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When Engineering Generates Life: An Overview of Medical Devices and Packaging Requirements

Guna Selvaduray College of Engineering San Jose State University IMAPS Northern California Chapter November 1, 2006

[email protected]

Presentation Outline

Economic Background & Driving Forces What is a "Biomedical Device" Biomedical Device Industry & Driving Forces Biocompatibility Types of Biomedical Devices Design & Manufacture of Biomedical Devices Biomedical Devices Concentration at SJSU

G. Selvaduray ­ SJSU ­ November 1, 2006

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Bio ...... What?

Bio-technology Bio-pharmaceuticals Bio-informatics Bio-medical engineering Bio-Medical Devices Bio-electronics Bio-sensors Bio-nano, or is it Nano-bio? Bio.., Bio..., Bio....

G. Selvaduray ­ SJSU ­ November 1, 2006

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Some Statistics

In California:

Number of companies: 2,700 Revenues: $62 billion Employment: 258,000 57% small businesses

42% work in making medical devices, instruments and diagnostic tools 11% - between 50 ~ 100 employees 46% - less than 50 employees

Source: California Healthcare Institute 2006 Report

G. Selvaduray ­ SJSU ­ November 1, 2006

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Silicone Valley ???

Biomedical Devices is a "growth area" according to Joint Venture Silicon Valley Significant presence of biomedical device companies in Silicon Valley 86,000 biotech jobs in Bay Area 31,000 in biomedical devices (36%) Bay Area home to largest concentration of medical device start-ups in the USA Engineering oriented field within biotechnology area

G. Selvaduray ­ SJSU ­ November 1, 2006

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What is a "device"?

"An instrument, apparatus, implement, machine, contrivance, implant, in vitro reagent, or other similar or related article, including a component part, or accessory which is:

intended for use in the diagnosis of disease or other conditions, or in the cure, mitigation, treatment, or prevention of disease, in man or other animals, or intended to affect the structure or any function of the body of man or other animals, and which does not achieve any of it's primary intended purposes through chemical action within or on the body of man or other animals and which is not dependent upon being metabolized for the achievement of any of its primary intended purposes."

US Food & Drug Administration G. Selvaduray ­ SJSU ­ November 1, 2006

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In other words ...

A broad range of surgical devices and equipment used in cardiovascular, orthopedics, respiratory, ophthalmic, neurology, urinary, disposable, infection and more. Drugs and medications are not included

G. Selvaduray ­ SJSU ­ November 1, 2006

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Driving Forces

Societal

Aging and more affluent population Greater demand for, and awareness of, better quality of life Preventive therapies Health care cost containment

Technological

Improved technological capabilities Optics & fiber optics Miniaturization of electronics Micro-fabrication Imaging technologies IT Improvements Nano, nano, nano Many others

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G. Selvaduray ­ SJSU ­ November 1, 2006

Biocompatibility

The ability of a material to perform with an appropriate host response in a specific application Examples of "appropriate host response":

Resistance to blood clotting Resistance to bacterial colonization "Uncomplicated" healing

G. Selvaduray ­ SJSU ­ November 1, 2006

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Biocompatibility - 2

Biocompatibility depends on the purpose of the implant Teflon vascular prosthesis:

Inside must have blood-compatible surface, i.e., should not cause adhesion or clotting Outside must firmly attach to surrounding fibrous tissue but must not cause fibrous hyperplexia

Source:http://www.sjm.com/devices/devicegrid.aspx?location=us G. Selvaduray ­ SJSU ­ November 1, 2006

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Biocompatibility - 3

Bioactive material: one that elicits a specific biological response at the interface of the material, resulting in the formation of a bond between the tissues and the material. Bioinert material: one that elicits minimal biological response Bioresorbable material: One that is (gradually) replaced by normal tissues, thereby excluding possible long term effects.

Source: Hench & Wilson G. Selvaduray ­ SJSU ­ November 1, 2006

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Biocompatibility - 4

Tests need to be application and tissue-specific Dominated by surface characteristics, e.g., roughness, porosity, charge, chemistry, surface tension (of the solid), texture, subsurface grain structure, wettability, etc.

