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L E T T E R T O T H E E D I T O R Open Access
The development of biomedical engineering as
experienced by one biomedical engineer
Jonathan C Newell
Correspondence: newelj@rpi.edu
Department of Biomedical
Engineering, Rensselaer Polytechnic
Institute, 110 Eighth Street, Troy, NY
12180, USA
Abstract
This personal essay described the development of the field of Biomedical
Engineering from its early days, from the perspective of one who lived through that
development. It describes the making of a major invention using data that had been
rejected by other scientists, the re-discovery of an obscure fact of physiology and its
use in developing a major medical instrument, the development of a new medical
imaging modality, and the near-death rescue of a research project. The essay
concludes with comments about the development and present status of impedance
imaging, and recent changes in the evolution of biomedical engineering as a field.
Keywords: Biomedical engineering, Electrical impedance imaging, Impedance
tomography, Impedance spectroscopy, Biomedical instrumentation
Correspondence
An Electrical Engineer becomes a Biomedical Engineer
I started as an undergraduate Electrical Engineering (EE) student in the early 1960’s.
But at co-op jobs in defense electronics, I decided that EE was not my chosen field. In-
stead, on graduation I joined the Peace Corps doing electric power engineering in the
developing world. I returned to do a Masters in EE, which included a biomedical pro-
ject, part of a surgical research project in trauma. With that degree, I took a draft-
deferrable job in defense electronics. At age 26, I began my career as a biomedical
engineer by rejoining the trauma research project at Albany (NY) Medical College
(AMC). This was a project that brought computer technology to the study and care of
injured patients. It consisted of a dedicated hospital room with then-state-of-the-art
physiological monitoring equipment and computers (terminals to a remote mainframe)
at the bedside. The project was run by a surgeon, Dr. Samuel R. Powers, Jr., and three
faculty members at Rensselaer Polytechnic Institute (RPI) who provided technical expertise.
It was staffed by a Surgical Fellow, a medical technician, and now an electrical engineer.
I thus began to learn the technical aspects of clinical medicine and research with on-
the-job training. The equipment and techniques for physiological measurements at
that time were not sophisticated or well-designed for clinical use. The whole concept
of intensive care was in its infancy, and technical support from commercial equipment
suppliers was weak. Also, trauma was just being recognized as an important problem
by the National Institutes of Health (NIH). Specifically, what came to be called Adult
Respiratory Distress Syndrome (ARDS) was just being recognized, largely due to the
© 2012 Newell; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons
Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution , and reproduction in
any medium, provided the original work is properly cited.
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experience in the Vietnam War, where it was first called “Danang Lung”. Dr. Powers’
group confirmed by measuring lung volume in these patients that the primary problem
involved lung collapse, which was reversed by Positive End-Expiratory Pressure (PEEP)
[1]. Before those years, PEEP was thought to be dangerous –today it is a commonplace.
Using Control Theory to Study the Lung, and a Delayed Payoff
After two years in that job, Dr. Powers advised me to get a Ph. D. in Physiology. He
arranged for my admission to the Albany Medical College, and helped me apply for an
NIH Special Fellowship to support my study. My dissertation evolved from a fortuitous
application of my knowledge of control systems that helped discover an unknown
physiological property of the lung. It had long been recognized that intrapulmonary
shunt caused arterial hypoxemia. I had observed in the Trauma Unit that sometimes
patients would move rapidly from a stable condition to one of high shunt and hypox-
emia. I hypothesized that if arterial hypoxemia could itself make shunt worse, a
positive-feedback system would result that might account for the instability. I designed
an animal experiment to test this, and with the help of a fellow graduate student,
Michael G. Levitzky, we went on to confirm the hypothesis and discover the underlying
mechanism [2].
There was a critical “aha!”moment during the first experiment to test that hypoth-
esis. We had placed an electromagnetic blood flow probe on the left main pulmonary
artery of a dog. When we made that lung hypoxic, we expected to see a decreased
blood flow, but the amplitude of the flow probe signal was unchanged. As we studied
the paper polygraph record, we found by happenstance a premature ventricular con-
traction, followed by a long diastole with zero flow. The diastole showed that the base-
line of the flowmeter had shifted, and masked a prominent retrograde flow in diastole.
