Implantable Biocompatible Lasers!

Russ Hobbie and I discuss lasers several times in Intermediate Physics for Medicine and Biology. For instance, Homework Problem 6 in Chapter 14 is:

Problem 6. The left side of Fig. 14.1 shows the emission of a photon during a transition from an initial state with energy E_i to a final one with energy E_f . Usually the Boltzmann factor ensures that the population of the initial state is less than the final state. In some cases however, when the initial state is metastable, one can create a population inversion. Photons with energy hν corresponding to the energy difference E_i − E_f can produce stimulated emission of other photons with the same energy, a type of positive feedback. Lasers work on this principle. Suppose a laser is made using two states having an energy difference of 1.79 eV. What is the wavelength of the output light? What color does this correspond to? Lasers have many uses in medicine (Peng et al.2008).

I thought I was familiar with most biomedical applications of lasers, until I read the recent article by Tami Freeman in medicalphysicsweb.org.

Sep 27, 2017

Implantable biolasers line up for therapy, monitoring

Biolasers -- miniature implantable lasers made of biocompatible materials -- are the subject of increasing research interest. Such lasers, which offer narrow emission linewidth, high coherence and high intensity, could enable novel imaging, diagnostic and therapeutic applications, as well as real-time physiological monitoring of temperature or glucose levels...

Implantable lasers made of biocompatible materials? Wow! The article concludes

...The researchers concluded that the availability of biocompatible and biodegradable microlasers made from materials approved for medical use or substances already present in the human body may open new opportunities for light-based diagnostics and therapies, as well as basic research.

“One of the first applications could be sensing and diagnostics,” [Marjaž] Humar [from the Jožef Stefan Institute] told medicalphysicsweb. “For example, the biolasers could be functionalized to be sensitive to glucose. A person having these lasers implanted into the skin would simply measure their glucose level by reading the laser output with a small optical reader.”

Not only is this article fascinating, but also it reminds me: have you been keeping up with medicalphysicsweb? Anyone interested in medical physics should read it regularly. Medicalphysicsweb is a community website from IOP [Institute of Physics] publishing. The English IOP is similar to the USA’s American Physical Society, supporting physics education, research, and industry. Tami Freeman does a superb job editing medicalphysicsweb. To hear more about her story, see https://ioppublishingcareers.org/meetourpeople/tamifreeman.