Biophotonics is the science of generating and harnessing light (photons) to image, detect and manipulate biological materials. Biophotonics is used in BIOLOGY to probe for molecular mechanisms, function and structure. It is used in MEDICINE to study tissue and blood at the macro (large-scale) and micro (very small scale) organism level to detect, diagnose and treat diseases in the body.

This presentation will focus on medical applications of light. You will learn what light is, where it is currently used in medicine and how it might be in the future and, how different characteristics of light can cause everything from bioluminescence (like lightning bugs) to heating of tissues to cure diseases to lasers that create micro-explosions in blood vessels.

Today you will learn

  • What is biophotonics?
  • What are some of the many ways light is used in biology and medicine?
  • How can light be used in bioterrorism detection?
  • What are two ways that can light be used to treat stroke?


The goal of this morning's presentation is to introduce you to some of the ways light is used in biology and medicine.

Student Lecture Notes

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1. What is biophotonics?

2. Why are lasers so useful in biology and medicine?


1. Give one example of each of the following types of interactions between light and cells or tissues:

  1. photo-photo
  2. photo-chemical
  3. photo-mechanical
  4. photo-thermal


1. Name one characteristic about antibodies that makes them useful in pathogen detection?

2. What are the two roles of light in the described pathogen detection procedure?


1. What is an ischemic stroke?

2. What is the role of the laser light in the procedure described for breaking up a blood clot lodged in an artery? What is it that actually does the damage to the blood clot?

3. What are shape memory polymers?

4. What is the role of the laser light in actuating shape memory polymers? Describe how this can be used to treat a stroke?

5. What is the major challenge that blood vessel bifurcations pose in the blood clot removal procedure described? What is the proposed solution?

6. What is it about laser light that enables it to deliver so much energy and not damage the blood vessels or other surrounding tissue?


1. Do you know of anyone who has had a medical treatment that has involved light or lasers? If so, what was it?


Speaker Bios

Dr.Duncan Maitland

Associate Division Leader
Medical Physics and Biophysics Division
Physics and Advanced Technology Directorate
Lawrence Livermore National Laboratory

In 1995 Dr. Maitland received his Ph.D. in Biomedical Engineering from Northwestern University where he studied polarized light interactions with tissue. Prior to doctoral research he was employed in the aerospace industry for four years where he performed fiber optic sensor research and managed a group developing fly-by-light flight control systems.

Dr. Maitland has made significant technical contributions to four devices that have been commercialized from LLNL basic and applied research: three technologies that are currently in clinical trials (endovascular ischemic stroke treatment, x-ray catheter for preventing restenosis, and endovascular neurology aneurysm therapy) and one that is in pre-clinical trials (laser-tissue welding). He has 7 patents pending/granted and 30 publications. Active projects include neurovascular catheters (micro-optomechanical actuators), photomechanical transducers/actuators, artificial organs, and polarized light interactions with tissue.

Susan Daly

Susan Daly teaches 11th and 12th grade Biology, Honors Biology, and Advanced Biology at the Athenian School in Danville, California. She has been teaching at Athenian for five years and is currently taking a one year leave of absence to explore a variety of learning opportunities. Susan holds a Bachelor of Science Degree in Biological Science with a concentration in Biochemistry and Molecular Biology from the Australian National University. For the final year of her degree, she participated in a special year-long program where she researched the lethal effects of solar and component ultraviolet radiation on two types of bacteria, Staphylococcus epidermidis and Staphylococcus aureus. After deciding to pursue her passion for teaching, Susan went on to run school health education programs for the National Heart Foundation of Australia before returning to the United States to pursue a career teaching high school science. Susan’s primary goals as a science teacher are to give students the opportunity to experience the exploratory nature of science and to further develop the habits of mind and skills necessary for science.


