The surgeon prepares the scalpel and checks the instruments; everything is ready to implant a pacemaker. But today, something is different: instead of the complete surgical kit, he takes a needle. A normal one. He fills it with a grain that looks like sand, and injects it into the patient's chest. Three seconds. Done. The pacemaker begins receiving power, the heart beats regularly, no batteries to replace every five years. No scars from incisions. The researchers at WITH Media Lab created a 200 micrometer injectable antenna which is administered like a drug and powers deeply implanted devices.
It operates at low frequencies to avoid overheating tissue and generates 100.000 times more energy than traditional antennas of similar size.
The problem of batteries in plants
Today's medical implants are powered in two ways. The first the offer a battery several centimeters long, surgically implanted into the body, which must be replaced every 5-10 years with a new intervention. The second one It uses a magnetic coil, also centimeter-sized, placed under the skin to collect wireless energy. The problem? The miniature coils only work at high frequencies, which they overheat the tissues limiting the power that can be safely delivered.
“After that limit, you start damaging the cells,” he explains. Baju Joy, PhD student of the group Nano-Cybernetic Biotrek from MIT.
Every year, between 250.000 and 300.000 pacemakers are implanted in Europe (50.000 in Italy alone). Similar numbers are found in the USA, where approximately 250.000 pacemakers and 100.000 defibrillators, with costs in the hundreds of billions of dollars.
Every battery replacement brings risks of infection, patient discomfort, and new healthcare costs. And the miniaturization of medical devices is hampered precisely by the size of the power sources.
How the injectable antenna works
THEantenna developed by Deblina Sarkar's team MIT solves the overheating problem by operating at low frequencies (109 kHz) thanks to a new technology. The device combines a magnetostrictive layer1 which deforms when exposed to a magnetic field, with a piezoelectric layer which converts mechanical deformation into electrical charge. When an alternating magnetic field is applied, the magnetic domains in the magnetostrictive layer deform it like a strong magnet would on a woven metal fabric. The mechanical tension in the magnetostrictive layer causes electric charges to be generated in the piezoelectric layer through the electrodes positioned above and below.
Too complicated? I'll try again. This antenna has a layer that moves like fabric when there's a magnetic field, and another layer that converts this movement into electricity. When the magnetic field changes, the moving layer also moves the electric field, so the antenna generates energy without heating up. Better yet?
“We are exploiting this mechanical vibration to convert the magnetic field into an electric field,” says Joy. The result is a power four to five orders of magnitude higher compared to similarly sized implantable antennas that use metal coils and operate in the GHz range.
Lo study published in IEEE Transactions on Antennas and Propagation in October 2025 demonstrates how it is possible to overcome the technical challenge expressed by the authors themselves:
“Developing an ultra-small antenna (less than 500 micrometers) capable of operating efficiently in the low-frequency band is complex.”
Applications beyond pacemakers
The magnetic field that activates the injectable antenna is provided by a device similar to a wireless smartphone charger, small enough to be applied to the skin like an adhesive patch or kept in a pocket near the skin's surface. The antenna can be manufactured using the same technology used for microchips, allowing easy integration with existing electronics.
“These electronic components and electrodes can be made much smaller than the antenna itself, and would be integrated during nanofabrication,” Joy explains.
Applications go beyond pacemakers and neuromodulators for epilepsy and Parkinson's. A particularly interesting case is continuous glucose monitoringOptical sensor circuits already exist to detect glucose, but the process would benefit greatly from a wireless power source that could be integrated noninvasively into the body. “This is just one example,” says Joy.
“We can take all these other techniques that have been developed with the same fabrication methods and easily integrate them into the antenna.”
The production of antennas can be easily climbed and multiple antennas can be injected to treat large areas of the body. This opens up possibilities for distributed sensor networks or complex therapeutic systems that today would require multiple surgical interventions.
The medical wireless charging market
Il wireless power systems market for implantable medical devices It is booming. Valued at $1,5 billion in 2025, it is expected to reach $5 billion by 2033 with a compound annual growth rate of 15%. Companies like Medtronic, Abbott Laboratories, Boston Scientific and specialized startups such as Nucurrent e Resonant Link Medical are developing products that integrate systems wireless energy transfer.
MIT technology stands out for three crucial advantages: extreme miniaturization (200 micrometers versus the millimeters of current solutions), minimally invasive implant with a standard needle, and absence of tissue overheating thanks to the low operating frequencies.
Injectable Antenna: When Will It Arrive to Patients?
The teacher Deblina Sarkar, group leader Nano-Cybernetic Biotrek and senior author of the study, emphasizes how
“Our technology has the potential to introduce a new avenue for minimally invasive bioelectronic devices capable of operating wirelessly deep within the human body.”
The work leverages 50 years of research into the miniaturization of transistors and electronics, now applying it to the problem of powering systems.
The road to clinical application still requires long-term biocompatibility testing, validation of energy efficiency in real-world scenarios, and regulatory approval from bodies like the FDA and EMA. But all the prerequisites are there: a technology that works, low production costs thanks to established nanofabrication processes, and a growing market seeking solutions to real-world problems.
The needle that replaces the scalpel. A speck that eliminates batteries. Sometimes the future of medicine lies in microscopic things that change everything.
Footnotes:
- The term “magnetostrictive” refers to a physical phenomenon called magnetostriction, which indicates the change in length or deformation of a material, typically metallic and ferromagnetic, when subjected to a magnetic field. ↩︎
