koc university moems for display, spectroscopy and imaging applications hakan urey koç university...

Koc University

MOEMS for Display, Spectroscopy and Imaging Applications

Hakan Urey

Koç University – Istanbul, TURKEY

http://mems.ku.edu.trEPFL Seminars (Neuchatel and Lausanne)

Feb 5-6, 2009

Koc University

Hakan Urey, Koc University-Istanbul

2

Koç University• Private University established by Vehbi Koç Foundation• ~3,500 undergraduate and 400 MS and PhD students.• Established in 1993; College of Engineering in 2001• Among the top Universities in Turkey based on scholarly

research articles and faculty awards

Koc University


3

Prof. Hakan Ürey (Director)Dr. V.C. Kishore (Post-doc)Sven Holmström

(Researcher) Selim Ölçer (Technician)

Graduate StudentsOnur FerhanogluAslıhan ArslanHuseyin R. SerenErdem ErdenGökhan HatipoğluS. Kutal GökçeDuygu Kutluoğlu (KU-EPFL)Ersin Huseyinoglu

Undergraduate AssistantsUtku BaranErman TimurdoğanÖzge TekinBaran GözcüÖzerk MemişF. Firat Gonen

Research Focus: • Micro-optics, • MEMS/NEMS sensors and actuators, • 2D/3D Display and Imaging Systems

Koc University


4Outline: OML Research Projects

Brief Overview of:

MOEMS thermal sensor array

3D Displays Not MEMS

Part 1: Electro-Magnetic Actuated Systems:

Pico projectors and 2D MEMS scanner (Lorentz Force)

FR4 scanners for imaging (Moving magnet)

MOEMS biosensors (Thin Ferromagnetic Film)

Part 2: Comb-drive Electrostatic Actuated Systems:

MOEMS Fourier transform spectrometers

Scanned Imaging using MEMS Stages and Microlens Arrays

Koc University


5

OML Research Projects: MOEMS Thermal Imaging Sensor Array

Bimaterial Legs

1st order

-1st order

0th order

IR

Diffraction Grating

readoutlaser

IR

0 0.2 0.4 0.6 0.8 10

0.2

0.4

0.6

0.8

1

ratio of gap to the wavelength

norm

alized inte

nsitie

s in t

he o

rders

0th

1st

Inte

nsi

ty

Gap / wavelength

Licensed to ASELSAN, TR

JAP 2006; PTL 2008; Sens&Act 2009

Advantages - Eliminates the need for electrical connection- Interferometric sensitivityRecent collaboration with EPFL (Prof. Leblebici)

Koc University


6

Two-wavelength Interferometry for Extended Range Imaging with Grating Interferometry

λ1

λ2

λ1 & λ2

PD2

PD1

g

O. Ferhanoglu, F. Toy, H. Urey, PTL 2007

Unambigious detectionFull range

Koc University


7

RB

G

Multi-viewer 3D display technology

Sponsors: TUBITAK; FP6 3DTV

Novel 3D display technology Scanning LED Array on FR4 platform

Sponsor: EC FP7-STREPHELIUM3D

OML Research Projects:3D Display Development Projects

Light engine module of the 3D display system

Koc University

EM Actuated Devices

MEMS Scanners Display

FR4 Scanners Imaging

Ni Cantilever Resonators Biosensor

Koc University


9Needs a MEMS Scanner

• Case for a scanning mirror & laser light– Together they address all the critical properties

• Small size• Low power• Bright

Single Mirrorscanner

Imageplane

Light source

Koc University


10Microvision PicoP – MEMS Inside

Integrated Photonics Module (IPM)Including 2D MEMS scanner and

modulated RGB Laser diodes

CES2007

Microvision Inc.

2D MEMS Scanner

CES2008

Koc University


11

2D MEMS Scanner with Single Coil Magnetic Actuation

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

Vertical Scan Flexures (60 Hz)

Horizontal Scan Flexures (20 KHz) Portion of 2D Raster Pattern

for SVGA Display

• Coil current carries excitation signals for both axis:

(60Hz sawtooth + 20KHz sine)

Drive coil

Koc University


12Microfabrication

• 300um Silicon wafer• Structure formed with DRIE• Front Side:

– Electroplated multi-turn coils – PZR sensors on both flexures– Al mirror

• Backside KOH etched to reduce weight

Integrated PZR Angle Sensor Packaged Device (no vacuum)Includes magnet under Si die

Si Die

R. Sprague et al Proc. SPIE Vol. 5721, pp. 1-13 (2005); Urey et al, Optical MEMS 2006; Yalcinkaya et al, JMEMS (2006)

Koc University


13

Summary: MEMS Scanner Performance Comparison

SXGA(1280x1024)

0 5000 10000 15000 20000 25000 30000 35000

op

tD (

de

g.m

m)

