A Highly Compact Lensless High-ResolutionA Highly Compact Lensless High Resolution Optofluidic Microscope (OFM)

Xiquan CuiXiquan Cuixiquan@caltech.edu

California Institute of Technology

10μm

Caltech Biophotonics LaboratoryCaltech Biophotonics Laboratory10μm 1

Presented at the evening meeting of theSanta Clara Valley Chapter, CPMT Society, IEEEJanuary 14, 2009 www.cpmt.org/scv/

Redesigning the microscopeRedesigning the microscope

We abandon the conventional microscopy design and uses a novel aperture array for high resolution cell-level imaging.

Images of C. elegans

50 μm

- compact (~ the size of a dime)- potentially cheap ($10’s)potentially cheap ($10 s)

X. Cui et. al, PNAS, 105, 10670 (2008)

Caltech Biophotonics LaboratoryCaltech Biophotonics Laboratory

OverviewOverview

• Motivation• Intensity contrast OFM• Intensity contrast OFM

(a) Gravity driven OFM (GD OFM)- Automated and quantitative OFM microscopy- Phenotype characterization of C. elegans- Resolution issueResolution issue

(b) Electrokinetic OFM (EK OFM)- Spherical/ellipsoidal cells imagingp p g g

• Conclusions and future directions

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Motivation

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Conventional optical microscopyConventional optical microscopy

Advantages:• Noninvasive• Noninvasive• High resolution• Comprehensive microscopy informationComprehensive microscopy information• Gold diagnosis standard

Disadvantages:B lk• Bulky

• Expensive

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Optofluidic microscopyOptofluidic microscopy(OFM)(OFM) y

Microfluidic channel

(OFM)(OFM)CCD or CMOS chip

Opaque layer

xTop view

Hole (A)

ange

s

Slanted nanohole 1D arrayHole (B)

Hole (D)Hole (C)Hole (B)Hole (A)20 µm

mis

sion

chaImprove resolution in both x and y direction

Hole (C)

Tran

sm

Hole (D)

Linear shifting factorFinal !!!

( )

timeNucleated blood cell image is from http://www.wadsworth.org/chemheme/heme/glass/slide_011_nrbc.htm

X. Heng, Lab on a Chip, 6, 1274 (2006)6

Advantages of OFMAdvantages of OFM

• On-chip high resolution imaging• On-chip high resolution imaging- Compact- Low cost

• MicrofluidicsSh j ti- Sharp projection

- Bio-friendly- High efficiency and throughput - Automatic operation

C. elegans images

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Intensity contrast OFM

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Complete onComplete on--chip OFMchip OFM• Small as a dimeSmall as a dime

• High resolution (~1μm)

• Imaging & pump are all - on chip

electrodes

IlluminationSpecimen

IlluminationSpecimen

GoldPMMA

aperture

PDMS

A t

PDMS channel

A t

PDMS channel

G it d i OFM El t ki ti OFM

CMOS Sensor PixelCMOS Chip Packaging

Al layer

CMOS

Flow

Apertures

Al layer

CMOS

Flow

Apertures

Gravity driven OFM

(GD OFM)

Electrokinetic OFM

(EK OFM)

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X. Cui et. al, PNAS, 105, 10670 (2008)

Gravity driven OFM (GD OFM)Gravity driven OFM (GD OFM)

IlluminationSpecimen

IlluminationSpecimen

PDMS PDMS Microfluidic channelchannelchannel

Al layer

CMOS

Flow

Apertures

Al layer

CMOS

Flow

Apertures OFM apertures

Al layer FlowAl layer Flow

• Complete on-chip device

C. elegans flowing in OFM(top view)

Complete on chip device • Self-sustained flow• Bio-compatible

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Automated and quantitative OFM microscopyAutomated and quantitative OFM microscopy

