Cooperative dry-electrode sensors for multi-lead biopotential and bioimpedance monitoring

Abstract

Cooperative sensors is a novel measurement architecture that allows the acquiring of biopotential signals on patients in a comfortable and easy-to-integrate manner. The novel sensors are defined as cooperative in the sense that at least two of them work in concert to measure a target physiological signal, such as a multi-lead electrocardiogram or a thoracic bioimpedance.This paper starts by analysing the state-of-the-art methods to simultaneously measure biopotential and bioimpedance signals, and justifies why currently (1) passive electrodes require the use of shielded or double-shielded cables, and (2) active electrodes require the use of multi-wired cabled technologies, when aiming at high quality physiological measurements.In order to overcome the limitations of the state-of-the-art, a new method for biopotential and bioimpedance measurement using the cooperative sensor is then presented. The novel architecture allows the acquisition of the aforementioned biosignals without the need of shielded or multi-wire cables by splitting the electronics into separate electronic sensors comprising each of two electrodes, one for voltage measurement and one for current injection. The sensors are directly in contact with the skin and connected together by only one unshielded wire. This new configuration requires one power supply per sensor and all sensors need to be synchronized together to allow them to work in concert.After presenting the working principle of the cooperative sensor architecture, this paper reports first experimental results on the use of the technology when applied to measuring multi-lead ECG signals on patients. Measurements performed on a healthy patient demonstrate the feasibility of using this novel cooperative sensor architecture to measure biopotential signals and compliance with common mode rejection specification accordingly to international standard (IEC 60601-2-47) has also been assessed.By reducing the need of using complex wiring setups, and by eliminating the presence of central recording devices (cooperative sensors directly sense and store the measured biosignals on the site), the depicted novel technology is a candidate to a novel generation of highly-integrated, comfortable and reliable technologies that measure physiological signals in real-life scenarios.

New biosensors and wearables for cardiorespiratory telemonitoring

“…Instead of using one centralized electronic box, the electronics is spread over the sensing locations, forming socalled 'cooperative sensors' [11] as shown in Fig. 2.…”

“…2. The first benefit of cooperative sensors comes from their connection: regardless of their number, only one contact per sensor with one single unshielded weakly insulated electrical connection is needed for best signal quality of ECG and impedance [11]. This single electrical connection is used for reference potential (ECG and impedance measurements), for current return (impedance measurement), for synchronization and communication between sensors [12], and for automatic wakeup of sensors when placed on the skin.…”

Cooperative sensors: a new wired body-sensor-network approach for wearable biopotential measurement

“…In order to overcome the limitations of the architectures which include a centralized electronics box, a novel design, so-called cooperative sensors, has been presented in [2]. Cooperative sensors use the same underlying electrical circuit as the classical architecture presented in Figure 1.…”

“…Cooperative sensors use the same underlying electrical circuit as the classical architecture presented in Figure 1. However, as shown in Figure 2, the centralized electronics box has been replaced by two types of active cooperative sensors: 1) one reference sensor, which has two contacts with the skin and also plays the role of guard electrode [2], and 2) an arbitrary number of measuring sensors, which have only one contact with the skin. In this configuration each sensor has its own power supply (e.g., a battery) and active electronic components.…”

“…In this paper, we introduce cooperative sensors, a novel sensor architecture which allows overcoming the current limits in integration [2]. We start by presenting the classical methods for multilead ECG measurement.…”