Dominik Ziegler PhD

Material Science Division, Molecular Foundry, Lawrence Berkeley National Laboratory

ENCASED CANTILEVERS FOR LOW-NOISE FORCE

AND MASS SENSING IN LIQUIDS

Dominik Ziegler PhD

Material Science Division, Molecular Foundry, Lawrence Berkeley National Laboratory

Quantitative Mass Sensor

Gentle Imaging of

Lipid Bilayers

Encased Cantilevers

Fabrication

High Resolution

Imaging of Mica

Interferometric

Deflection Detection

TbkQ

TkkF B

i

Bn 4

4

0

VISCOUS DAMPING LIMITS RESOLUTION

ω0≈150 kHz

Q≈200

ω0≈50 kHz

Q≈4

100 m long, 30 m wide

Fn air≈15fN/√Hz

Fn water ≈200fN/√Hz

Force Noise Smallest Measurable Force

High forces deform soft samples and limits resolution

LET`S GO SCUBA DIVING!

FABRICATION OF ENCASED CANTILEVERS

-Length of levers can be tuned

-Tip’s sharpness is maintained

FABRICATION OF ENCASED CANTILEVERS

-Length of levers can be tuned

-Tip’s sharpness is maintained

ENCASED CANTILEVER IN AIR/WATER

air

water

fair=310.280kHz

fwater=309.71kHz

Qair=210

Qwater=133

Single clean resonance peak.

High Q and high frequency, performance as in air (Fn=12 fN/sqrt(Hz))

-Only small frequency shift (1%) No Added Mass

-Viscous damping of tip (few um) and double sided squeeze film damping

GENTLE IMAGING OF LIPID BILAYERS

height of supported DPPC

bilayers on mica

softest possible imaging

amplitude modulation

Thicker measured height Less deformation by tip

“Hydra Levers” by AppNano

L = 200 µm, k=0.084N/m f=17 kHzEncased silicon lever (Mikromasch NSC36)

l =110 µm, k = 0.95N/m, f=85kHz

HIGH-RESOLUTION IMAGING OF MICA IN LIQUID

MICA lattice using amplitude modulation

300mM KCl, 10mM K2HPO4, 5 lines/s

Unmodified commercial instrument

Multimode, Bruker

0.5 nm

3210

20

15

10

5

0

[nm]

Am

pli

tud

e[m

V]

3210

60

40

20

0

-20

[nm]

Ph

ase

[Deg

]OSCILLATORY HYDRATION FORCE

(WATER STRUCTURE ON MICA)

~4Å

Kobayashi, J. CHEM. PHYS. 138, 184704 (2013)

Phase [

Deg]

Am

plit

ude [

Å]

0.5 nm

Ultra-small amplitude displacement of the last few water layers

single curve no averaging

QUANTITATIVE MASS SENSING WITH ENCASED CANTILEVERS

Indirect measurement of mass over

surface stress (DC measurement)

Known location of added mass quantitative mass sensor

0

2

4

8

16

30252015105

Time [s]

mc = 22.88ng ne =1

(biL)4=

1

Ci4

» 0.23

QUANTITATIVE MASS SENSING WITH ENCASED CANTILEVERS

Known location of added mass quantitative mass sensor

Rp = -14.8mHz/fg

250 nm Gold Particles

Theory Gold Sphere

m=157 fgCantilever Based Mass Sensing

mavg= 168 ± 12 fgTEM Based Estimation

mavg= 175 ± 68 fg

Rp = -14.8mHz/fg

mc = 22.88ng ne =1

(biL)4=

1

Ci4

» 0.23

QUANTITATIVE MASS SENSING WITH ENCASED CANTILEVERS

250 nm Gold Particles

l =125mm

w = 30mm

h = 2.5mm 317

220

10

0

Q

kHz

mNk

dm = 0.1 fg / Hz » 60MDa / Hz

A=100nm

l = 25mm

w = 5mm

h = 5mm

k =1700N m

w0 =11.0MHz

Q = 4500

Optimized for Mass Sensing

A=100nm

dm = 20zg / Hz »12.5kDa / Hz

Current Cantilever Design

~60 Gold Atoms

Each 0.32 zg

SMALLEST DETECTABLE MASS

Single Very Small Protein

(~100 Carbon-12 Atoms)

l =125mm

w = 30mm

h = 2.5mm 317

220

10

0

Q

kHz

mNk

dm = 0.1 fg / Hz » 60MDa / Hz

A=100nm

l = 25mm

w = 5mm

h = 5mm

k =1700N m

w0 =11.0MHz

Q = 4500

Optimized for Mass Sensing

A=100nm

dm = 20zg / Hz »12.5kDa / Hz

Current Cantilever Design

~60 Gold Atoms

Each 0.32 zg

SMALLEST DETECTABLE MASS

Single Very Small Protein

(~100 Carbon-12 Atoms)

INTERFEROMETRIC READOUTDestructive interference if path length difference (δ) between two

beams is

Finesse F= δλ/Δλ

Detect intensity of reflected light

(Single photodiode, high BW 50MHz)

F=δλ/Δλ

k=45N/m

f0=320kHz

Finesse ~3

Position Noise ~6fm/√Hz! (@10.6mW,~770nm)

Encased cantilevers overcome the problem of

viscous damping in liquids

Compatible with commercial instruments

-Ultra-low force noise in liquids 12 fN/sqrt(Hz)

-Gentle and High-Resolution Imaging

-Water Hydration Layers

-Quantitative Mass Sensor 0.1 fg/sqrt(Hz)

-Interferometric Readout 6 fm/sqrt(Hz)

CONCLUSION

ACKNOWLEDGEMENTS

National Science Foundation

Cyber-enabled Discovery and Innovation #CBET-

940417

US Department of Energy DOE

#DE-AC02-05CH11231

www.foundry.lbl.gov www.scubaprobe.com www.lbl.gov

Paul D Ashby

Technical Support

Ed Wong, Virginia Altoe

Modeling of Squeeze Film Damping

Dara Badri (UC Berkeley)

Aram Klaassen (University of Twente, The Netherlands)

Frieder Muegele (University of Twente, The Netherlands)

John Sader (University of Melbourne, Australia)

For more information please contact Dominik Ziegler PhD, dziegler@lbl.gov, +1 510 599 4444

Interferometric Readout

Adrian Nievergelt (EPFL, Switzerland)

Preparation of Lipid Bilayers

David Chmielewski (UC Berkeley)