The pacemaker is said to harvest energy wirelessly from radio frequency radiation transmitted by an external battery pack. In the prototype, the wireless power transmitter can be up to a few centimetres away.
Pacemakers use electrical signals to prompt the heart to keep a steady beat, but traditionally they’re not implanted directly into a patient’s heart. Instead, they’re located where surgeons can periodically replace their onboard batteries with minor surgery and their electrical signals are transmitted to the heart via wires called ‘leads’.
Some of the common problems with this arrangement are complications related to the leads, including bleeding and infection. The researchers claim the prototype wireless pacemaker reduces these risks.
They also state that the form factor of other recently introduced pacemakers limit them to a single heart chamber and they cannot provide dual-chamber or biventricular pacing. In contrast, battery-less, lead-less and wirelessly powered microchips can be implanted directly to pace multiple points inside or outside the heart.
“This technology brings into focus the possibility of achieving the ‘Triple Crown’ of treatment of both the most common and most lethal cardiac arrhythmias: external powering, wireless pacing and — most importantly — cardiac defibrillation,” said Dr Mehdi Razavi, director of clinical arrhythmia research and innovation at THI.
The chip at the system’s heart is less than 4mm wide and incorporates the receiving antenna, an AC/DC rectifier, a power management unit and a pacing activation signal. The chip receives power using microwaves in the 8 to 10GHz electromagnetic frequency spectrum.
The frequency of the pacing signals produced by the pacemaker can be adjusted by increasing or decreasing power transmitted to the receiving antenna, which stores it until it reaches a predetermined threshold. At that point, it releases the electrical charge to the heart and begins to fill again.