G. Selvaduray ­ SJSU ­ November 1, 2006

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Stenting

Balloon catheter Balloon expansion

316L stainless steel stent

NiTi self-expanding stent

Before stenting showing blocked artery

G. Selvaduray ­ SJSU ­ November 1, 2006

After stenting

Credit: Steve Trigwell

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Coronary Stent

Stent: any material used to hold tissue in place Usually refers to thin metallic mesh tubes inserted into arteries to permanently open narrowed sections Domestic market ~$2.6 B annually (www.forbes.com) http://www.ne.jp/asahi/ueda/stroke/stent.html Current materials

316L Stainless SS Co-Cr alloy (FDA approved this year) Nitinol (Gaining popularity)

Equiatomic Ni-Ti Shape memory alloy Super-elastic

G. Selvaduray ­ SJSU ­ November 1, 2006

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STENT SERVICE REQUIREMENTS

Biocompatible Corrosion Resistant to internal human bioenvironment Pliability for bending Cyclic loading Sterilizable

Must be delivered through artery ~1 to 2 Hz with heart beat Must endure some type of sterilization

http://www.uthscsa.edu/mission/spring98/stent.html

G. Selvaduray ­ SJSU ­ November 1, 2006

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Issues

Biocompatibility

Nickel release into body (many patients allergic to Ni)

Dissolution from corrosion processes

Corrosion byproducts that can get in bloodstream (embolism) Pliability to prevent tearing tissue

Performance

Fatigue (~3.7M cycles/year) Corrosion resistance Oxide layer repassivation capability

Fatigue Stress Corrosion Cracking Corrosion Fatigue

Credit: Robert McReynolds

G. Selvaduray ­ SJSU ­ November 1, 2006

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Other Design Issues

Radiopacity Flexibility Uniform expansion Avoid shortening during expansion Restenosis/ thrombogenecity Elastic recoil Minimize metal-tissue contact area

Wall coverage Surface area

Avoid collapse of expanded stent Avoid sharp edges Packaging Sterilization

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G. Selvaduray ­ SJSU ­ November 1, 2006

Drug Eluting Stents

Design/Materials Issues

Coating materials Coating strategy Elution rate

G. Selvaduray ­ SJSU ­ November 1, 2006

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Vena Cava Filters

G. Selvaduray ­ SJSU ­ November 1, 2006

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Hip Implant

Metal acetabular shell UHMWPE Liner Femoral Head

Femoral Stem

http://www.materials.qmul.ac.uk/casestud/implants/index.php G. Selvaduray ­ SJSU ­ November 1, 2006

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Design & Manufacturing Issues

Materials selection Forging Adhesion Coatings Tribology

Friction Debris generation

Reliability

> 10 years useful life

Biocompatibility Stress shielding and tissue atrophy Packaging Sterilization

Stress analysis and modeling

G. Selvaduray ­ SJSU ­ November 1, 2006

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Defibrillator

Electrical contacts

Outer body (Ti)

Device for arresting the uncontrolled twitching or quivering of the auricular or ventricular heart muscles

G. Selvaduray ­ SJSU ­ November 1, 2006

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Defibrillator Implant

Pulse Generator

Electrode (Pt-Ir) with polyurethane or silicone insulation

Source: Biomedical Engineering Handbook, CRC Press, p 1287

G. Selvaduray ­ SJSU ­ November 1, 2006

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Defibrillator: electronic components

32-lead Gull Wing device Surface mounted on Ceramic substrate Battery

Metallization Capacitors, surface mounted

G. Selvaduray ­ SJSU ­ November 1, 2006

Surface mounted devices

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Defibrillators: more components

Capacitor Bank Surface mounted transformer Flex circuit

Terminals encased in plastic housing

G. Selvaduray ­ SJSU ­ November 1, 2006

Ceramic substrates, 3 ­ brazed or soldered Soldered leads

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VeriChip

Microchips that can be implanted under a person's skin and used to confirm health history and identity Miniaturized (12 mm x 1.2 mm), implantable radio frequency identification device

G. Selvaduray ­ SJSU ­ November 1, 2006

Sources: http://www.verichipcorp.com/content/company/our_technology and http://www.techweb.com/wire/story/TWB20030718S0003 26

Characteristics of Verichip

RFID Low power Low heat dissipation Form factor ­ small Health-monitoring system Emergency medical information

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G. Selvaduray ­ SJSU ­ November 1, 2006

Cochlear Implant

RF Communications Signal Processing

G. Selvaduray ­ SJSU ­ November 1, 2006

Source: http://www.nidcd.nih.gov/health/ 28 hearing/images/ear_cochlear.asp

Responsive Neurostimulator

For treatment of medically refractory partial epilepsy Implantable and external products, accessories and tools. Implantable components include

Responsive neurostimulator (RNS)

A programmable, battery powered, microprocessor-controlled device that delivers a short train of electrical pulses to the brain through implanted leads designed to detect abnormal electrical activity in the brain and respond by delivering electrical stimulation to normalize brain activity before the patient experiences seizure symptoms implanted in the cranium and connected to one or two leads that are implanted near the patient's seizure focus.