-

Frequency(Hz)

DickensheetsMiyajima (99)Hofmann (99)

Schweizer (2000)

Lakner(99)Schenk(

Thesis,2000Schenk(2000)Type 1

Wine (2000)Nomad Spec.Urey (steel) (2002) Schenk(2000

QVGA(320x240)

VGA(640x480)

SVGA(800x600)

16

Dickensheets (97)

Miyajima (2004)Torashima (2004)

Schweizer (2000)

Schenk(2001)

Schenk(2000) Wine (2000)

Ko (2004)Urey (2002)

Microvision NOMAD

Steelscanner

Tani (2004)Hilhol (2004)

Urey (2004)

8

24

32

40

48

56

64

72

80

88

96

104

This Work (2005)

2D BimagneticMEMSScanner

Yalcinkaya, Urey, Montague, Brown, Sprague, JMEMS (2006)

HorizontalResolution

VerticalResolution

Koc University


14

• Silicon MEMS scanners work great but making really low-cost and low-frequency devices proved to be difficult with Silicon!

“In the middle of difficulty lies great opportunity”

– Albert Einstein

Koc University

FR4 Scanners

Koc University


16

FR4 as an Opto-Electro-Mechanical Platform

Standard PCB technology Excellent electrical, mechanical, and thermal properties Different structural thicknesses: 130um, 200um, 250um, 300um…1.5mm Highly integrated, flexible, robust, low-cost

FR4

FR4 sandwiched between copper laminates

Koc University


17

High Degree of Integration on mm/cm-sized FR4 Platform (not

possible with MEMS)

Fresnel lens and curved mirror on FR4 for imaging

LED and waveguide on FR4 (displays / optical interconnects)

LED array and focusing leng on FR4(Module for a 3D display)

Integrated module with optics, IC, optoelectronics, 2 DOF scanning

Koc University


18

Moving Coil with Lorentz Force Actuation

I

FR4 scanner and coil

Urey et al, PTL 2008

5mm x 5mm

Electrical vias

FR4 substrate

Double-sided Cu coils

Mirror attached on one side

Typically < 200Hz operation

Koc University


19

FR4 Applications: Imaging with Dynamic Focusing

Moving LD mounted on FR4

LD

LD

75 mm

650 mm

500 um

500 um displacement of the laser diode results in about 600mm displacement of the focused spot position

Can think of as either auto-focus OR x-z scanning device

f = 6 mm

Koc University


20

FR4 Laser Scanner with Dynamic Focusing Experimental Results -

0

100

200

300

400

500

600

50 150 250 350 450 550 650 750 850 950

Distance from Scanner [mm]

FW

HM

Sp

ot

Siz

e [u

m]

6.5mm6.3mm6.2mm6.1mm6mm6.03mm

As the spot is focused further away, spot size gets bigger, DOF gets longer

500um plunger displacement shifts the beam waist location from 70mm to almost 700mm

Isikman, et al, PTL 2009

Koc University


21

FR4 and Silicon Technology Comparison for EM Actuators

FR4 Silicon

Fabrication Technology Standard PCB MEMS

Density [kg/m^3] 1860 2300

Density of copper 8960 8960

Young's Modulus [Gpa] 10-20 168

Torsional Modulus [Gpa] 2-5 51

Min Coil Trace Width / Spacing100um

10um

Min Via Hole Size

350um (25um with laser)

Min feature size

100um (drill); 20um laser (5um in 2009)

2um (lithography)

Copper thickness 30um 10um

Number of Coil layers 2 - 20 1

Resistance / Power Low High

difficult

Koc University

Type 3: Thin Film Magnetic Actuatorsand MOEMS Biosensor

Koc University


23

Understanding Soft Magnetic Thin-Film Actuators

•FACT: Unlike thick magnetic films, force can be attractive or repulsive.•WHY? Magnetization vector remains in-plane due to strong shape anisotropy and the whole structure rotates instead of magnetization•FACT: Unlike permanent magnets, force is NOT bidirectional•WHY? Changing current direction, rotates both H and M vectors 180degrees, thus force direction remains the same

Push region Pull region

Torque M H┴

Where M max (Hr, Msat)

Koc University


24

Modeling Soft Magnetic Thin Film as Array of Permanent Magnets

Isikman et al, JSTQE 2007

Isikman, et al, IEEE J. Magnetism (accepted) about dynamics & hysteresis modeling

Thin magnetic film in external magnetic field

Integrated planar coil

Attractive to use magnetic thin films such as Ni or NiFe as structural MEMS/NEMS layer.