XY vChannel

XY vChannel

SpecimenSpecimen

δY=500nm

L= 9.9μm 1μm

∆X θδY=500nm

L= 9.9μm 1μm

∆X θδY=500nm

L= 9.9μm 1μm

∆X θδY=500nm

L= 9.9μm 1μm

∆X θOFM imagingOFM imagingOFM imaging

δY 500nmδY 500nmδY 500nmδY 500nm

Cross correlation

<50%Cross correlation

<50%<50%

• Automated operation

• Digitized image >50%

Screen out>50%

Screen out

Screen out

Screen out

g g

• Quantitative evaluationAutomatic

measurementAutomatic

measurement

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Resolution comparisonResolution comparisonOFM imaging parameters:• Illumination:

~ 20 mW/cm2 white light,OFM the intensity of sunlight

• CMOS sensor line rate: • 1k fps

Direct sensor

imaging

1k fps• Specimen velocity (V):

~500 μm/s• Sampling grid:(10μm pixel)

20X

• Sampling grid: δX = δY =0.5 μm

• Aperture size (D): NA=0.420X

microscope 1 μm• Microfluidic channel:

width 50 μm, height 15 μmC. elegans

OFM has comparable resolution as a ti l i

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conventional microscope.12

Phenotype characterization of Phenotype characterization of C. C. eleganselegans

Wild t

Performed automated

phenotype characterization

aWild-type

50μm50μm

a) Automated

Dpy 7

b Sma-350μm50μm b) Image 1 worm / 2.5 sec

c) Computerized worm length and area measurement

300d 13e

cDpy-7

50μm50μm

and area measurement

d) Drop and go

100

150

200

250

engt

h (μ

m)

9

10

11

12

Wid

th (μ

m)

0

50

100

Le

7

8

9W

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Resolution Issues Resolution Issues 4

3

4

M ( μ

m)

0.5

1

issi

on (a

.u.)r

Point source

2

on o

f OFM

-5 0 50Tran

smi

r (μm)

HX

Z

Y

1

Res

olut

io

AlSU8

CMOS pixel

10-2 10-1 100 1010

H (μm)

CMOS pixel

Prototype resolution = 0.9 microns (Sparrow’s Criterion)

50μm

15 micron tall channel 25 micron tall channel

Shallow channels give better images.Shallow channels give better images.

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ElectrokineticElectrokinetic OFMOFM ((EKEK OFMOFM))(Collaborated with Lap Man Lee)( p )

electrodesPDMS

illumination

GoldPMMA

aperture

CMOS Sensor PixelCMOS Chip Packaging

• Spherical/ellipsoidal cells imagingSpherical/ellipsoidal cells imaging• Easy to be integrated on a chip

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ElectrokineticElectrokinetic Drive: Why? Drive: Why?

1. EK enables uniform cell transportation.cell transportation.

2. Electroorientationaligns cells.

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OnOn--chip EK OFMchip EK OFM

10μm

OFM

b d f h jb d f h j

conventional microscope

kb d f h

microscope

electrodes

Chlamydomonas mulberry pollen spores

polystyrene microsphere

electrodes

GoldPMMA

PDMS Uniform motions of samples yield perfect EK OFM i

CMOS Sensor PixelCMOS Chip Packaging

aperture OFM images.

CMOS Sensor PixelCMOS Chip Packaging

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Conclusions and future directions

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Conclusions Conclusions

• Created world’s smallest high resolution microscope on a single chipmicroscope on a single chip

• Automated & parallelizable on-chip cell microscopy methodmicroscopy method

• The low cost and compactness of OFM can change the way we use microscopescan change the way we use microscopes

C elegans10μm

10 C. elegansChlamy

10 μm

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AcknowledgmentAcknowledgment

Biophotonics group: Collaborators:Prof. Demetri Psaltis

Prof. Changhuei Yang

Lap Man Lee

Prof. Paul W. SternbergDr. Weiwei ZhongProf. Axel Scherer

F di S

Xin HengMatthew LewDr. Jigang WuD Z hid Y b

Prof. David Erickson (Cornell)Dr. L. Ryan Baugh

Funding Sources:DARPA Center for Optofluidic Integration, NIH

Dr. Zahid YaqoobEmily McDowellHan ShuoG oan Zhang NIH,

Coulter Foundation,Guoan ZhangJian RenDr. Vahan SenekerimyanArthur ChangArthur ChangJose PachecoEdward Hsiao

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Thank you!Thank you!

xiquan@caltech.edu

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