The peak inflow was unchanged, but the net flow was in fact reduced by that retro-
grade flow in diastole. I attribute the recognition of that clue to my training to be
skeptical about instrumentation. Many years later, I was in the audience at an electrical
impedance tomography (EIT) conference in Manchester, UK, in 2009 when Marcelo
Amato from Brazil reported finding that the amplitude of the cardiac-frequency pulsati-
lity over the lung fields was not diminished in local hypoxia. He conjectured that it was
due to the mechanism we had discovered, and I was thrilled to direct him to the paper
reporting our original work published 33 years earlier.
Institutional Origins of Biomedical Engineering
I completed the Ph. D. in two years and accepted an appointment as Assistant Profes-
sor in the newly-formed Center for Biomedical Engineering at RPI in 1974. Based on
my two years’experience in the Trauma Center, I began teaching a course called ‘Clinical
Engineering’, a keystone course in a new Clinical Engineering Master’s program. I also
initiated a ‘Biomedical Engineering Laboratory’course, which included the use of experi-
mental animals, a novelty at RPI. I was also appointed Assistant Professor in the Depart-
ment of Physiology at AMC, where I taught respiratory physiology to first-year medical
students for 20 years, thus helping maintain my clinical contacts. And I re-joined the
Trauma Center, now as an Investigator. This background probably contributed to my
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acceptance by the medical community, which has sometimes been an obstacle for biomed-
ical engineers. I’ve been something of a hybrid in many ways, and I’ve found that helpful.
With these beginnings in the early 70’s, the RPI program was one of the first in the
country. Over the next decade, the Center for Biomedical Engineering added faculty,
student enrollment doubled, and the activity became a Department within the School
of Engineering. I ran a research laboratory studying the pulmonary circulation, with
NIH support, and advised a number of Ph.D. and Masters Students. The department
faculty was generally involved with patient-level or organ-level studies, many in pros-
thesis development. Since I started in the clinical environment, I have always kept my
research interests and projects closely allied with current clinical problems. I am some-
times disappointed to read theoretical studies by biomedical engineers that seem need-
lessly remote from clinical use.
Impedance Imaging - an idea whose time may soon come
Around 1985 I was approached by a mathematician who was looking for a simple piece
of electrical engineering data. David Isaacson, Professor of Mathematics, was making a
theoretical study of Electrical Impedance Imaging, and wanted to know what noise level
would be expected in measuring small voltages on the human chest at high audio fre-
quencies. I knew nothing of Impedance Imaging, and told him I didn’t expect it to
work, but I had a lab and we agreed on an experiment that could answer his question.
We found an interested undergraduate, and by the end of the summer, we showed he
was right, it would work, and with roughly what noise levels. From that beginning,
which involved a Radio Shack audio amplifier, a hand-wound variable-tap resistor and
32 jumper wires with alligator clips, it became clear that we needed a multi-channel,
computer-controlled instrument. I had worked in the Trauma Project with Prof. David
Gisser, and when I approached him with the instrument design problem, he responded
with four pages of hand-drawn circuits, and the project was under way [3].
The funding for this project involved a small miracle. The Trauma Unit was still
functioning at this time, funded as a Program Project by NIH. At the last renewal of
this Center Grant, after 22 years of support, I was Principal Investigator of one section,
which proposed to use Impedance Imaging to study the lung with ARDS. The Site Visit
team approved my project with a high priority and intact budget, but disapproved the
whole Center. An NIH administrator named Lee Van Lenten managed to separate the
EIT project from the Trauma Center, assign a new grant number, and change the insti-
tution from AMC to RPI. We had 5 years of full funding, and felt we’d caught a heli-
copter off the Titanic.
Electrical Impedance Imaging, as the name implies, is a technology for forming
images of the interior of the body, based on organs’varying electrical properties, using
data from electrodes applied to the skin around the region of interest. Since it usually
involves a single ring of electrodes and thus images a slice of the body, it is also called
Electrical Impedance Tomography [4]. Some newer instruments operate across a broad
frequency spectrum, and perform Electrical Impedance Spectroscopy. Most instru-
ments measure both the real and imaginary components of the signals, and can repre-
sent the complex impedance. This relatively new field began in about 1986, with initial
work by a group in Sheffield, UK, and us. The European Community funded a
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Concerted Action to support several laboratories in Europe, and we were declared to
be “honorary Europeans”and were invited to the conferences. At that time, we were
the only group in the field from the US. Now there are several.
The technology works by applying small, high-frequency currents (or voltages) to
many (usually 16 to 256) electrodes, and measuring the resulting voltages (or currents).