Equivalent system

TNET

FNET

Mirror assumed rigid

Koc University

The magnetic layer is modeled as

an array of permanent magnets:

New Actuator Model for High-Permeability Thin Film Actuators

Isikman et al, IEEE JSTQE 2007

NNN

NNN

HtWMF

HtWMF

'

111

1

1

'1

N

iiiNET FFF

cos)1)(( ' LNFFT NNN

N

iiNET TT

2

Force Calculation:

Torque Calculation:Equivalent system

TNET

FNET

Mirror assumed rigid

Koc University

New Model Validation for Permalloy Thin Films

y=9y=-4

Model can handle:

•Non-uniform fields

•Saturated/unsaturated film

Isikman, Ergeneman, Yalcinkaya, Urey, IEEE JSTQE 2007

Koc University


27

Target Molecule

Gold

Probe Molecule

Target Binding

Chip

Chip

Chip Chip

Ch ip Chip Chip SiNX

MEMS Chemical/Bio Sensors

• Chemical to Mechanical Free Energy Transduction

• Universal Platform for Any Chemical Reaction

• Mass loading -Resonance Frequency

• Label Free

• Multiplexing

Interactions• Steric• Electrostatic• van der Waals

Before Reaction

After Reaction

Thundat et al. (ORNL), APL’94; Chen et al.,” J. Appl. Phys (1995).

Koc University


28Biosensor Research at Koc University

Blood sample

Disposable MEMS Chip Reflector

for optical readout

Functionalized cantilever array(parallel operation)

EM actuation coil / Optoelectronics module for readout

Electronics control/readout

Dynamic Mode Actuation: Use magnetic material as structural material instead of Si or SiNDetection: Optical using integrated grating interferometer

TÜBİTAK

Protein-ligand interaction changes the dynamics of Micro/nano cantilevers

Koc University


29Diffraction Grating Readout

Gap /

• Grating pattern can be on the moving or fixed structure

• Extremely sensitive: can detect mechanical deflections on the order of 2x10-4A/Hz½ at 20KHz. Used for AFM and acoustic sensing; IR sensing;

Ferhanoglu, Toy, and Urey, PTL 2007

Degertekin, et.al. JSTQE 2004 (Georgia Tech)

0th1st

3rd

-1st

-3rd

gapGrating

Si substrate

PD0PD1

Electro-coil

NiFe cantilever

Koc University


30Simple Microfabrication

• Magnetic actuation of Nickel thin film (~1um thick)

Silicon

Au + Ni

PR

Si (doped)

Photoresist

Mask

Ni or NiFe

Remove PR

Isotropic Silicon Etching

~100um5-10um

In collaboration with Profs. E. Alaca and H. Kavakli at Koc University

Koc University


31

Fabricated Cantilevers with Diffraction Gratings(Fabricated in our clean room)

They all work despite not so great surface quality Thanks to AC-coupled detection, and bias/noise rejection

of diffraction grating readout,

Ozturk et al, PTL 2008

Koc University


32Bio-detection Results

Resonance frequency shift of a cantilever due the attachment of human kappa opioid receptors (hKOR) to the Au surface.

180Hz shift 85pg of mass

Ozturk et al, PTL 2008

SENSITIVITY is GOOD, future work will focus on improving SPECIFICITY

Koc University

Comb Actuated Devices:

1. Fourier Transform Spectrometer2. MEMS Stages with Microlens

arrays

Koc University


34Portable Mid/Far IR Spectroscopy

• FTIR spectroscopy is the common choice due to single detector operation

• Requirements for compact FTIR Spectrometers– Translating mirrors with long travel

range– Precision scanning – Real-time operation– Large clear aperture

• Approaches– Michelson interferometer– Lamellar grating interferometer

(eliminates beam splitter and reference mirror, more compact)

Manzardo, Opt. Let., 29, 1437–1439, 2004.

Schenk, Optical MEMS 2005Kenda, Proc. of SPIE, 6186, 618609, 2006.

Ataman, JMM, 16, 2517-2523, 2006

Koc Univ., TR

U. Neuchatel, CH

Faunhofer IPMS, DE

Koc University


35FTS : Lamellar Grating Interferometer Based

4d N

a

/a

/a

2 4

coscenter

dI A

0

0.2

0.4

0.6

0.8

1

0 0.5 1 1.5 2

Faz Derinliği (d /)

Işık

şid

deti

Grating Depth (d/)

Inte

nsit

y

0

0.2

0.4

0.6

0.8

1

0 0.5 1 1.5 2

Faz Derinliği (d /)

Işık

şid

deti

Grating Depth (d/)

Inte

nsit

y

Monochromatic Light

Grating Side View

FourierTransform

0 /

DC

Spectrum

Koc University


36MEMS Grating: Features

x

yz 1

1

2

2

3

4

4

4

4

1

2

3

4

Fixed Fingers

Movable Fingers

Rigid Backbone

Folded Flexures

Size 2.7mmx2.65mmFlexure Length 1.2mmFlexure Width 10-5m# of Folds 4Backbone Width 250mFinger Width 70mFinger Gap 5mFinger Length 1.2mmDiffraction angle 7mrad (@635nm)

