Wireless Electronic Patches Improve Medical Data and Patient Mobility

The configurability for different biopotential signals is achieved by adding a stage with configurable gain and filter characteristics after the AC-coupled chopped instrumentation amplifier. While the low-power AC-coupled chopped instrumentation amplifier filters the DC electrode offset and flicker noise, and rejects common mode signals, the configurable back-end stage can be used to configure the gain and filter characteristics of the readout frontend for the needs of different bio-potential signals.

Further, the sensor node includes a commercial microprocessor enabling local digital signal processing, a 2.4-GHz radio link and a miniaturized rechargeable Lithium-ion battery. The battery is placed under the electronic components to ensure the local rigidity required for long-term functioning of the electronic components. In addition, the sensor node features a fork-antenna and a snap-on connector (for connection to the electrode). The total size of the flexible core part is 60×20mm2. Two additional snap-on connectors are coupled to the central part with short wires. The complete system is then integrated into textile to form the ECG patch.

Using the ECG Patch

The wireless ECG patch can work in continuous monitoring mode, in which the ECG — or EMG — data is continuously transmitted to the receiver (sampling frequency between 250 and 1000Hz). For cases in which only heart rate information is required, the heart rate can be computed locally on the node and then sent over the air to the receiver. This allows drastic reduction of the use of the radio and hence increases the autonomy of the system. The embedded miniaturized rechargeable battery offers a capacity of 175mAh, which allows for an optimal autonomy of the system varying from one day in continuous monitoring to several days for simple heart rate monitoring.

The Future

Further improvement of wireless sensor systems targets the improvement of autonomy. The idea is to harvest energy from the environment, which then is used to charge an energy-storage device such as a battery. Ultimately, these small autonomous sensors will be linked into a network paving the way to new applications for therapeutics and diagnostics.

This article was written by Els Parton, PhD, Scientific Editor, and Bert Gyselinckx, Director of the Wireless Autonomous Transducer Solutions program, IMEC (Eindhoven, NL). For more information, contact Ms. Parton at This e-mail address is being protected from spambots. You need JavaScript enabled to view it , Mr. Gyselinckx at This e-mail address is being protected from spambots. You need JavaScript enabled to view it , or click here.