Biometric Sensor Addresses Infant Hypoxia, Part Two

Sensors Insights by Dr. Guy M. Hatch, MD


This is the second part of the article on the discovery and invention of a new biometric sensor.  Last week’s described the impetus and sequence of discovery and early development of our Physiology Index (PI) Sensor that detects variations in the absorption of two wavelengths of LED light in skin tissue. 

This article outlines the author’s experience preparing to do this work, as an example to those, especially of the next generation of physicians and engineers in training, seeking to contribute their efforts and talents in this worthy endeavor.  Portions of the full range of technical information needed to discover and invent medical sensors currently live very separate lives in either medical physiology research, or in electronics engineering. 

Formal education in each of these disciplines seldom provides even basic information about the other.  The following provides some insights from history and from personal experience as to how this divide may be bridged.


Prepare To Discover And Invent

This venue focuses on development and application of sensor technology, and speaks the language of the engineering community, but is largely unknown in many areas where an urgent need for sensor innovation exists.  Modern medical and surgical care is deeply dependent upon the extended spectral sensitivity, penetrance, and resolution offered by technology-based sensors and imaging systems.  However, from a physician’s perspective, there remain several areas of critical medical care that could greatly benefit from more diverse and more effective means of detecting and interfacing with human physiology.

Few, if any, of the wonderful life-enhancing discoveries and inventions, which the modern world enjoys, were the product of a single educational discipline.  The history of useful discovery and invention shows that these processes almost always require a wider view than is portrayed and fostered within today’s educational institutions. 

So, how is one to prepare to discover and invent?  Is there a pattern to follow, or is luck the key requirement?  Based on historical experience, a current list of key preparations could include:

  • Study a wide range of subjects;
  • Study beyond the superficial level in key subject areas;
  • Learn and practice supporting skills;
  • Learn and practice the investigation process; and
  • Build stuff

Many useful inventions began as unique combinations of materials, components, or methods that were initially developed for other applications.  Wide-ranging exploration and multiple hobbies and interests, beginning at an early age and continued throughout life, appear to be helpful in preparation. 

Since it is currently difficult for teachers to create individualized, wide-ranging study programs for each student, this process likely needs to be led during a child’s early life by parents, and later continued by the individual person.  Individual-directed study, based on a natural sequence of current interests, is far more enjoyable and possibly ultimately more useful than only teacher-assigned, or test-preparation-targeted study.  Understanding and useful synthesis of processes and concepts is also much more relevant to invention and discovery than memorization and multiple-choice exams.

Therefore, those interested in preparing for discovery and invention need to discipline themselves to study beyond the required depth and breadth.  There are also key skills with which modern discovery and invention in medical and other areas of technology are built.  These include:

  • Reading;
  • Technical writing;
  • Spreadsheet analysis;
  • 3D CAD; and
  • Computer programming.

Beyond formal lecture-based education, advanced and continued learning is almost totally dependent upon reading skill.  Learning to critically read and understand new material is a constant need.

Technical writing is a key method of communication in the scientific world.  It also disciplines the writer to clearly analyze the message.  Credibility is often first gained or lost by the quality of the writing used to describe a new discovery or invention.

Much of today’s scientific, medical, and technical progress is based on mathematics and data analysis.  Facility with computer spreadsheet operations is nearly as important as reading and writing skills in many areas of scientific investigation.

Usually offered through a technical college, skill with 3D CAD software opens the door of virtual design to the inventor.  Mechanical design issues can be worked out much more quickly and inexpensively in 3D CAD than through physical construction, and the resulting computer images can be readily used to portray new designs in communication documents. Some level of skill with computer programming, and with the analysis logic involved, is often key to the processes of discovery and invention in medical sensor technology.


Investigation & Necessity

Novel investigation, of necessity, begins with the “well-known,” and progresses toward the frontier.  Current medical and engineering research literature is filled with reviews of the “well-known;” occasionally combined with bits of new information.  The student of discovery and invention must learn, by careful and wide-ranging study of current literature, to identify the barriers to further progress. 

The goal is to define the desired, currently unavailable information upon which new insights and progress can be based.  Very often, this process ends in dead-ends, beyond which the student cannot progress due to limited current technology, insufficient skills, or limited funding.  However, the process of getting to the dead-end needs to be practiced until it becomes second nature.  Technical writing and other skills can also be practiced and perfected by documenting the research process and conclusions.

Finally, almost no amount of study and thinking through a problem can be of greater worth than building a prototype and doing some testing.  This is where a wide range of knowledge about materials, processes, and components becomes very useful.  Invention is mostly a synthesis of existing pieces; be they materials, mathematics, processes, or designs.  Achieving a useful new function, or being able to discover or sense a previously unknown biologic response, is the target of medical sensor discovery and invention.  Careful thought about expected responses from testing enables deviations to be more readily recognized.  Unexpected results may be due to errors, but may also lead to discoveries if noticed, carefully studied, and fully understood.

It is hopefully evident from the above that effective preparation to discover and invent is not a matter of luck, and that, for various reasons, is also not the prime directive of today’s college and graduate education.  Rather, it is left to the individual student to craft a continuous learning and practice program that will seek out and develop the skills and knowledge listed above – in addition to, and following formal education.