Dimensions of the Device

o Comb fingers function as grating, actuators and position feedback

o Large clear aperture and good optical efficiencyo Simple fabrication process

Technology Licensed to Fraunhofer IPMS

Koc University


37

400 500 600 700 800 900 10000

0.2

0.4

0.6

0.8

1

Wavelength (nm)

No

rm

alized

In

ten

sity

FTS MeasuementReference Measurement

Spectral Measurements

FTS Measurement: =638.8nm, FWHM= 24 nm

Commercial visible spectrometer =638.8nm; FWHM =1.5 nm

FTS Theory: = 2.3nmfor 30um deflection

Measured Narrowband Spectrum

Ataman, Urey, Wolter, J. Micromechanics and Microengineering, Vol. 16, p. 2517, 2006

Photodetector Signal Measured Broadband Spectrum

Koc University


38Currrent and Future Work in this area

• MEMFIS Project “Ultrasmall MEMS FT-IR Spectrometer“ started in 2008 (funded by EC-FP7)

• Develop a MEMS based compact FTS for mid and long IR applications

www.memfis-project.eu

Koc University

Scanned Imaging using MEMS Stages and Microlens Arrays

(Microfabrication 2nd run planned at EPFL clean rooms)

Koc University


40Scanning with MLAs

A. Akatay, C. Ataman, H.Urey, Optics Letters, 31 (19), 2861-2863, 2006.

laser

PSLMLA1 DMLA

FL

• Beam steering is possible by laterally moving a collimating lens wrt focusing lens • Using microlens arrays (MLA) allows for large angle steering with small lateral displacements • However, beam steering with MLA has a fundamental diffraction related problem!

•Can address only discrete angles set by period of MLA

• Our group showed that moving PSL and MLA1 in SYNC allows for continuous addressing!

Moving MLA only

Moving PSL and MLA together

Koc University


41

Demonstrated Continuous Scanning with Microlens Arrays

(a)

(b)

a.u.

/ d(c)

-4 -3 -2 -1 0 1 2 3 40

50

100

150

200

(=0.532m) and the beam size is around 600m pitch (d) = 200m

Can fit ~150 spots with continuous addressing

>1000 resolvable spots using Higher f# lenses and 2mm clear aperture

~40 discrete addressable spotsUsing 650um clear aperture

*Akatay, Ataman, Urey, Optics Letters, 2006

*Akatay, Urey, Optics Express, 2007

Koc University


42MOS: Fabricated Devices

• Fabricated at Chalmers University

• 20 m and 50 m thick (SOI)• Fabrication process similar to

1st gen. MEMS spectrometer

Microscope Pictures

SEM Pictures

Koc University


43Fabricated MLAs

• Replicated on 20 m thick Cytop layer

• 100% Fill Factor• 75m pitch size• f/4 (300m f. length)• Embossed using KS SB6

Wafer Bonder

• New fab run planned at EPFL (Feb-April 2009)

Hedsten et. al., MME 2008(Koc and Chalmers collaboration)

Koc University


44Summary Remarks

• MOEMS (i.e., moving micromechanical structures combined with laser light sources and micro-optics) is a powerful technology and enables a number of applications:

– Thermal sensors, 2D and 3D Displays, Bio-sensors, Spectroscopy, and Imaging are some of the applications explored at Koc U.

• 3-types of EM actuators are discussed: moving coil, moving-magnet, and soft-magnetic film. Selection depends on application.

• Best reported MEMS Scanner performance is achieved using bi-magnetic Lorentz force actuator. Suitable for pico-projector applications.

• FR4 mechanical properties and integration with optics not explored before:

– offers low-cost and high degree of integration

– good choice for many applications: 3D displays, FTS, advanced imaging with dynamic focusing, etc.

• Comb-actuated in-plane and out-of-plane moving platforms are utilized for high-performance FTS and beam steering applications

– Comb actuation provide compact form-factor and low-power.

• Mechanical coupling provides an interesting way to actuate, can be used both for EM and ES actuated MEMS devices.

Koc University


45Acknowledgments

All the past and current students and researchers at OML

Funding Resources:• Microvision Inc. (USA)• FP6 Projects: NEMO, 3DTV, MC2ACCESS,

MINOS-Euronet• FP7 STREP Projects: MEMFIS, HELIUM3D• ASELSAN Inc. (Turkey)• Fraunhofer-IPMS (Germany)• TÜBİTAK (Scientific and Technical Research

Council of Turkey)• TÜBA-Distinguished Young Scientist Award,

Turkey• NSF (USA)

MEMS / Micro-Optics / 3D Displays• Post-doctoral research positions

available• PhD positions available

koc university moems for display, spectroscopy and imaging applications hakan urey koç university...

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