A recently patented innovation related to bioresorbable sensors will have wide application across both government and industry.
Mr. Matthew Dalton, a senior supervisory chemist in the Air Force Research Laboratory (AFRL) Foundational Technology Directorate (RE), and Dr. Tod Grusenmeyer, a senior research chemist in RE, received the patent alongside contract support personnel Kayla Presley and Jack Ly of UES (now AeroVironment). The idea for the patent emerged from their attempts to address an urgent problem impacting warfighter readiness.
Mr. Dalton and Dr. Grusenmeyer have focused much of their work on the human-mission interface and understanding the contours of human performance and aeromedicine. A few years ago, a high number of physiological events were affecting the community of T-6 aircraft pilots at Air Education and Training Command (AETC). At seemingly random times, pilots would lose awareness of what was happening around them and experience various symptoms originally thought to be attributed to hypoxia, creating a very serious safety hazard and grounding the entire fleet.
AETC initially tried to use pulse oximeters – devices that clip onto the fingertip or earlobe – to monitor blood oxygen levels. However, these devices are very susceptible to motion artifacts, and the data gathered during active flights was therefore virtually useless in terms of diagnosing or confirming hypoxia as the root cause of the disorientation.
Mr. Dalton and Dr. Grusenmeyer were familiar with a commercial firm that was working on new tissue-integrating biosensor technology. The technology was about the size of a grain of rice and could be injected directly into the human body to measure tissue oxygen levels with a wearable optical reader, providing more accurate oxygen data less susceptible to motion artifacts.
The two researchers, along with other collaborators in the AFRL 711th Human Performance Wing, believed that using such technology alongside other wearable physiological sensors could help AETC identify the problem affecting its T-6 community. However, during initial conversations with AETC personnel, the researchers found that pilots – along with the acquisition community – were concerned about the ideas of pilots receiving a permanent implant.
The researchers therefore set out to create, in partnership with the commercial firm, a biodegradable version of the technology that would naturally dissolve over time in the body’s skin tissues. They developed several initial technologies based on in-depth investigations into different known biodegradable polymers combined with oxygen sensing chromophores. They also confirmed their accuracy and therefore their potential for sensing and tissue integration in the laboratory.
The patent under consideration is based on synthetic polymers, although Mr. Dalton and Dr. Grusenmeyer are currently pursuing a “sister” patent related to natural silk versions of the biodegradable technology in collaboration with the Kaplan Group at Tufts University.
By conducting in-house chemistry and materials engineering and development, Mr. Dalton and Dr. Grusenmeyer were able to “tune” the technology to last different durations in vivo. For example, the technology can be calibrated to dissolve in a month, or two months, or a year, or whatever timeframe is appropriate to a given use case.
The researchers’ efforts represent a clear example of how initial research trajectories can evolve in unpredictable and unexpected ways. Although the patented technology was not ultimately utilized to help AETC solve its T-6 pilot problem – which, however, resulted in several changes and updates to the T6’s onboard oxygen generation system (OBOGs) – it has yielded a variety of potential applications across government and industry.
In military and civilian medical care, it can be used to assist with critical care or battlefield trauma care by providing direct measurement of tissue oxygen levels, e.g. in limb ischemia due to trauma or disease. Much of the researchers’ work was conducted during the Covid-19 pandemic, and it became obvious the technology could also prove useful for monitoring tissue oxygen levels in Covid patients. Because of its wide applicability across the medical field, the bioresorbable sensors have enormous commercialization potential.
In fact, the researchers’ efforts have generated four other patent applications, with more applications very likely to follow. Three of these applications pertain to oxygen and biomarker sensing microneedle technology, which will markedly decrease the invasiveness of the injection procedure. This technology allows the same optical detection of tissue oxygen in the interstitial fluid less than one millimeter into the skin. It includes a completely removable microneedle patch with optical properties tuned to allow the optical excitation and read out necessary for biosensing. In addition, it can accurately detect important sodium and potassium biomarkers.
The effort has also resulted in several publications in academic journals focused on materials science and medical sensors, which has allowed the researchers to disseminate their findings to a broader community and spur further innovation and discovery.
The researchers’ patent application was facilitated by their local Office of Research and Technology Applications (ORTA). DAF ORTAs conduct outreach related to technology transfer and facilitate the development of formal technology transfer agreements, including patent licensing agreements, to ensure the protection of DAF’s intellectual property interests. The DAF Technology Transfer and Transition (T3) Program Office provides DAF ORTAs with training and guidance, and it also performs ORTA services for DAF laboratories lacking their own ORTA.
United States Patent and Trademark Office Patent #12,648,720
About AFRL
The Air Force Research Laboratory, or AFRL, is the primary scientific research and development center for the Department of the Air Force. AFRL plays an integral role in leading the discovery, development, and integration of affordable warfighting technologies for our air, space, and cyberspace forces. With a workforce spanning across nine technology areas and 40 other operations across the globe, AFRL provides a diverse portfolio of science and technology ranging from fundamental to advanced research and technology development. For more information, visit afresearchlab.com.