I've got a new antenna in my wrist band

The extremely flexible antennas contain silver nanowires and can be incorporated into wearable health monitoring devices. Credit: Amanda Myers

Sensors keep evolving extending their range of application. One area where lot of work is going on is the one of body sensors to track our health status. They can be used to monitor pathological conditions, the body reaction to a cure or to a truing session.

In particular a lot of work is being done, at EIT ICT Labs as well, in the area of proactive health care and well being. In this sector there is a big potential market since people are very much interested in keeping up to shape, and there is a corresponding social interest since it is a fact that by taking care of our health to prevent chronic pathologies we are saving a lot of money collectively.

The problem with health monitoring is that you are not willing to be encumbered by annoying devices. The marketeers are well aware of this and they try to offer products that are perceived as fashionable gadgets, cool to wear.

One of the downfall in these products, that area basically wearable sensors, is the antenna. Indeed technology has found ways to create tiny circuits that can be embedded in fabric, so that you can wear them. But the antenna has remained a crucial component that needs specific geometry to work properly (which also means to decrease the power consumption, an important aspect in wearable sensors...).

Now a team of researchers at the North Carolina State University has found a way to create an embeddable antenna that can be stretched and bended but that will return to its original shape. This ensures a good transmission signal.

To do this they have used nano wires positioned in the desired geometrical pattern (each pattern is optimal to transmit/receive at a specific frequency) and then they poured a polymer on it. The polymer can be rolled, stretched, bended in any way but then it returns to the original shape and the nano wires regain the original pattern.

The researchers have found that the frequency changes as the antenna is stretched but the changes remain within a specific range so the receiver can still work out the signal. Interestingly, the frequency change is a function of the stretching value so it is actually possibile to use the change in frequency as a measure of the stretching, transforming the antenna into a sensor, which might be of interest in certain applications.

Author - Roberto Saracco

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