As an interesting and familiar example, X-rays were discovered in November of 1895 by a professor of physics, Wilhelm Conrad Roentgen, as he studied “cathode-ray” tubes, which had recently been invented for electronic applications by Hittorf, Crookes, and von Lenard.  He was exploring the external effects of these devices when an electrical discharge was passed through them.  Taking a wide view, he had previously prepared a cardboard screen painted with barium platinocyanide, which was known to fluoresce when illuminated by UV light.  His landmark discovery was that the powered vacuum tubes caused visible fluorescence of this material even when the path was blocked by materials that block UV light. 

Recognizing this unexpected result, he immediately continued his exploration by using other materials, including his and his wife’s hand to partially, or completely, block the newly discovered rays.  His discovery was enabled by his unique combination of intellect, curiosity, careful and broad-based preparation, and willingness to look thoroughly beyond the obvious and “well known.”

For a more recent example, modern X-ray-based CT scanning was invented in 1959 by Dr. William H. Oldendorf, M.D., a neurologist at UCLA.  His initial 1961 prototype demonstration scanner included a cobalt 60 radiation source, a wind-up alarm clock motor, a phonograph turntable, model railroad tracks, and aluminum and iron nails.  His pioneering data acquisition and analysis methods became the basis of not only CT image generation, but of later MRI, PET, and SPECT image production.

On a personal note, my pre-med, medical, and pediatric residency education was carefully “protected from distraction” from other subjects by my mentors.  I also encountered several criticisms from well-meaning friends and teachers when I asked “non-medical” questions, or spent time studying the design and operation of the monitors, imagers, and other technology instruments they used in their practice.  They felt it important to sternly inform me that I was being trained to be a doctor, not an engineer, and that I needed to decide which path to follow and stick to it. 

As I completed my formal training and entered general pediatric practice, I found my medical colleagues at nearly all levels of specialization largely uninformed about the theory and operation of the medical devices and instruments they had learned to use.  The underlying assumption was that if anything important is to be discovered or invented to enhance the practice of medicine, it would need to come from engineers; not doctors.

My pediatric practice was halted after 21 very enjoyable and successful years.  However, this life change presented me the opportunity to prototype and test my earlier design of a pulse oximeter sensor for use with premature infants, and placed me in close collaboration with excellent mechanical, electronics, and software engineers. 

After 11 months, we demonstrated a very credible engineering prototype reflectance pulse oximeter sensor; ready for the next stage of product design for placement on the chest and abdomen of an infant.  Unexpectedly, testing of this prototype sensor also led to the discovery of previously unreported photonic signal responses; apparently originating in skin tissue, rather than in the blood. 

As part of my work on this project, I needed to hone my technical writing skills, and quickly become proficient with SolidWorks software for 3D CAD mechanical design, LabVIEW software for instrument control and graphic display programming, and Excel spreadsheet operations for data analysis.  This combination of experiences and on-the-job learning, however, enabled me to be gainfully employed for the following eleven years as a mechanical design drafter for ATK, until official “retirement.”

Study and development related to the earlier discovery currently proceeds with a more complete range of knowledge, skills, and experience.  My colleagues and I have recently discovered additional new insights into the dynamics of oxygen metabolism in skin tissue.  Insufficient oxygen, or skin tissue hypoxia, and excess oxygen, or skin tissue hyperoxia, each produce unique, highly robust spectral optical density responses within 5-10 seconds of the change in breathing gas oxygen content. 

We have also recorded a complex pattern of photonic responses apparently due to changes in skin metabolism and antioxidant activity during athletic exertion.  These discoveries, which we hope will become helpful in improving the safety of oxygen delivery in medical care, required far broader education, personal study, and hands-on experience than is currently defined or encouraged by existing graduate education institutions.

While it has been, at times, a challenging, rather lonely, and occasionally criticized journey, it has been a great experience.  Through it, I have learned that the preparation for discovery and invention in biomedical technology does not need to be as poorly defined and misunderstood as it currently is.  The academic subjects involved are challenging, but are understandable with sufficient effort and are not mutually exclusive.  I have also learned that collaboration with highly skilled associates with expertise in areas of formal learning and experience other than my own requires mutual respect and personal humility, and can be both enjoyable and remarkably productive.


And In the End?

In conclusion, I offer the thought that discovery and invention operate upon basic principles that can be taught and learned.  However, these principles may be ignored, or inadvertently suppressed during formal education.  The need to continuously study both within one’s chosen area of professional training and practice, and within a wide variety of complementary areas, remains throughout life.

Because of the limited range of spectral sensitivity of the eyes, and the limitations other human senses, modern medical care needs more than ever before to be supported by new sensors, computers, and communications means to enable the level of success and efficiency in medical care that is needed now and into the future.  My experience has taught me that the steeply siloed and divergent educational paths of today’s graduate education need to tolerate and encourage a much more thorough integration of study and experience, in order to prepare their students for the discovery and invention work needed to achieve tomorrow’s medical care advancements. 

Awareness and useful understanding of as-yet undiscovered phenomena, and invention of the associated tools and methods of future medical care, can likely only be achieved by a highly motivated, broadly educated, hands-on experienced, and humbly collaborative new generation.


About the author

Guy M. Hatch, M.D. practiced as a Board Certified General Pediatrician for 21 years in Logan, Utah.  He then led an R&D team in successful development of a reflectance SpO2 sensor for use with premature infants.  During testing of this sensor, a previously unreported photonic phenomenon was discovered.  For the following eleven years, he was a Mechanical Design Drafter at ATK, Logan, Utah.  He is currently a co-founder and the CTO of Reveal Biosensors, Inc., San Jose, CA, continuing the development of a new biosensor based on his earlier discovery.  He can be reached at:  [email protected] and (435) 757-8081.