A local network of implants uses your body as the wiring

The idea isn’t entirely new. A Food and Drug Administration-cleared pill called Abilify MyCite uses ionic conduction to tell a skin patch it was swallowed. But such systems typically link just two devices, while Abramson’s team wanted SWANS to connect many. The first SWANS component is a wearable hub. It’s a flexible circuit board that reads sensor data, runs decision-making algorithms, and emits voltage pulses of up to 12 volts. The second is a patch of stainless-steel microneedles that delivers those pulses into the body, bypassing the skin’s outermost, poorly conductive layer. The third is a network of syringe-injectable implants, each packing two receiving pads, a transistor switch, a battery, and either a sensor or an actuator such as a nerve stimulator. “We created all of the smarts in the wearable hub,” Abramson said. The wearable has more room and more battery power, so the implants could be kept small and simple. When the hub fires a pulse, it creates a brief electric field that spreads through the tissue in all directions. Every implant within range picks it up, but only the right one(s) react, a bit like people in a crowded room who turn around only when they hear their own name. The team achieved that by making each implant’s transistor switch on only when the incoming pulse crosses a specific threshold. Adding a resistor in front of the transistor raises the voltage needed to flip the switch. Adding a capacitor means the pulse must last long enough to charge it first. By mixing and matching these components, the team made implants that respond only to specific combinations of pulse strength and length. This, the authors admit in the paper, means that voltage thresholds need to be tuned for each body and implant placement. Because SWANS implants are built from passive components, they draw almost no power while listening, extending battery life more than 15 times compared to Bluetooth and NFC. A complete implant with a battery measures 3 by 1.1 by 17 millimeters and fits through a 6-gauge needle. To test the system, Abramson and his colleagues installed it in chicken breasts, skin-on, bone-in pork bellies, and living rats. But SWANS is not a do-it-all in-body communication system, and it likely never will be. The first limitation of SWANS is that it can’t send much data. “We don’t want to send large amounts of data using our devices because we want to create ultra-small, ultra-low-power systems,” Abramson said. SWANS, he argues, is meant to pass key information (like a temperature reading) between body parts, but not much else. The system also hasn’t been tested in large animals or humans yet, though Abramson says preliminary large-animal studies have looked promising. And he already thinks about potential applications. “Right now, neurostimulation and drug delivery are completely separate,” Abramson said. Today, he argues, a person cannot have a drug delivery pump connected with their neurostimulator to allow for combined therapies, even though there are benefits to taking a drug at a specific time in conditions like epilepsy. The strength of SWANS, Abramson argues, lies in how easily it can be integrated with existing implants. “This new communication protocol can be plugged into any of those previous systems,” he said. “Because it’s completely agnostic to the sensor or the actuator that we’re using, we’d be able to create this full network of in-body therapeutics.” Science, 2026. DOI: 10.1126/science.adz5300