Koc University MOEMS for Display, Spectroscopy and Imaging Applications Hakan Urey Koç University – Istanbul, TURKEY EPFL 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 Hakan Urey, Koc University-Istanbul 3 Prof. Hakan Ürey (Director) Dr. V.C. Kishore (Post-doc) Sven Holmström (Researcher) Selim Ölçer (Technician) Graduate Students Onur Ferhanoglu Aslıhan Arslan Huseyin R. Seren Erdem Erden Gökhan Hatipoğlu S. Kutal Gökçe Duygu Kutluoğlu (KU-EPFL) Ersin Huseyinoglu Undergraduate Assistants Utku Baran Erman Timurdoğan Özge Tekin Baran Gözcü Özerk Memiş F. Firat Gonen Research Focus: Micro-optics, MEMS/NEMS sensors and actuators, 2D/3D Display and Imaging Systems

Koc University Hakan Urey, Koc University-Istanbul 4 Outline: 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 Hakan Urey, Koc University-Istanbul 5 OML Research Projects: MOEMS Thermal Imaging Sensor Array Bimaterial Legs 1st order -1st order 0th order IR Diffraction Grating readout laser IR Intensity Gap / wavelength Licensed to ASELSAN, TR JAP 2006; PTL 2008; Sens&Act 2009 Advantages - Eliminates the need for electrical connection - Interferometric sensitivity  Recent collaboration with EPFL (Prof. Leblebici)

Koc University Hakan Urey, Koc University-Istanbul 6 Two-wavelength Interferometry for Extended Range Imaging with Grating Interferometry λ1λ1 λ2λ2 λ 1 & λ 2 PD2 PD1 g O. Ferhanoglu, F. Toy, H. Urey, PTL 2007 Unambigious detection Full range

Koc University Hakan Urey, Koc University-Istanbul 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-STREP HELIUM3D 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 Hakan Urey, Koc University-Istanbul 9 Needs a MEMS Scanner Case for a scanning mirror & laser light –Together they address all the critical properties Small size Low power Bright Single Mirror scanner Image plane Light source

Koc University Hakan Urey, Koc University-Istanbul 10 Microvision 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 Hakan Urey, Koc University-Istanbul 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 Hakan Urey, Koc University-Istanbul 12 Microfabrication 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 (2005); Urey et al, Optical MEMS 2006; Yalcinkaya et al, JMEMS (2006)

Koc University Hakan Urey, Koc University-Istanbul 13 Summary: MEMS Scanner Performance Comparison 2D Bimagnetic MEMS Scanner Yalcinkaya, Urey, Montague, Brown, Sprague, JMEMS (2006) Horizontal Resolution Vertical Resolution

Koc University Hakan Urey, Koc University-Istanbul 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 Hakan Urey, Koc University-Istanbul 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 Hakan Urey, Koc University-Istanbul 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 Hakan Urey, Koc University-Istanbul 18 Moving Coil with Lorentz Force Actuation I FR4 scanner and coil Urey et al, PTL mm x 5mm Electrical vias FR4 substrate Double-sided Cu coils Mirror attached on one side Typically < 200Hz operation

Koc University Hakan Urey, Koc University-Istanbul 19 FR4 Applications: Imaging with Dynamic Focusing  Moving LD mounted on FR4 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 Hakan Urey, Koc University-Istanbul 20 FR4 Laser Scanner with Dynamic Focusing Experimental Results -  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 Hakan Urey, Koc University-Istanbul 21 FR4 and Silicon Technology Comparison for EM Actuators FR4Silicon Fabrication TechnologyStandard PCBMEMS Density [kg/m^3] Density of copper8960 Young's Modulus [Gpa] Torsional Modulus [Gpa]2-551 Min Coil Trace Width / Spacing 100um 10um Min Via Hole Size 350um (25um with laser) Min feature size 100um (drill); 20um laser (5um in 2009) 2um (lithography) Copper thickness30um10um Number of Coil layers Resistance / PowerLowHigh difficult

Koc University Type 3: Thin Film Magnetic Actuators and MOEMS Biosensor

Koc University Hakan Urey, Koc University-Istanbul 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 (H r, M sat )