Most of the European systems used a single current source and multiple voltage mea-
surements, which is relatively easy to build, and works fairly well. We elected to use as
many current sources as we had electrodes (32) and measure voltage on all these elec-
trodes. This system has theoretical advantages over single-source systems, but is a lot
harder and more expensive to build [3,5]. Both designs have existed since around 1988,
and neither has replaced the other to this day. The other important design criterion for
multiple-source systems is whether to use voltage or current sources. Current sources
are less sensitive to high-spatial-frequency noise, but are difficult to implement for
broadband applications, and are intolerant of open electrode connections. We used
current sources for our single-frequency instruments, but moved to voltage sources for
the broadband ACT 4. Prof. Gary Saulnier has since patented a current source design
that is suitable for use in broadband, multiple source applications.
For over two decades, my colleagues and I have been at the cutting edge of this tech-
nology, having to define the problems before we could solve them. It is an exhilarating
experience to be part of a small but world-wide community of workers trying to invent
something completely new. The caveats for those who would pursue such a path are
many, however. There needs to be a balance between developing a promising idea be-
cause it seems to have potential, and identifying an application for which it is truly use-
ful. Clinical utility is a high hurdle. But if you don’t have a vision, it’s hard to do
anything.
Many applications of EIT have been proposed, and tested for feasibility. In Russia, a
system is being marketed for breast cancer detection [6]. But by 2012, most other appli-
cations have languished, and the only other application that appears ready to become
commercial is the monitoring of cardiopulmonary function in acute care patients. An
instrument is being tested by Draeger, based on a 16-electrode design developed in
Germany [7]. Recently, a major US manufacturer of medical instruments has hired
three of our former students, and obtained an NIH grant to develop a commercial clin-
ical instrument. We are collaborating with that effort, which also has clinical colleagues
at Columbia University/NY Presbyterian Medical Center in New York.
Throughout these developments, our EIT project has had intermittent funding from
NIH, and 10 years of support through an Engineering Research Center from the Na-
tional Science Foundation. We have spent around $5 million, and built four generations
of instrument. The last was designed by Dr. Gary Saulnier of RPI, and is a 60-electrode
machine operating from 3 kHz to 1 MHz at 7 frames/sec. It has two plates with radio-
lucent electrodes that are placed on a 3-D mammography machine, allowing simultan-
eous 3-D mammograms and 3-D EIT images to be produced, in-register. We have
collaborated with Dr. Daniel Kopans at Massachusetts General Hospital to study breast
cancer patients, with results that are still being analyzed (Figure 1).
In the 26 years since our first publication, the EIT project has helped educate over
100 students, including several post-doctoral fellows. And four faculty members from
universities in Asia have visited for several months.
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Biomedical Engineering - Challenges and Prospects
While this instrumentation development project was taking place, the field of Biomed-
ical Engineering was changing radically. The discipline of Biomedical Engineering
started with a few random, isolated individuals who took an interest in some aspect of
health care and clinical medicine. They invented devices to solve specific clinical pro-
blems, such as the pacemaker, defibrillator, electrocardiogram (EKG) monitors and
thermodilution cardiac output detectors. The ad-hoc nature of the field is exemplified
by the fact that defibrillators were on the market for many years before defibrillator tes-
ters came along. When they did, it was discovered that all defibrillators delivered only
about 80% of their stored energy. That finding raised the question of which energy to
report to the operator –the stored energy, which is what all early machines reported,
or the more clinically relevant delivered energy. For many years, machines showed
both. Today, you can buy an Automatic External Defibrillator (thanks largely to the
work of Dr. Fred Chapman, one of my students) for a few hundred dollars, and keep it
in your home. Another interesting example is the Pulse Oximeter. It was invented in
Japan, but the inventor never filed a US patent. Many companies scrambled to enter
that market, and the price fell from around $3000 for the early versions to a device you
can buy for yourself for less than $40 [8]. The invention of that device holds a lesson
for any future device designer. For many years, several companies had tried to extract
oxygen saturation information from light shined through tissue. But the presence of
other pigments such as myoglobin made the problem complex, and the signals were
hard to process because they varied a lot with the heartbeat. Hewlett Packard sold a
machine with 8 different light wavelengths to try to separate out just the blood signal.
A man in Japan named Aoyagi realized that those pulse-related signals, which stymied
everyone else, actually contained the solution. The only thing varying was the arterial
blood. If he analyzed only the changes in light absorption, he only needed two wave-
lengths. He used the signal that everybody else tried to work around or eliminate.
Simultaneously with these changes, the technology of medical imaging expanded from
straightforward X-Rays to Nuclear Magnetic Resonance (now called Magnetic Resonance
Imaging because “nuclear”sounded scary), Computed Tomography, and Positron Emis-
sion Tomography. There was always something of a separation between these large
Figure 1 The latest ACT 4 instrument installed adjacent to a Tomosynthesis machine.
