An Introduction to
Biomedical Engineering
Aaron Glieberman
August 3rd, 2010
Bureau of Labor Statistics, U.S. Department of Labor, 2010
Earnings distribution by engineering specialty, May 2008
Bureau of Labor Statistics, U.S. Department of Labor, 2010
Average Starting Salaries: July 2009 survey by the
National Association of Colleges and Employers
Bureau of Labor Statistics, U.S. Department of Labor, 2010
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!
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
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)
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)
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/nonbiological 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 . . .
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
e.g. Musculoskeletal mechanics, trauma injury analysis
12 lead EKG configurations
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
e.g. DNA nanotechnology and computing
Set of fMRI data
Boxes made with “DNA origami”
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
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
-Organ Replacement
-Tissue Engineering
-Animal Locomotion
-Biomaterials
-Drug and Gene Delivery
-Biomechanics
-Techniques in Molecular and Cell Science
-Neuroengineering
-Analytical Methods in Biomaterials
-Molecular and Cell Biology for Engineers
-Biophotonics
-Synthetic Biological Systems/Synthetic Biological Systems in Theory and Practice
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
Case Study: Heart and Lung Machine
Replaces roles of heart and lungs during surgery
Involves biotransport, gas exchange, fluid flow
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
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
Also, coronary – oxygenated blood is supplied to heart cells
Systemic
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
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)
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
Composition of air by volume:
78% nitrogen, 21% oxygen, 0.03% CO2
High O2,
low CO2
High CO2,
low O2
Oxygen saturation
Pressure at tissue
pO2 = 40 mm Hg
Oxygen delivered
Pressure at alveoli
pO2 = 100 mm Hg
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
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)
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
Heart and lung machine, phased out?
Circulation. 2003 Sep 9;108 Suppl 1:II1-8.
Case Study: Neural prostheses
Potential for overlap between chemical, electrical, and mechanical backgrounds
Restoring lost neurological function
Neural prostheses - Neurons
Neurons are a specialized form of cell
Responsible for quick information
transfer in the body
Signaling via chemical and electrical impulses
Neural prostheses – BrainGate
Project based at Brown hoping to restore some activity to quadriplegics
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
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
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
Neural prostheses – Cochlear implants