A Wireless Power Transfer Based Implantable ECG Monitoring Device

Abstract

Implantable medical devices (IMDs) enable patients to monitor their health anytime and receive treatment anywhere. However, due to the limited capacity of a battery, their functionalities are restricted, and the devices may not achieve their intended potential fully. The most promising way to solve this limited capacity problem is wireless power transfer (WPT) technology. In this study, a WPT based implantable electrocardiogram (ECG) monitoring device that continuously records ECG data has been proposed, and its effectiveness is verified through an animal experiment using a rat model. Our proposed device is designed to be of size 24 × 27 × 8 mm, and it is small enough to be implanted in the rat. The device transmits data continuously using a low power Bluetooth Low Energy (BLE) communication technology. To charge the battery wirelessly, transmitting (Tx) and receiving (Rx) antennas were designed and fabricated. The animal experiment results clearly showed that our WPT system enables the device to monitor the ECG of a heart in various conditions continuously, while transmitting all ECG data in real-time.Energies 2020, 13, 905 2 of 16 heart represented in a waveform and several features related to the cardiac cycle. Many heart diseases such as ischemic heart disease, arrhythmia, hypertrophy, and cardiomyopathies can be diagnosed by analyzing ECG waveform features [4]. However, the symptoms of arrhythmia are not continuous and appear intermittently. Thus, accurate diagnosis of AF using ECG at the specific time of monitoring would be difficult [5].To increase the accuracy of AF diagnosis, various types of ambulatory ECG monitoring devices in the form of portable, patch, wearable, and implantable to enable continuous recording have been researched and developed [6]. Each type of those devices has different advantages and disadvantages. The portable Holter monitor can measure the most comprehensive 12 leads ECG using several electrodes for 24 to 48 h. While the Holter monitors have been used in hospitals successfully, it is difficult to use them in everyday life due to short operating time and the inconvenience of wires and gel electrodes. The wearable 1 lead patch-type devices have better usability for daily life monitoring, but they also have the disadvantage of using gel electrodes or adhesives despite being non-invasive and leadless. A wearable watch type device such as Kardiaband (AliveCor, USA) for Apple Watch has been proposed recently to enhance portability and mobility. However, those watch-type devices are only capable for on-demand measurement meaning that the ECG measurement is only performed when users initiate the measurement. The ECG measures the potential difference caused by polarization and depolarization in the heart, and thus two electrodes should be placed far from each other to increase the signal quality against noise. This implies the ECG can only be measured when the user touches the electrodes with both hands. Thus, convenience and continuity of measurement are yet to be solved by these device...

New Era of Electroceuticals: Clinically Driven Smart Implantable Electronic Devices Moving towards Precision Therapy

“…Many implanted bioelectronic devices are wired with battery-powered and bulky, which are invasive, causing discomfort to the patient and limiting their usage. As an alternative, Kim et al succeeded in developing a wireless implantable bioelectronic device that can compete with traditional ones [35]. However, these kinds of devices also exhibit some challenges.…”

“…Though current technologies are capable of triggering activities of respective tissues, miniaturized electroceutical devices capable of both monitoring and treating functionality integrated into a single device are of industrialists' and biomedical engineers' current interest [35,40,41]. There is significant interest in developing wireless devices that could monitor, record, and treat neural activity.…”

Design of Powering Wireless Medical Sensor Based on Spiral-Spider Coils

“…Most research on IC-WPT uses it to enhance power transfer and efficiency at different air-gap distances between coils [12][13][14][15]. One study used MRC-WPT to improve the Transfer efficiency for small household appliances and implanted devices [16].…”

Localized Bioimpedance Measurements with the MAX3000x Integrated Circuit: Characterization and Demonstration

“…These details support researchers’ evaluations of these devices and their appropriateness for their specific needs. While the MAX30001/30002 has been available since 2019 and has been utilized for preliminary studies on respiratory [ 27 ] and ECG monitoring [ 28 , 29 ], there are limited explorations of its measurement accuracy for values that are representative of localized tissues [ 30 , 31 ]. Additionally, the MAX30001/300002 supports wide-band multi-frequency measurements (125 Hz to 131 kHz) and tetrapolar measurements (without additional circuitry) in the smallest form factor (8 mm ball-grid array package) of the available bioimpedance ICs in Table 1 .…”