  • Ablation: The process of removing material from a surface. In photonics applications, the material is typically removed by vaporization (conversion of material in a solid or liquid phase to a gaseous phase).
  • Acoustic: Of or relating to sound.
  • Acoustic Waves (also called Sound Waves): Longitudinal waves - waves which consist of particles vibrating in the same direction as the wave is travelling, creating areas of high pressure (compressions) and low pressure (rarefactions). Compressions are regions along the wave where the pressure and density of the molecules is higher than when no wave is passing. Rarefactions are regions along a longitudinal wave where the pressure and density of the molecules is lower than when no wave is passing.
  • Antibody: Any of a large number of proteins that are produced normally by specialized immune cells after stimulation by an antigen (e.g., body invaders such as viruses or bacteria) and act specifically against the antigen in an immune response.
  • Antigen: Any molecule capable of stimulating an immune response.
  • Artery: An elastic, muscular-walled tube that transports blood away from the heart to all other parts of the body.
  • Bifurcation: The point at which a single object divides into two branches.
  • Biophotonics: The science of generating and harnessing light to image, detect, and manipulate biological materials. Biophotonics is used in biology to study the structure and function of proteins, DNA, and other important molecules. In medicine, biophotonics allows the more detailed study of tissue and blood, both at the macro and micro level, for the purpose of diagnosing and treating diseases from cancer to stroke in less invasive ways.
  • Cancer: A localized growth from uncontrolled cell reproduction, which can (if untreated) spread to other parts of the body.
  • Catheter: A thin, flexible plastic tube.
  • Cavitation: The process by which a localized region of low pressure in a liquid causes the formation of pockets of vapor (gas).
  • Cavitation Bubble: A pocket of vapor produced by cavitation (see above). Cavitation bubbles are usually short-lived and collapse forcefully when they move from the low-pressure region in which they were formed.
  • Chromophore: A chemical that absorbs light of a specific wavelength.
  • Compressive Wave: A longitudinal wave (see "Acoustic Waves" above) propagated by the elastic compression (squeezing and re-bounding) of the medium.
  • Electromagnetic Radiation: Energy, propagated through space or through material media in the form of an advancing disturbance in electric and magnetic fields existing in space or in the media.
  • Electromagnetic Spectrum: The entire range of wavelengths of electromagnetic radiation extending from the shortest cosmic rays, through gamma rays, X-rays, ultraviolet radiation, visible radiation, infrared radiation, and including microwaves and all other wavelengths of radio energy. The shorter the wavelength, the more energetic the radiation.
  • Fluorescence: Luminescence (light emission) that is caused by the absorption of radiation at one wavelength followed by nearly immediate re-radiation usually at a longer wavelength and that ceases almost immediately when the incident radiation stops.
  • Frequency (of waves): The number of oscillations which occur in one second when waves pass a given point. It is equal to the number of wavelengths per second.
  • Hemoglobin: An iron-containing protein in red blood cells that reversibly binds O2 and transports it to body tissues. It also assists in CO2 transport from the tissues back to the lungs.
  • Laser: A device that produces a highly directional and intense beam of coherent light. Light waves are said to be "coherent" when their frequencies are equal and they are in phase, that is, their peaks and troughs are perfectly in step with each other. The word "laser" is an acronym for light amplification by the stimulated emission of radiation.
  • Mechanical: Caused by, resulting from, or relating to a process that involves a purely physical as opposed to a chemical change.
  • Microactuator: A small mechanical device for moving or controlling something.
  • Monochromatic: Light of a single wavelength (or, equivalently, of a single frequency).
  • Occlusion: An obstruction.
  • Optical Fiber: A thin, transparent fiber of glass or plastic designed to confine and direct the propagation of ultraviolet, visible, or infrared electromagnetic radiation.
  • Optics: The science that deals with the genesis and propagation of light, the changes that it undergoes and produces, and other phenomena closely associated with it.
  • Pathogen: A specific causative agent (as a bacterium or virus) of disease.
  • Photo: Of or pertaining to light.
  • Photon: A fixed quantity of light energy. The shorter the wavelength of light, the greater the energy of a photon.
  • Plasma: A collection of charged particles containing about equal numbers of positive ions and electrons and exhibiting some properties of a gas but differing from a gas in being a good conductor of electricity and in being affected by a magnetic field.
  • Shape Memory Polymers: Special plastic materials able to change shape in response to temperature. These plastics have "memory" that allows them to be deformed into a temporary configuration and then be restored to the original parent geometry by applying heat.
  • Stress Wave: Pressure wave. In the context of the photo-mechanical stress waves, the "wave" typically has compressive (positive pressure) and tensile (negative pressure) components.
  • Stroke: The death of brain tissue resulting from lack of blood flow and insufficient oxygen to the brain. A stroke can be either ischemic or hemorrhagic. In an ischemic stroke, the blood supply to part of the brain is cut off because either atheroschlerosis (fatty material accumulates under the inner lining of the arterial wall) or a blood clot has blocked a blood vessel. In a hemorrhagic stroke, a blood vessel bursts, preventing normal flow and allowing blood to leak into an area of the brain and destroy it.
  • Tensile Wave: Low pressure component of a stress wave that pulls material apart (as opposed to compressing or squeezing it).
  • Thrombolysis: The breaking up of a blood clot.
  • Thrombolytic Drug: A drug that dissolves blood clots and restores blood flow in blocked arteries.
  • Thrombus: A blood clot that forms inside a blood vessel.
  • Vaporization: The process of converting material in a solid or liquid phase to a gaseous phase.
  • Vascular: Of or relating to a channel for the conveyance of a body fluid (such as blood of an animal or sap of a plant) or to a system of such channels.
  • Vein: A blood vessel that returns blood to the heart.
  • Visible Light: Electromagnetic radiation detectable by the eye, ranging in wavelength from about 400 to 700 nanometers.
  • Wave: A disturbance or variation that transfers energy progressively from point to point in a medium.
  • Waveguide: A device designed to confine and direct the propagation of electromagnetic waves.
  • Wavelength: The distance between adjacent peaks on a wave.