The ability to access physiological data is desirable not only to the consumer but to the military for a number of reasons. Monitoring and recording the physical condition of pilots or soldiers in the field can enable a better understanding of surroundings, provide an added degree of safety and help define mission parameters. To be practical, however, such a monitoring device has to be compact, unobtrusive and easy to use.
According to AFRL Principal General Engineer Dr. Ben Leever, the laboratory has been researching these technologies for a number of years, primarily focusing on non-invasive approaches such as skin patches. It became clear, however, that this approach may not be ideal for Air Force mission requirements.
“We have seen that there are limitations to these non-invasive approaches and that we could potentially get much higher quality data from approaches that are minimally invasive,” said Leever.
To further investigate an alternate approach, in 2018, AFRL entered into a cooperative research and development agreement with Profusa Inc., a company specializing in the development of biosensor technologies. Through an investment from both the Defense Advanced Research Projects Agency as well as the private sector, the San Francisco-based startup researched and developed minimally-invasive physiological sensing technologies over the past decade.
Its novel approach involves a two-part monitoring system in which tiny flexible hydrogel sensors are injected under the skin, integrating into the surrounding tissue. A lightweight optical reader worn on the skin detects a fluorescent signal from the embedded sensors, resulting in a data readout that can be sent to a smartphone or other data collection device.
According to AFRL Scientist and Program Manager Dr. Jeremy Ward, this minimally invasive approach provides reliable and repeatable data, while solving the foreign body response challenge that is common with most biosensors that are embedded under the skin. This response occurs when the body defensively builds up collagen around a foreign object. Such an occurrence greatly decreases the embedded sensor’s effectiveness at providing reliable information about a human’s biochemistry.
“With this solution, the biosensor in the body is the consistency of a contact lens and is smaller than a grain of rice,” said Ward. “While there are no electronics that go inside the body, the biosensor is engineered with specific molecules that respond to specific wavelengths of light. Depending on the composition of those molecules, their optical response changes based on the local concentration of oxygen, glucose or other analytes in the body.”
This idea was promising to AFRL researchers, but further maturation was necessary to enable its use in military applications. To take the technology to the next level, AFRL recently partnered with NextFlex, a consortium of government, industry, and academic institutions dedicated to advancing the manufacturing of flexible hybrid electronics within the United States.
Through an AFRL investment, the NextFlex team worked with Profusa to make improvements to the sensor patch worn on the skin, adding flexible characteristics and bringing it to a state of maturity at which it could undergo testing for defense applications.
“NextFlex has outstanding capabilities in flexible electronics that have enabled acceleration of our manufacturing plans,” said Dr. Oxana Pantchenko, Profusa Wearables Technologies lead.
Ward says that through engaging the NextFlex team, AFRL was able to help reduce development and manufacturing risk for Profusa. By bringing in NextFlex and providing funding for the next level of development, AFRL was able to ensure the expertise and resources were in place to enable the project to move forward across the Department of Defense.
“We were confident that NextFlex possessed the expertise and infrastructure to do the work, and our investment removed that manufacturing uncertainty for the startup, Profusa,” said Ward. “It is great that we were able to help enable a strong developmental and supply chain partnership between NextFlex and Profusa.”
Ward said an added benefit was that Profusa was able to remain highly involved in the development process, working collaboratively with NextFlex and AFRL to share ideas and arrive at the best solutions in the quest for a product that can ultimately benefit the warfighter and the consumer alike.
Currently, the NextFlex team is delivering a small-scale production run of devices to AFRL and Profusa. If successful, the team will be capable of delivering much larger volumes in the near future.
“This approach to reliably sensing the biochemistry of a human has the potential to be transformative,” Ward said. “Our investment and partnership with NextFlex have significantly risk-reduced and enabled the appropriate manufacturing scale to enable expanded testing and evaluation of this technology for use in both defense and commercial applications.”
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