Innovative antennae may signal a 'new wave' in health care provision

Compact, wireless and power efficient body sensors that allow doctors to monitor illnesses and injuries remotely are a step closer thanks to new research.

The use of biosensors attached to the body for health monitoring is not new. However, antennas that enable such devices to be linked together efficiently on a patient’s body without wires are currently too uncomfortable to wear for a long time because they need to be large in order to maximise the strength of the signal being received. They can be reduced in size but this leads to the antenna being less efficient, meaning that the battery powering the device has to be recharged more frequently.

Experts in antennas and bioelectromagnetics at Queen’s University Belfast (QUB), with funding from the Engineering and Physical Sciences Research Council (EPSRC), have developed new types of antenna that get round these limitations.

Their work could revolutionise the way patient care is provided, making unnecessary visits for tests and check-ups a thing of the past. Instead, biosensors could gather data on heart rate, respiration, posture, gait etc, transmitting this information by radio signal to a control unit also on the patient’s body. The data could then be accessed by doctors via the internet or mobile phone, for example.

The new types of antenna are the first in the world to deliberately harness the so-called ‘creeping wave’ effect. With a conventional on-body antenna the majority of the signal is transmitted either away from the patient or inwards, where it is absorbed by the patient’s body which weakens the signal. The rest of the signal, though, hugs the skin’s surface and ‘creeps’ round the body where it is picked up by the control unit.

However, only a small amount of the signal behaves in this ‘creeping’ way and so its overall strength has to be increased to allow enough of it to reach the control unit. Although traditional antenna designs can be used, they are physically large and typically protrude up to 4cm from the body surface for the frequency bands used by systems such as WiFi. Reducing the size leads to poor system efficiency.