For cardiac patients such as myself, too much excitement can be a shocking experience. If my heart rate gets too high the implanted defibrillator in my chest can think I’m having a heart attack and give me a friendly remedial shock. But such nasty surprises could soon become less of a concern for people like me – by giving our hearts their very own IP addresses.
Dutch research organisation IMEC, based in Eindhoven, this week demonstrated a new type of wireless body area network (BAN). Dubbed the Human++ BAN platform, the system converts IMEC’s ultra-low-power electrocardiogram sensors into wireless nodes in a short-range network, transmitting physiological data to a hub – the patient’s cellphone. From there, the readings can be forwarded to doctors via a Wi-Fi or 3G connection. They can also be displayed on the phone or sound an alarm when things are about to go wrong, giving patients like me a chance to try to slow our heart rates and avoid an unnecessary shock.
Julien Penders, who developed the system, says it can also work with other low-power medical sensors, such as electroencephalograms (EEGs) to monitor neurological conditions or electromyograms to detect neuromuscular diseases. Besides helping those already diagnosed with chronic conditions, BANs could be used by people at risk of developing medical problems – the so-called “worried well” – or by fitness enthusiasts and athletes who want to keep tabs on their physiological processes during training.
Tied to an Android
IMEC’s technology is not the first BAN, but integrates better than earlier versions with the gadgets that many people carry around with them. IMEC has created a dongle that plugs into the standard SD memory card interface of a cellphone to stream data from the sensors in real time and allow the phone to reconfigure the sampling frequency of sensors on the fly. The associated software runs on Google’s Android cellphone operating system.
However, IMEC has eschewed common short-range wireless standards such as Bluetooth in favour of the so-called nRF24L01+ radio designed by Nordic Semiconductor in Oslo, Norway. “The problem with Bluetooth is that it will increase the power consumption on the sensor side,” says Penders. Using the Nordic system, IMEC’s sensors can run continuously, transmitting every 100 milliseconds, for up to seven days between recharges – a Bluetooth system would barely last a day, Penders says.
In the current design, the ECG electrodes are connected to a small necklace that contains the transmitter and battery. The next step will be to use an ultra-low-power radio transmitter, still in development at IMEC, to improve the stamina and portability of the sensors.
With around 18 million people in the UK living with chronic disease, “telehealth” monitoring like this is the way things are going, says Mike Knapton, associate medical director at the British Heart Foundation. Devices already exist that allow people with pacemakers and defibrillators to send telemetry from their implants via a landline to doctors. But using mobile phones would be the natural next step, he says.