The US Defense Advanced Research Projects Agency's (DARPA) "Energy Harvesting Implantable Health Monitoring Solutions" request for information (RFI) looks to create "self-powered energy harvesting medical devices."

Because Uncle Sam doesn't want to go rummaging inside its warfighters' bodies every time a medical implant's battery needs to be changed or charged, DARPA's "Energy harvesting implantable health monitoring solutions" RFI is looking to see if energy harvesting can fundamentally change how implantable devices are powered.

Broadly, energy harvesting means drawing energy from natural sources.

In DARPA's case, it's about harvesting energy from the human body itself through movement, heat, or electrochemical means in order to meet the "increasing demand for minimally invasive, remotely powered, and autonomous medical implants for neurological, cardiac, and other applications."

The main point of contact for this RFI is DARPA program manager Dr. Pedro Irazoqui.

Dr. Irazoqui joined DARPA as a program director in January 2024, and prior to that, he held high level positions at Johns Hopkins University and Perdue University where he specialized "in wearable and implantable wireless medical devices for treating diverse neural pathologies."

He is also the current program lead on at least three other DARPA research programs that we've covered here on The Sociable:

For the purposes of this RFI, the Pentagon's research and development funding arm is specifically seeking information on technologies that address the following:

According to AZO Materials, "Piezoelectrics can harness the biomechanical energy generated by body movements to act as a power source for implantable medical devices."

What's more, "Piezoelectric micropumps are set to revolutionize drug delivery procedures by enhancing precision and accuracy," and "piezoelectric wearable health monitors that continuously track vital signs and detect potential health issues in real time can revolutionize the future of healthcare."

More broadly, mechanisms like piezoelectric and triboelectric "have been demonstrated for efficiently extracting electric power from ubiquitous existed mechanical energy sources like wind, water waves/flows, raindrops, vibrations, human motions, organs, and so on," according to an October, 2021 study published in Nano Energy.

Triboelectric energy is another mechanism that can be harvested from body movements.

A study published in Nanomaterials explains that Triboelectric Nanogenerators (TENGs) "stand out as the biomechanical energy harvesters with the most potential for better biological compliance, high energy conversion efficiency, larger material sources and easier fabrication."

For more real-world use cases, "A self-powered and self-functional sock enabled by TENGs exhibited outstanding energy harvesting efficiency and multiple physiological signals monitoring performance (including gait, contact force, sweat level, et al.)"

And when it comes to thermal energy harvesting, "thermoelectric devices promise to continuously harvest waste heat from the human body to satisfy the energy consumption of personalized healthcare platforms," according to recent study published in Smart Medicine.

Whereas "piezoelectric and triboelectric generators only provide energy periodically depending on the working environment [...] the human body can continuously dissipate thermal energy about 20 mW cm."

To recap, the mechanical energy harvesting for medical devices is concerned with energy generated by the body through movement and heat.

All of these physical energy conversion methods "are based on complex machinery and represent an engineering rather than a biological approach. They are highly dependent on the human/animal physical activity and conditions of the environment," according to a 2015 study published in Bioelectric Medicine.

Another area DARPA is looking at for self-powered energy harvesting medical devices has to do with biofuel cells, which also generate energy from the body, but through enzymes and other electrochemical activities.

According to the Bioelectric Medicine study, "Methods based on the internal physiological activity rather than physical/mechanical activity should be much more reliable for energy harvesting due to relatively stable physiological conditions in a living body.

"Implanted devices used for electrical power generation based on biological inspiration are the most biocompatible and promising [...] Natural biological elements, usually enzymes, interfaced with electrodes in implantable bioelectrochemical systems, typically biofuel cells have illustrated significant importance."

While this particular DARPA RFI is focused on energy harvesting for self-powered "implantable health monitoring solutions," the technology itself could be used to one day power any type of implantable device, not just medical.

The Pentagon, and indeed governments all over the world, are looking to merge humans and machines not just for therapeutic purposes, but for human performance enhancement as well.

This coming era of transhumanism is plowing full-steam ahead in military settings with the goal of creating super-soldiers, but it is also happening in the private sector with companies Elon Musk's Neuralink.

DARPA is in the business of cutting edge research and development for military purposes, but if this RFI ever becomes a fully-funded research program, it could fundamentally alter the implantable device landscape forever while simultaneously making us question what it means to be human.