mems for medical applications

MEMS for Medical Applications Alissa M. Fitzgerald, Ph.D. | 20 March 2013

GSA Meeting, March 2013 © AMFitzgerald 2013

Outline

• About AMFitzgerald • Why MEMS are exciting for medical applications • Research applications • Diagnostic applications • Medical devices • Packaging challenges


Mission: Your Partner in MEMS Product Development


A complete solution from concept to production

• Project management • Multi-disciplinary engineering team • In-house prototype fabrication (150 mm wafers) by our

engineers, not operators • Smooth transition to production partners • Leverage our supplier ecosystem

Technology Strategy

Foundry Production

AMFitzgerald in-house Strategic partners

Design Simulation

Prototyping Low Volume Production

Package & Test


Why MEMS are exciting for medical applications

• Cell-compatible size scales • 2-100 micron-sized features are easy to make



• Many materials used in MEMS are biocompatible: – Silicon (under study) – Silicon dioxide (glass, fused silica, quartz) – Precious metals: Gold, titanium – Polymers: Polydimethylsiloxane (PDMS), Parylene, etc. – Bio-degradeable materials


• Ease of electronics integration enables sophisticated capabilities in small form factor: – Signal processing and analysis – Wireless capability

Battery-less operation (power/read)

Telemetry for medical sensor network (with cell phone)


Integrated Pressure Sensor

Source: IMD

MEMS sensor

Stacked MEMS and

ASIC chips, wirebonded

Source: Chipworks/Kionix

Research Applications


Microfluidics

• Laboratory tools: genomics, proteomics, drug discovery

• Microfluidics enable: – Reduction of fluid sample size – Arrayed test sites – up to thousands of tests

per chip

Caliper LifeSciences Affymetrix


Cell Manipulation

• Flow cytometers and cell sorters • Patch clamps for cell electrophysiology • Cell scaffolds for artificial organs and tissue

engineering – Liver, kidney – Working on biodegradable scaffolds

Dr. Joseph Vacanti, Harvard Medical School

Jeffrey Borenstein, Draper Laboratory

Diagnostic Applications


MEMS Pressure Sensors

• Used in non-invasive medical equipment since 1980’s – Respiratory equipment – Blood pressure cuffs

• Invasive uses increasing – Catheter tip sensors

• Many manufacturers: – GE Sensors – Measurement Specialties – Silicon Microstructures – ISSYS

Source: GE

Source: ISSYS


i-STAT/Abbott sensor arrays

• Sample interacts with membranes and films containing reagents.

• Biosensor chip measures reaction output via: – Ion-selective electrode

potentiometry: Na, K, Cl, Ca, pH

– Current measurements: Glucose, oxygen

– Conductivity: Hematocrit

Source: i-STAT/Abbott


Microneedles

• Pain-free blood sampling and drug delivery

Source: Silex Microsystems

Source: Debiotech SA

Medical Devices

St. Jude Medical: CardioMEMS Pressure Sensor

• FDA-approved – Aorta stent graft

monitoring – Pulmonary artery

pressure measurement – Mean pressure, systolic

pressure, diastolic pressure, heart rate and cardiac output

• Capacitive pressure sensor with wireless readout, catheter deployed

• Readout at doctor’s office

© AMFitzgerald 2013

Source: CardioMEMS

Fused silica (glass) capacitive pressure sensor

Nitinol wire basket

Inductor coil

30 x 5 x 1.5 mm

Proteus Biomedical: Patient pill compliance system

• Edible chips • Powered patch

transmits data via Bluetooth to mobile device

• FDA approved www.proteusdigitalhealth.com


Receiver patch contains: battery, temp sensor, MEMS accelerometer, Bluetooth transmitter

1 x 1 mm silicon chip with Mg and Cu electrodes

Second Sight: Argus II Retinal Prosthesis

• FDA approved • Electrical stimulation

of retina for macular degeneration

• MEMS microneedle electrodes

• www.2-sight.com


Source: Second Sight

Source: NYTimes

Sensimed Triggerfish IOP monitor

• Continuous intraocular pressure (IOP) measurement for glaucoma diagnosis

• Disposable lens • Strain gage with wireless telemetry • Under evaluation in Europe

• www.sensimed.ch


Recorder syncs with doctor’s computer via Bluetooth


Debiotech: Insulin Micropumps

• Volumetric pump for insulin delivery

• www.debiotech.com

Source: Debiotech SA


Challenges in MEMS for Medical Applications

• Packaging, packaging, packaging – MEMS chip often needs ASIC – Electrical interconnect – Mechanical stress management – Small form factor – Hermeticity (for both MEMS function and biocompatibility)

• Sterilization – Gamma, e-beam (damaging to electronics and some plastics) – Ethylene oxide (can be absorbed by plastics) – Steam 121-134C (creates problems with material CTE

mismatch, glass transition temperature)


Summary

• MEMS is a growing suite of manufacturing tools and techniques – Newest frontier: flexible (and biodegradable) materials

• Huge opportunity in medical and biotech applications – Compatible materials and sizes – Electronics integration

• Challenges remain in packaging – Hermeticity – Sterilization


Contact

• Alissa Fitzgerald: [email protected] • 650 347 MEMS x101

mems for medical applications

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