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instruments, marketed to radiology departments, and general BME, whose domain was
the entire medical care community. But each informed the other to some extent.
With the formation of organizations such as the Association for the Advancement of
Medical Instrumentation, which went on to organize Biomedical Engineering Techni-
cians, the field began to mature. I believe a critical role was played by the Veterans’
Administration Hospital system, which was quick to introduce the position of Clinical
Engineer to its system. Another early important step was made by Dr. Joel Nobel, who
founded the Emergency Care Research Institute [9], which began evaluating medical
instruments and soon began publishing a journal to support the work of Clinical Engineers.
ECRI has become a clearing house for clinical instrumentation reports of successes and
failures. If you believe that feedback can improve the performance of an engineering sys-
tem, you can appreciate the contribution of Dr. Nobel.
Quo Vadem?
These activities and ones like them defined the field of Biomedical Engineering from
the late 1960’s through the late 1990’s. At around that time, the instrumentation field
became, in many respects, a mature technology with developments better characterized
as incremental rather than groundbreaking. Between the late 1990’s and mid-2000’s,
the bulk of innovative activity moved to cellular- and molecular-level studies generally
characterized as Tissue Engineering. As the basic biology became much better under-
stood, cell culture techniques were refined and taken up by Bioengineers, and the
thrust became to design and build replacement tissues. Starting with skin, but soon in-
cluding blood vessels, neural tissue, and endocrine functions such as pancreatic beta
cells, the nature of the expertise needed by a Biomedical Engineer took a radical
change. Basic cellular level biology, including genomics and nanotechnology have all
nearly merged with biomedical engineering, and the engineers have taken on the prac-
tical goals of building (growing) something useful.
So in recent years, cell culture and other new techniques have become critical parts
of the curriculum for Bioengineering. This clearly promising development will have im-
portant medical applications. But we should not forget that there remain immediate
clinical needs to be met while the longer term solutions are developed. The tragedy of
medicine is that patients continue to become ill before we’ve learned how to cure them.
An eclectic approach to education still seems best.
As I try to extract from this story any message useful to others, the point that seems
to me most clear is that I’m a hybrid who does best working at interfaces. I’ve never
known as much about my colleagues’fields as they do, but by working with colleagues
in different fields on a project that needs expertise in those fields, we’ve gotten much
further than any of us could have gone alone. I’ve often found that the most useful things
I know are things I wasn’t“supposed”to know. So in teaching Biomedical Engineering, I
always tried to teach a diversity of skills, and to teach students to be able to communicate
clearly with folks in other disciplines. That’s not a new message, but I hope to have given
it weight by example.
Abbreviations
EE: Electrical Engineering; AMC: Albany (NY) Medical College; RPI: Rensselaer Polytechnic Institute; NIH: National
Institutes of Health; ARDS: Adult Respiratory Distress Syndrome; PEEP: Positive End-Expiratory Pressure; EIT: Electrical
Impedance Tomography; EKG: Electrocardiogram; ECRI: Emergency Care Research Institute.
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Competing interests
I have no competing interests in this work.
Acknowledgements
I gratefully acknowledge the role of Kenneth R. Foster, who invited this work, and provided much useful guidance
along the way.
My wife, Sigrin T. Newell, provided inestimable support throughout this 45-year journey.
Received: 29 November 2012 Accepted: 10 December 2012
Published: 12 December 2012
References
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of systemic P0
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4. Holder D: Electrical Impedance Tomography: methods, history and applications. London: Institute of Physics; 2004.
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Electrodes in Electric Current Computed Tomography. IEEE Trans Biomed Eng 1990, 37(1):60–65.
6. Cherepenin V, Karpov A, Korjenevsky A, Kornienko V, Mazaletskaya A, Mazourov D, Meister D: A 3D electrical
impedance tomography (EIT) system for breast cancer detection. Physiol Meas 2001, 22:9–18.
7. Information about the Pulmovista instrument being planned by Draeger; can be found at: http://campaigns.draeger.
com/pulmovista500/en/.
8. An example of an inexpensive pulse oximeters for sale to the public; can be found at: http://www.walgreens.
com/search/results.jsp?Ntt=fingertip pulse oximeters.
9. The home page for the Emergency Care Research Institute. Is at: http://www.ecri.org/About/Pages/default.aspx.
doi:10.1186/1475-925X-11-94
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