 10.

ISOVALEURS : 20 INCONNUE : 2 MNEMO :VN 20 1.2457E-07 19 1.1232E-07 18 9.8787E-08 17 8.5251E-08 16 7.1715E-08 15 5.8179E-08 14 4.4643E-08 13 3.1107E-08 12 1.7571E-08 11 4.0351E-09 10 -9.5009E-09 9 -2.3037E-08 8 -3.6573E-08 7 -5.0109E-08 6 -6.3645E-08 5 -7.7181E-08 4 -9.0717E-08 3 -1.0425E-07 2 -1.1779E-07 1 -1.3133E-07 PEAU + ELIMINATION

In-plane displacement (0.1 pm)

O

X Y

Z

MODULEF : friedtj 20/11/01

mail coor sol.b 2862 NOEUDS

9684 FACES 2040 PENTAEDRES 1280 HEXAEDRES OBSERVATEUR SPHERIQUE : 30. 30. 0.29E-01 OUVERTURE : 10.

ISOVALEURS : 20 INCONNUE : 3 MNEMO :VN 20 1.0083E-07 19 9.1142E-08 18 8.0432E-08 17 6.9721E-08 16 5.9011E-08 15 4.8301E-08 14 3.7590E-08 13 2.6880E-08 12 1.6170E-08 11 5.4592E-09 10 -5.2511E-09 9 -1.5961E-08 8 -2.6672E-08 7 -3.7382E-08 6 -4.8092E-08 5 -5.8803E-08 4 -6.9513E-08 3 -8.0223E-08 2 -9.0934E-08 1 -1.0164E-07 PEAU + ELIMINATION

Out-of-plane displacements (0.1 pm)

Use of commercial instruments:

- Q-Sense (G¨ oteborg, Sweden) for QCM-D

monitoring (overtones 1, 3, 5, 7+Q factor)

- Molecular Imaging (AZ, USA) AFM

Measurements

100 200 300 400 500 600 700 −0.1 0 0.1 0.2 E (V)

100 200 300 400 500 600 700 −5 0 5 10

(× 10

)

100 200 300 400 500 600 700 −2000 −1000 0

∆f₅

(Hz)

100 200 300 400 500 600 700 −5 0 5

(× 10

)

100 200 300 400 500 600 700 −1500 −1000 −500 0 500

∆f₃

(Hz)

100 200 300 400 500 600 700 −200 0 200 d/dt(∆f

), i

i*2.5.10

−100 d/dt(<

f

>

)

Ag

100 200 300 400 500 600 700 −40 −20 0 20 d/dt(∆f

), i

100 200 300 400 500 600 700 −0.2 0 0.2 0.4 E (V)

100 200 300 400 500 600 700 −10 0 10 20

(× 10

)

100 200 300 400 500 600 700 −2000 −1000 0

∆f₅

(Hz)

100 200 300 400 500 600 700 −20 0 20 40 60

(× 10

)

100 200 300 400 500 600 700 −2000 −1000 0

∆f₃

(Hz)

i*10

−20 d/dt(<

f

>

)

Cu

Rigid layer ⇒ ∆f _n /n ∝ ∆m _layer (low damping) with n: overtone number Viscous layer ⇒ ∆f _n / √

n ∝ { ∆m _liquid , ∆m _layer } (large damping)

(15 MHz)

Z =9420 Ω

viton O−ring teflon liquid cell

QCM AFM cantilever

glass prism laser beam photodetector

measurement setup

Gamry potentiostat (WE) Q−Sense QCM parameters

L=100 H µ

(25 MHz)

(15 MHz)

Z =6

Ω Z =15708 Pt (CE)

(RE)

1 nF

(15 MHz)

Z =11 Ω

Ω

Experimental setup

Φ G Network

analyzer

∆Φ , IL

−6 −4 −2 0 2 4 6

x 10 ⁵

−45

−44

−43

−42

−41

−40

−39

−38

−37

I.L. (dB)

∆ f (f ₀ −124.4 MHz)

−6 −4 −2 0 2 4 6

x 10 ⁵

−150

−100

−50 0 50 100 150

Φ ( o )

∆ f (f ₀ −124.4 MHz)

slope: 360 ^o /601.38 kHz

⇔ 1670 Hz/ ^o

Closed loop monitoring

frequency Open loop monitoring

Open/closed loop operation:

requires a 4-port network analyzer

PLL setup: compensate for energy losses (and phase shift)

Problem: liquid must not

reach the IDTs

Measurements

2 4 6 8 10 12

x 10 ⁴

−1 0 1

E(V)

device 11 (1.38 µm SiO ₂ ), 10 ⁻² CuSO ₄ , 10 ⁻² H ₂ SO ₄

2 4 6 8 10 12

x 10 ⁴ 123.62

123.64 123.66 123.68 123.7

f (MHz)

2 4 6 8 10 12

x 10 ⁴

−1 0 1

I (mA)

−→ time (a.u.)

m _Cu =

P I × δt

N × e × ^M _n ^Cu _e

N × e = 96440 C: 1 Faraday M _Cu = 63.5 g/mol, n _e = 2

1 1.05 1.1 1.15 1.2 1.25 1.3 1.35

x 10 ⁵

−1 0 1

E(V)

device 11 (1.38 µm SiO ₂ ), 10 ⁻² CuSO ₄ , 10 ⁻² H ₂ SO ₄

1 1.05 1.1 1.15 1.2 1.25 1.3 1.35

x 10 ⁵ 123.62

123.64 123.66 123.68 123.7

f (MHz)

1 1.05 1.1 1.15 1.2 1.25 1.3 1.35

x 10 ⁵

−1 0 1

I (mA)

Sensitivity estimates

0 100 200 300 400 500 600 700 800 900 1000

0 10 20 30 40 50 60 70 80 90 100 110

mass (ng, estimated from electrochemistry)

sensitivity (cm 2 /g): S=(A ×∆ f)/(f 0 ∆ m) Love mode: 1.38 µm SiO ₂

Love mode: 2.96 µm SiO ₂

QCM (Sauerbrey, 5 MHz): S ∼11 QCM (Sauerbrey, 10 MHz): S ∼23 S→102

S→58

S = ^{∆ f}

f ₀ × _∆ ^A _m ^{cm 2 /g}

A: sensing area (3.2 × 3.5 mm ² ) f ₀ : center frequency (123.7 MHz)

∆m: deposited mass (electro- chemistry)

∆f : frequency variation

S assumed to be constant, ∀ ∆m. Good fit when including offset in the

current measurement by the potentiostat ⇒ rigid mass.

AFM combination

Monitoring simultaneously ∆Φ ⇒ ∆f , ∆m and topography at the nm scale

⇒ S ' 70..80 for ∆m = 4.5..7.5 µg (S _QCM ' 20 cm ² /g).

Conclusion and perspectives

• ability to independently measure deposited mass and frequency shift

• estimation of the sensitivity: constant over the mass range analyzed

• high sensitivity of Love mode device ( ∼ 10 times more sensitive than QCM)

- fluidics setup (IDTs protection)

- application to biology: replace electrochemical cell by biochemical reactions - combination with other detection methods (SPR)

Copies of the slides at http://mmyotte.free.fr/chua