Heart of the matter

30 October 2007

IMEC’s Eindhoven-based research laboratory has developed a wireless electrocardiography (ECG) patch that can continually monitor heart rate.

Consisting of a wireless sensor node on a flexible, polyimide substrate, and integrated into Lycra, the miniature ECG system (below) measures approximately 6cm x 2cm and can be attached to the body with three, standard, disposable snap gel electrodes.

While the electrodes may be standard, the new ECG device is not. Its flexible structure means it can be fitted anywhere on the body, including curves, and if another patch is placed on an arm or a leg simultaneously, it also operates as an electromyography (EMG) to monitor muscle activity.

The patch operates using a combination of technologies, from a single-channel ultra-low-power biopotential application-specific integrated circuit that monitors ECG signals, to a microprocessor that carries out digital signal processing and a 2.4GHz radio link that sends the information to a receiver connected to a PC or to a data-logger for downloading later on to a computer.

Bert Gyselinckx, IMEC programme director, said the person wearing the patch would need to be 10m from the receiver.

Underneath the electronic components sits a removable and rechargeable lithium-ion battery that powers the device enough to monitor ECG and EMG data continuously for one day, or for several days if only monitoring heart rate.

In the latter mode, the heart rate can be computed on the node itself before being sent to the receiver.

Patchwork: wireless sensor node