An Introduction to Biomedical Engineering

1. An Introduction to Biomedical Engineering Aaron Glieberman August 3rd, 2010

2. Bureau of Labor Statistics, U.S. Department of Labor, 2010

3. Earnings distribution by engineering specialty, May 2008 Bureau of Labor Statistics, U.S. Department of Labor, 2010

4. Average Starting Salaries: July 2009 survey by the National Association of Colleges and Employers Bureau of Labor Statistics, U.S. Department of Labor, 2010

5. Why Biomedical Engineering? Promising future developments Improve medicine, save lives Numerous possibilities based upon level of biology and engineering specialty “Hybridization” of skills and knowledge And, of course. . . .BIOLOGY!

6. Types of problems Interface between biological and non-biological materials Design, modeling, and construction of biologically-analogous technologies Understanding and improving upon biological limitations Medical tools and diagnostics

7. Overview Terminology, disciplines, curriculum Case Study: Heart and lung machine Case Study: Neuroengineering - neural prostheses Lab visit: Mathiowitz Lab (If there’s time - Case Study: Biochemical Engineering – tissue regeneration)

8. Overview Terminology, disciplines, curriculum Case Study: Heart and lung machine Case Study: Neuroengineering - neural prostheses Lab visit: Mathiowitz Lab (If there’s time - Case Study: Biochemical Engineering – tissue regeneration)

9. Terminology Biomedical engineering The use of engineering science and math to tackle problems in medicine. When distinguished from “bioengineering,” focuses more on the machine/device/non-biological type of research. Bioengineering Often used interchangeably with “biomedical engineering”. When distinguishing between the two, typically bioengineering tends to refer to engineering using biological substances, often at a higher level of biology than biotechnology. Biotechnology Term that is generally similar to “bioengineering,” but, in comparison, refers most specifically to direct manipulation and use of living biological substances. Also, “biological engineering” and others . . .

10. Disciplines Biomechatronics Aims to integrate mechanical, electrical, and biological parts together e.g. sieve electrodes, advanced mechanical prosthetics Bioinstrumentation Construction of devices for measuring aspects of physiological status e.g. Electrocardiography (EKG), Electroencephalography (EEG), Sieve electrode design Biomaterials Development of materials either derived from biological sources or synthetic, generally used for medical applications e.g. Biopolymers, scaffold material for tissue engineering, coating for transplants Biomechanics Study of mechanics as applied to biological structures 12 lead EKG configurations e.g. Musculoskeletal mechanics, trauma injury analysis

11. Disciplines Bionics Also known as “biomimetics”, using biological mechanisms as an inspiration for engineered technology e.g. gecko grip, velcro, architectural features Cellular, tissue, genetic engineering Manipulation of living cells to replace/improve existing functions or to impart unique function e.g. GMO crops, tissue regeneration Medical imaging Gecko foot and carbon nanotube imitation Visualization of anatomy and physiology, essential for modern diagnosis and treatment e.g. X-ray, CAT, MRI, fMRI, PET, ultrasound Bionanotechnology Combination of nanotechnology and biology Set of fMRI data e.g. DNA nanotechnology and computing Boxes made with “DNA origami”

12. In general Focus on a specific type of engineering to create a desired hybrid between biomedical and other, more established fields Chemical engineering – cellular,tissue engineering, biomaterials, biotransport Electrical engineering - bioelectrical and neuroengineering, bioinstrumentation, biomedical imaging, medical device design, optics Mechanical engineering –biomechanics, biotransport, medical devices, soft-tissue mechanics, biological systems modeling

13. Biomedical Engineering curriculum at Brown Engineering core Basic engineering (statics, dynamics, electromagnetism, thermodynamics, fluid mechanics) Basic chemistry (including organic) Basic math (multivariable calculus, statistics, differential equations) Basic biology or neuroscience (including physiology) Bioengineering courses -Transport and Biotransport Processes-Tissue Engineering-Biomaterials -Organ Replacement-Animal Locomotion-Drug and Gene Delivery-Techniques in Molecular and Cell Science -Biomechanics-Neuroengineering-Analytical Methods in Biomaterials-Molecular and Cell Biology for Engineers-Biophotonics-Synthetic Biological Systems/Synthetic Biological Systems in Theory and Practice

14. Accreditation Accreditation Board for Engineering and Technology (ABET) is a non-profit organization composed of numerous smaller professional societies that evaluates degree programs and awards accreditation if the program matches academic criteria Since BME is a new field, should pay attention to this for the school you attend Important should you wish to become recognized as a professional engineer

