Amidst research on flexible electronics, wireless sensors is attractive for researchers that can be worn on the body and gather a variety of medical data. Nonetheless, a similar flexible transmitting device is required, else the sensors would require wired connection to transfer health data.
In a research initiative, researchers from a few academic institutions have collaborated to develop devices to explore the possibilities of wearable, flexible antennae.
Importantly, akin to wearable sensors, wearable transmitters need to be safe for use on the human skin, suitable to function at room temperature, and should be able to withstand twisting, stretching, and compression. However, the flexibility of the transmitter poses a unique challenge: when antennae are stretched or compressed, their resonance frequency changes and they transfer radio signals at wavelengths that may not be in line with the antenna’s intended receivers.
“To address this, if the geometry of an antennae is changed, so will its performance,” stated the lead researcher. The aim is to zero down on a geometrical structure that would allow for movement, and at the same time leave the transmitting frequency unchanged.
The research team carried it out in a stepwise process. In the first step, flexible transmitter in layers created. Using the framework of earlier research, a copper mesh fabricated exhibiting a pattern of wavy lines that are overlapping. This mesh forms the bottom layer touching the skin, and the top layer serves as radiating element in the antennae. Elaborating on the mechanism, the top layer forms a double arch when it is compressed and stretches when being pulled, alternating between these stages in an order of set of steps.