Why silicon MEMS? Silicon is a strong material... Photolithography. Micromachining. Dicing and packaging

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1 Why silicon MEMS? Small Identical Large volumes (low cost per unit) School of Electrical Engineering Royal Institute of Technology Silicon is a strong material... Photolithography 10 µm thick silicon wafer (Virginia Semiconductor Inc.) SEM-picture of the deflection of a silicon cantilever beam (Material Science, Uppsala University). Photoresist spin-on process From Madou Talks Dicing and packaging Micromachining Dicing of silicon wafer Electronics chip package Pressure sensor chip package (a) (b) (c) MEMS at DARPA 1

2 Micromachining Our Main Research Areas MEMS at DARPA MED-MEMS BIO-MEMS OPTO-MEMS RF-MEMS Ultraminiaturized Blood Pressure Sensor Aorta Coronary artery Diaphragm Piezoresistor P a P d MED-MEMS Stenosis Guide-wire Pressure sensor location Diced chip 100 µm Cavity Pressure sensor chips and a 1mm cannula needle Commercialised by RADI Medical Systems, Uppsala Modern surgery A Lift Force Gas Flow Sensor Principle Application Ventilator F lift Flow sensor Flow Sensors Flow Flow Realization α 6.8 mm 3 mm Detector beam with polysilicon strain-gauge Source: Annual Report Instrumentarium 2

3 Modern surgery An integrated IR gas analysis system Ventilator CO 2 sensor Application Reference sources Sample sources CO 2 Sensor IR-source chip Al bonding pads CO 2 -filter chip CO 2 1 mm Silicon wafers CO 2 chamber Gas flow 10 mm Gas flow IR bandpass filter IR-detector Glass wafer Source: Annual Report Instrumentarium Modern surgery Origin of Biopotentials Micromachined EEG Electrode Biopotential Electrodes Source: Source: Annual Report Instrumentarium Source: The Outer Skin - An Electrical Insulator Micromachined EEG Electrode Array of Microspikes Micromachined EEG Electrode Stratum Corneum Ion Current No Sensory Organs Spiked Electrode No Gel! 3

4 Microspike Array Barbed Spikes for Chip Skin Attachment 0.03 mm 0.16 mm Attachment Performance Micromachined EEG Electrode EEG Recording Micromachined EEG Electrode 15 Zipprep Electrode Spiked Electrode 10 5 EEG [µv] Measured with Datex-Ohmeda S/5 Monitor Time [s] Similar Signals Modern surgery The Outer Skin - A Biochemical Barrier Transdermal Liquid Delivery Drug Stratum Corneum Transdermal Drug Delivery No Sensory Organs Dendritic Cells Source: Annual Report Instrumentarium 4

5 Standard Hypodermic Needles Transdermal Liquid Delivery Transdermal Drug Delivery System Microneedles Painful Intradermal delivery difficult Hollow Microneedle Design Issues Microneedles Side-Opened Microneedles Delivery Area Skin Penetration Bore Diameter Clogging Freedom of Design Hypodermic- and Microneedles 5

6 Nano-Sharp Hollow Microneedles Transdermal Drug Delivery System SEM-pictures of the microneedle. The sharp tip is a result of a final oxidation and a consecutive oxide strip. The needle tip radius is below 100 nm. Expandable Microspheres Dosing and Actuation Unit Test Result Principle Application 1 bar Lab-on-a-Chip BIO-MEMS 6

7 Biosensor System for Drugs and Explosives A MEMS Air-to-Liquid Particle Collector Thermally responsive PDMS composite Expandable beads mixed with PDMS (XB-PDMS) The interface was incorporated in an electronic nose system and successfully detected heroin and cocaine samples Large thermal expansion (> 100%) High flexibility inherited from the silicone elastomer PDMS Non-toxic and chemically inert Highly integrable actuator Allows for various fabrication methods e.g. soft lithography, casting, spinning In collaboration with Biosensor Applications Sweden AB ( XB-PDMS Actuator Prototype Expandable Beads XB-PDMS Actuator Operation Expandable Beads Microfluidic demonstrator showing the multilayer structure No heat => Open valve Heat => Closed valve B. Samel, V. Nock, A. Russom, P. Griss, G. Stemme, Transducers 2005 B. Samel, J. Melin, P. Griss, G. Stemme IEEE MEMS 2005 Microfluidic Network XB-PDMS Valves & Pumps XB-PDMS Lab-on-a-Chip Movies XB-PDMS Valves & Pumps B. Samel, P. Griss, G. Stemme, Transducers 2005 B. Samel, P. Griss, G. Stemme, Transducers

8 Transdermal Drug Delivery Patch Transdermal patch Figure 2. Schematic view of the micromachined drug delivery device in development by KTH. OPTO-MEMS Figure 2. Schematic view of the micromachined drug delivery device in development by KTH. Micro Mirror Optical Router Digital Mirror Device Board contains a 2000 x 1000 array of 16 x 16 µm micromirror devices The micro-mirrors route information in the form of photons to and from any of 256 input/output optical fibers. Lucent Technologies Inc. Source: Light-Wave Magazine, Vol.17, No. 1, 2000 Texas Instruments Inc. MEMS and IC Compatibility Torsional Monocrystalline Silicon Micromirrors The Task The integration of high-performance MEMS materials with Integrated Circuitry Concept Hinge Realization The Problem Limited thermal budget, i.e. post IC processes must be below 450 C A Solution Wafer-level film transfer using adhesive bonding Mirror Membrane Distant Holder F. Niklaus, S. Haasl and G. Stemme, S3-MST, KTH Post Addressing Electrode Application Areas: Pattern Generators in Maskless Lithography Systems Optical Switch and Cross Connector Arrays 8

9 Wafer-Level Integrated IR Detector Arrays with CMOS Legs Membrane (Thermistor) Vias RF-MEMS Bolometer arrays with 320x 240 pixels, 0.7 µm thick membranes, 40x40 µm2 pitch size and 3x3 µm2 small vias. Allows the combination of high performance bolometer materials with CMOS read out electronic. MEMS Switch ( Conventional ) Novel MEMS Switch Concept Majumder, 1997 Realization of Novel MEMS Switch Concept MEMS Switch Projects Telecommunication MEMS Switch Projects: Automotive Radar (Vinnova) Automated Cross-Connects (Network Automation) 9

10 MEMS Switch Arrays top part top electrode pads membrane electrode pads MEMS = M M$? signal IN pads bottom part signal OUT pads 3 mm assembled switch 5x5(x2) unit, 2x2(x2) switch array assembled 20x20(x2) switch array 10