Depth leads and cortical strip leads

Source: Neuropace website G. Selvaduray ­ SJSU ­ November 1, 2006

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Design/Manufacturing Issues

Packaging Biocompatibility Regulations Food & Drug Administration Reliability EMI Issues System traceability ­ 100% Size, weight, volume Power output Moisture resistance Mechanical shock Vibration Thermal shock Battery life Corrosion Sterilizability Sterility Supplier development and reliability Labeling Liability (?)

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G. Selvaduray ­ SJSU ­ November 1, 2006

Packaging

Confusion with terminology For the biomedical professionals, "packaging" does not mean "encapsulation and interconnection" It means containers for devices and labeling

G. Selvaduray ­ SJSU ­ November 1, 2006

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Packaging Issues

Wide variety of materials are used, including: Polymers ­ polyurethanes, epoxies, silicones Metals ­ titanium, AISI 316L Ceramics Polymers, especially epoxies, have been used for several years Primary issue: moisture ingression with subsequent failure of electronic circuitry Metallic packages used for hermeticity; usually welded shut Issue: lack of rf transparency Ceramic packages used when hermeticity and rf transparency are required Control of an implanted device, by an external processor, generally relies on rf Testing temperature: 37oC Service life in excess of 10 years

G. Selvaduray ­ SJSU ­ November 1, 2006

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Biocompatibility

Packaging materials, if they come into contact with human tissue, must be biocompatible Variety of biocompatibility test procedures, depending on location and function ISO standards

G. Selvaduray ­ SJSU ­ November 1, 2006

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Food & Drug Administration

Approves all products, devices, materials and drugs Approval process can take months to years, depending on product type and intended use Pre-approval testing process can be long Only complete devices are approved

While specific materials are not individually approved, their performance is important for device approval

Design process needs to keep regulatory approval in mind at all times Clinical trials are part of the development process

G. Selvaduray ­ SJSU ­ November 1, 2006

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Challenges

Time-to-Market affected by:

Design & development cycle Clinical trials Regulatory approval

Adjusting to "low-volume" competitive manufacturing practices Manufacturing needs to be close to the customer

G. Selvaduray ­ SJSU ­ November 1, 2006

Could be "high-margin" Outsourcing needs to be done judiciously

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Biomedical Devices Graduate Curriculum at the College of Engineering San Jose State University

G. Selvaduray ­ SJSU ­ November 1, 2006

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Program Vision

Establish a nationally recognized biomedical devices program that: Provides engineers with:

Interdisciplinary Practical Hands-on Graduate level

Makes SJSU's College of Engineering the partner of choice for:

Industry Government agencies

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Education in biomedical devices

G. Selvaduray ­ SJSU ­ November 1, 2006

Curriculum Overview

MSE Core Biomedical Device Concentration Area Core Electives Thesis/Project Engineering breadth Concentration area breadth Concentration area depth

G. Selvaduray ­ SJSU ­ November 1, 2006

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Biomedical Devices Core

Biol 177: Physiology for Engineers ME 267: Engineering Biomechanics MatE 175: Biomaterials Engr 272: Biomedical Devices ­ Principles & Design Engr 274: Regulatory, Clinical and Manufacturing Aspects of Biomedical Devices

G. Selvaduray ­ SJSU ­ November 1, 2006

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Features of Program

Balanced interdisciplinary program

Anatomy/physiology, materials, biomechanics, device design, regulations, clinical trials, manufacturing

Emphasis on practical knowledge and skills Case studies Industry speakers Field trips to medical device companies Project/thesis requirement Communications skills seamlessly integrated

Written reports PowerPoint and Poster presentations

G. Selvaduray ­ SJSU ­ November 1, 2006

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Student Response

Classes well-populated (26~40) ~ 40 students signed up for Concentration Students successful in securing internships at companies SJSU students:

Enthusiastic about value and future potential See biomedical devices as a growth area Feel good about contributing to human well-being

G. Selvaduray ­ SJSU ­ November 1, 2006

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Summary/Conclusions

There is a growing market, that will continue to grow for the foreseeable future Driving forces for continued development will exist for the foreseeable future Wireless medical devices will probably grow significantly Inherently multi-disciplinary, with a role for everyone ­ practically

G. Selvaduray ­ SJSU ­ November 1, 2006

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Summary - contd

Highly driven by innovation and technology applications Implantation of electronic circuits into humans will continue to grow Design and service requirements are significantly different Reliability issues are stringent Regulatory approval is necessary The opportunity is there

G. Selvaduray ­ SJSU ­ November 1, 2006

There is a potentially huge market

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Thank You Very Much

[email protected]

G. Selvaduray ­ SJSU ­ November 1, 2006

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