External defibrillators that shock hearts out of life threatening arrhythmias are pretty brutal devices. They have to deliver a great deal of electrical energy into the skin so that enough of it reaches the heart, sometimes even to the point of burning the person being treated. The skin is a major barrier to the flow of electric current, as it has an impedance of about 500 kilo ohms per square centimeter, necessitating the use of high power devices. At Rice University students came up with an add-on device to improve the delivery of current toward the heart, potentially resulting in higher chances of rescuing patients while causing little to no harm to the skin.
The Zfib device is a 3D printed pad with 180 microneedles on its bottom side. It interfaces with existing defibrillator electrode pads, transmitting their current through the needles.
After positioning over the skin, pressure is applied to the Zfib in order to push the needles into the dermis. A sensor within the device measures the pressure and illuminates a green indicator light that helps to make sure the Zfib is administered properly. Once that is done, the defibrillation can begin as normal.
In their studies, the team showed that their device reduces the effect of the skin’s impedance by 72%. While more needles would help reduce the impedance even further, their greater number would also make it more difficult to penetrate the skin. The team settled on 180 needles so that almost anyone would be able to apply the Zfib to a stricken person.
The team has already done some impedance testing on a sheep cadaver, and even on one of their own brave team members, using their prototype device.
Here’s a Rice University video about the Zfib:
Project page: Zfib…