Sometimes smaller really is better. Think of it this way: The human body is made up of trillions of cells, smaller than the eye can see, constantly undergoing complex interactions. Yet when it comes to medicine, almost everything we do—every intervention we take into that system—happens at a much greater scale. It's a fundamental mismatch, but for thousands of years of medical science has managed to work within it. Pretty well, in fact.

But what if we could more precisely interact with the body at the cellular level? You've probably already heard of nanotechnology, the buzzword-y innovation that's brought you everything from super-fast microchips to stain-resistant pants, thanks to manufacturing processes that manipulate matter at the very smallest of scales. (Nanometers are billionths of a meter: We're talking about actually moving atoms around.)

Nanotechnology as a concept has been around since the middle of the last century, and while we haven't yet perfected some of its more far-out advances (think subatomic, self-building machines), nanotech is definitely mainstream. The electronic device on which you're probably reading this is smaller and faster thanks to nanotechnology.

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So it stands to reason we'd want to take what we've learned about nanotech and apply it to ourselves. One way of thinking about it is that we're shrinking our tools to fit the building blocks of the human body. With the right-size tool, we can perform subtler and more intricate interventions in this meat machine we're still working to understand.

That's the promise of nanomedicine, an emerging and interdisciplinary field. It's still very early stages in working on the body at this scale. Much of the science is being worked out as we speak, undergoing the slow translation from theory to practice. Almost none of it is actually being used in humans—yet. But researchers see a lot of potential, from cancer treatments to targeted drugs to nano-scalpels used to repair individual damaged cells. There's the possibility of vastly improved disease diagnoses and biological sensors. Tissue engineering. And, of course, there's still that sci-fi vision of subatomic robots ready to cure whatever ails you.

Researchers see such a bright future because, right now, the field is wide open. "It's a dimension that we really haven't thought about until recent years. Properties get very interesting on the nanoscale, and that's why we want to study it," says Carly Filgueira, a research associate at the Houston Methodist Research Institute.

Filgueira works with Alessandro Grattoni, head of the department of nanomedicine, on a device designed to improve drug delivery. Every drug out there, she explains, has a clear purpose and benefit, whether it's pain relief or treating mental illness or controlling diabetes. Every drug, too, has side-effects, some of which can be debilitating. "Nanotechnology is one tool that we're trying to harness to maximize the benefit of a drug while minimizing the off-target effects," she says.

In this scenario, a pill or an injection, say, is a relatively unsophisticated piece of drug-delivery technology. It requires a diligent patient to administer it as prescribed, over a set time period. It's easy to forget to take a pill, or to stop taking it when it seems to have done its job. Filgueira mentions hormone therapy, which can put patients on an emotional roller coaster thanks to repeated testosterone injections. The Institute's device could, by contrast, deliver hormones in a smoother, sustained way. That's also valuable for preventive medicine—for patients at higher risk of HIV exposure, for example.

Filgueira describes a device that doesn't sound like science-fiction. Picture a small reservoir filled with whatever drug it's meant to deliver. (Filgueira describes it as "drug agnostic," open for whatever applications might arise.) There are no pumps or valves, no moving parts. There's no power supply. The device will passively deliver its payload in a sustained, linear way.

It works via what's called a nanochannel delivery system (nDS): Nanochannel membranes are custom-engineered based on the size of the drug molecules being released. Once the device is implanted beneath the skin, the drug begins to diffuse across the membranes into the patient's body. "The size of the nanochannel is what's restricting the drug," Filgueira says. "Because of these advances in lithography"—advances brought about by the highly competitive semiconductor industry—"we can really meticulously change the size of the nanochannel all the way down to 2.5 nanometers." That's really, really small.

"Because we're getting the sustained release profile, we're able to avoid the severe toxic side effects that can be associated with poor quality of life," Filgueira says. Altering the nanochannel allows researchers to control how fast the drug is delivered; in pilot studies they've set it to release over 21 days, but further research is planned to stretch that to 60 days. (The National Institute of Allergy and Infectious Diseases has provided a multi-million dollar grant toward that goal.) Besides mitigating side effects, such timed-release devices could be a boon to people who don't have access to regular medical care. The technology could also lead to totally novel treatments that aren't yet envisioned.

First, though, it actually has to be tested in humans. Filgueira describes a simple implant procedure after which patients would be monitored until it's time for their next refill; she'd like to see human testing in that vein in the next five years. The device is also expected to be tested during three of ten research projects planned aboard the International Space Station over the next five years.

That's a relatively short timeline in a medical field where advances often take decades. And in nanomedicine, an area where much of the fundamental research is just now taking place, it's work that's refreshingly close to helping real, live people. (Even if it's not whirring nanomachines coursing through someone's bloodstream, fighting off disease.) It could prove to be one of the earliest realizations of nanomedicine's lofty potential. That said, the future isn't here just yet. "There's a lot of work to be done, of course," Filgueira says. "But we're here, and we're ready to do the work."