15. Case Study: Heart and Lung Machine Replaces roles of heart and lungs during surgery Involves biotransport, gas exchange, fluid flow

16. Blood Average adult human contains 4-5 L of blood Oxygenated blood is red Hemoglobin (Hb), a protein contained within red blood cells, can carry oxygen with its heme groups 4 oxygen-binding sites

17. Physiology of Oxygen Transport – Circulatory system Heart is a pump, a muscle that transports blood through body 4 chambers – left and right atrium and ventricle Flow rate of blood out of heart is called “cardiac output” Two main circulatory paths Pulmonary Pulmonary – oxygen-depleted blood pumped from right ventricle to lungs, blood collects oxygen from lungs and sends it back to left atrium Systemic – oxygen-rich blood pumped from left ventricle, deposits in body tissues, returns to right atrium Systemic Also, coronary – oxygenated blood is supplied to heart cells

18. Physiology of Oxygen Transport – Cardiac Output Cardiac output (Q) can be measured in terms of stroke volume (SV) and heart rate (HR): Q = SV x HR stroke volume is the amount of blood pumped by a single ventricle in a unit of time A reasonable value is 70 mL heart rate is the rate of contractions that the heart makes per minute Normal adult heart rate ranges between 60 and 100 beats per minute Resting cardiac output (Q) = 0.07 L x 100 bpm = 7 L/min Exercising example: SV = 65 mL, HR = 175 bpm cardiac output (Q) = 0.065 L x 175 bpm = 11.4 L/min

19. Physiology of Oxygen Transport – Cardiac Output Blood flow (Q) in a vein/artery or tube derives from the Hagen-Poiseuille formula: ΔP = pressure difference between contraction and relaxation of heart (in kPa) r = radius of tube L = length of tube μ = dynamic viscosity (in N*s/m2)

20. Physiology of Oxygen Transport – Respiratory system Oxygen enters body through nose/mouth Travels down airway into alveoli Gas exchange occurs between alveoli and capillaries driven by pressure gradient High O2, low CO2 High CO2, low O2 Composition of air by volume: 78% nitrogen, 21% oxygen, 0.03% CO2

21. Oxygen saturation Pressure at alveoli Pressure at tissue pO2 = 40 mm Hg pO2 = 100 mm Hg Oxygen delivered

22. Heart bypass surgery Surgery wherein blood flow bypasses the heart and lungs, since operating on an active heart is difficult to accomplish Coronary artery bypass surgery/graft (CAPG) entails grafting vessels from elsewhere in the body to reroute blood flow around blocked regions in the coronary arteries For the past half century, has utilized artificial pumping and oxygenating, which is accomplished by the heart-lung device

23. Heart and Lung Machine First attempted surgery with heart and lung machine in 1951 by Dr. Clarence Dennis First successful surgery in 1953 by Dr. John Gibbon (Perfusionist is trained technician who can operate the heart and lung machine)

24. Heart and Lung Machine, Components Connective tubing – PVC or silicone rubber Pump Roller pump –ciruclating rotor physically displaces fluid through tubing Centrifugal pump – motion of fluid through an impeller (a type of rotor) propels the liquid forward Oxygenator Traditionally, a bubble oxygenator was used, but this has since been replaced by membrane-coated oxygenators

25. Heart and lung machine, phased out? Circulation. 2003 Sep 9;108 Suppl 1:II1-8.

26. Case Study: Neural prostheses Potential for overlap between chemical, electrical, and mechanical backgrounds Restoring lost neurological function

27. Neural prostheses - Neurons Neurons are a specialized form of cell Responsible for quick information transfer in the body Signaling via chemical and electrical impulses

28. Neural prostheses – BrainGate Project based at Brown hoping to restore some activity to quadriplegics

29. Neural prostheses – BrainGate Calibration tests Monkey plays game with joystick, moving arm in response to visual cues As the monkey’s arm moves in the desired direction, brain activity is recorded This firing activity must be decoded to understand the correlation between firing pattern and directional movement

30. Neural prostheses – A different approach Targeted muscle reinnervation (TMR) Relocate nerves from arm to chest Electrode picks up neuron firing in chest Software analyzes firing and drives actuator

31. Neural prostheses – Robotics technology Research on replicating human function Challenges: Linking to biological inputs Sensory feedback Complexity of biology (arm alone is controlled by more than 70 muscles) Controlled strength

32. Neural prostheses – Cochlear implants