Koc University Hakan Urey, Koc University-Istanbul 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 T NET F NET 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 Force Calculation: Torque Calculation: Equivalent system T NET F NET 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 Hakan Urey, Koc University-Istanbul 27 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 Hakan Urey, Koc University-Istanbul 28 Biosensor 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 SiN Detection: Optical using integrated grating interferometer TÜBİTAK Protein-ligand interaction changes the dynamics of Micro/nano cantilevers

Koc University Hakan Urey, Koc University-Istanbul 29 Diffraction Grating Readout Gap / Grating pattern can be on the moving or fixed structure Extremely sensitive: can detect mechanical deflections on the order of 2x10 -4 A/Hz ½ at 20KHz. Used for AFM and acoustic sensing ; IR sensing; Ferhanoglu, Toy, and Urey, PTL 2007 Degertekin, et.al. JSTQE 2004 (Georgia Tech) 0 th 1 st 3 rd -1 st -3 rd gap Grating Si substrate PD 0 PD 1 Electro-coil NiFe cantilever

Koc University Hakan Urey, Koc University-Istanbul 30 Simple 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 ~100um 5-10um In collaboration with Profs. E. Alaca and H. Kavakli at Koc University

Koc University Hakan Urey, Koc University-Istanbul 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 Hakan Urey, Koc University-Istanbul 32 Bio-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 Spectrometer 2. MEMS Stages with Microlens arrays

Koc University Hakan Urey, Koc University-Istanbul 34 Portable 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, Schenk, Optical MEMS 2005 Kenda, Proc. of SPIE, 6186, , Ataman, JMM, 16, , 2006 Koc Univ., TR U. Neuchatel, CH Faunhofer IPMS, DE

Koc University Hakan Urey, Koc University-Istanbul 35 FTS : Lamellar Grating Interferometer Based a /a  /a  Monochromatic Light Grating Side View Fourier Transform 0  /  DC Spectrum

Koc University Hakan Urey, Koc University-Istanbul 36 MEMS Grating: Features Fixed Fingers Movable Fingers Rigid Backbone Folded Flexures Size2.7mmx2.65mm Flexure Length1.2mm Flexure Width 10-5  m # of Folds4 Backbone Width 250  m Finger Width 70  m Finger Gap 5m5m Finger Length1.2mm Diffraction angle7mrad Dimensions of the Device oComb fingers function as grating, actuators and position feedback oLarge clear aperture and good optical efficiency oSimple fabrication process Technology Licensed to Fraunhofer IPMS

Koc University Hakan Urey, Koc University-Istanbul 37 Spectral Measurements FTS Measurement: =638.8nm,  FWHM = 24 nm Commercial visible spectrometer =638.8nm;  FWHM =1.5 nm FTS Theory:  = 2.3nm for 30um deflection Measured Narrowband Spectrum Ataman, Urey, Wolter, J. Micromechanics and Microengineering, Vol. 16, p. 2517, 2006 Photodetector SignalMeasured Broadband Spectrum

Koc University Hakan Urey, Koc University-Istanbul 38 Currrent 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

Koc University Scanned Imaging using MEMS Stages and Microlens Arrays (Microfabrication 2 nd run planned at EPFL clean rooms)

Koc University Hakan Urey, Koc University-Istanbul 40 Scanning with MLAs A. Akatay, C. Ataman, H.Urey, Optics Letters, 31 (19), , laser PSL MLA1 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 Hakan Urey, Koc University-Istanbul 41 Demonstrated Continuous Scanning with Microlens Arrays ( =0.532  m) and the beam size is around 600  m pitch (d) = 200  m Can fit ~150 spots with continuous addressing >1000 resolvable spots using Higher f # lenses and 2mm clear aperture ~40 discrete addressable spots Using 650um clear aperture *Akatay, Ataman, Urey, Optics Letters, 2006 *Akatay, Urey, Optics Express, 2007

Koc University Hakan Urey, Koc University-Istanbul 42 MOS: Fabricated Devices Fabricated at Chalmers University 20  m and 50  m thick (SOI) Fabrication process similar to 1 st gen. MEMS spectrometer Microscope Pictures SEM Pictures

Koc University Hakan Urey, Koc University-Istanbul 43 Fabricated MLAs Replicated on 20  m thick Cytop layer 100% Fill Factor 75  m pitch size f/4 (300  m 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 Hakan Urey, Koc University-Istanbul 44 Summary 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 Hakan Urey, Koc University-Istanbul 45 Acknowledgments 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