Electromagnetic Interference Detection Research Articles

CI-452764-2 HIGH-POWER CHARGERS FOR ELECTRIC VEHICLES: ARE THEY SAFE FOR PATIENTS WITH PACEMAKERS AND DEFIBRILLATORS?

Electromagnetic interference (EMI) poses a risk to patients with cardiac implantable devices (CIEDs) and can result in device malfunction including pacing inhibition or inappropriate shock therapy. Such EMI sources are ubiquitous in the modern world. Battery electric vehicles (BEVs) represent such a potential EMI source. We have previously investigated the EMI risk of driving eCars and found that the largest electromagnetic field is located along the charging cable. New high power chargers deliver higher currents (facilitating rapid recharging), potentially associated with greater electromagnetic fields and higher risk for clinically relevant EMI. This present study aims to evaluate this EMI-risk for CIED patients while using high-power chargers for electric vehicle A consecutive group of 130 patients with a range of CIEDs were recruited to participate. After a complete device interrogation each had their device programmed to optimise EMI detection with ensured ventricular pacing and ICD therapies were disabled. Under continuous 6-lead ECG monitoring each patient then plugged in and charged four different BEVs (Porsche Taycan Turbo, VW ID3 pro, Tesla Model 3 and Audi e-tron 55 Quattro) in addition to a ‘dummy’ eCar (which permitted the maximal charging power flow of 350kW) with the charging cable placed directly over the device (Figure 1). During charging both the magnetic field and electric field was measured. A further complete device interrogation was then performed to evaluate for spontaneous reprogramming and tachycardia detection. In total 561 separate charging events were performed by 130 patients with the four eCars and one dummy car. There were no incidences of EMI, specifically there was no pacing inhibition due to oversensing, no spontaneous reprogramming and no tachycardia over-detection. This results in a patient-based risk of 0% (95% CI; 0% - 2.8%) and a charging event-based risk of 0% (95% CI; 0% - 0.6%). The use of electric cars with high-power chargers by patients with cardiac devices appears to be safe with no evidence of clinically relevant EMI. Reasonable caution, by minimising the time spent in close proximity with the charging cables, is still advised as the occurrence of very rare events cannot be excluded from our results.

High-power chargers for electric vehicles: are they safe for patients with pacemakers and defibrillators?

Battery electric vehicle (BEV) sales and use are rapidly expanding. Battery electric vehicles, along with their charging stations, are a potential source of electromagnetic interference (EMI) for patients with cardiac implantable electronic devices (CIEDs). The new 'high-power' charging stations have the potential to create strong electromagnetic fields and induce EMI in CIEDs, and their safety has not been evaluated. A total of 130 CIED patients performed 561 charges of four BEVs and a test vehicle (350 kW charge capacity) using high-power charging stations under continuous 6-lead electrocardiogram monitoring. The charging cable was placed directly over the CIED, and devices were programmed to maximize the chance of EMI detection. Cardiac implantable electronic devices were re-interrogated after patients charged all BEVs and the test vehicle for evidence of EMI. There were no incidences of EMI, specifically no over-sensing, pacing inhibition, inappropriate tachycardia detection, mode switching, or spontaneous reprogramming. The risk of EMI on a patient-based analysis is 0/130 [95% confidence interval (CI) 0%-2%], and the risk of EMI on a charge-based analysis is 0/561 (95% CI 0%-0.6%). The effective magnetic field along the charging cable was 38.65 µT and at the charging station was 77.9 µT. The use of electric cars with high-power chargers by patients with cardiac devices appears to be safe with no evidence of clinically relevant EMI. Reasonable caution, by minimizing the time spent in close proximity with the charging cables, is still advised as the occurrence of very rare events cannot be excluded from our results.

A single-coil-based method for electromagnetic interference reduction in point-of-care low field MRI systems

One of the main challenges for point-of-care (POC) MRI systems is electromagnetic interference (EMI), since such systems are intended for use outside conventional Faraday-shielded rooms. Many methods have been proposed based on EMI detection via sensors external to the MRI system, followed by different types of signal processing to reduce artifacts in the image. Although these methods can be very effective, they do increase the complexity of the overall system, and introduce more potential failure points for systems designed for challenging environments. In this work we introduce a new method that does not require external sensors, but rather uses the “MR-silent” mode of an RF coil to detect the EMI, followed by simple subtraction from the signal from the “MR-active” mode. This method can be performed post-acquisition if there are two receive channels available, or as demonstrated here can operate with a single-channel receive detection system with the addition of a simple passive 180° power splitter/combiner into the receive chain. Proof-of-concept in vivo results show that a reduction in the standard deviation of the EMI up to ∼ 97 % is possible, with average values ∼ 90 %.

A Microcontroller Unit-Based Electromagnetic Bandgap Control Scheme: Application for Enhancing Isolation in an Antenna Array and the EMI Scanner System Speed Thereof

This article presents an adaptive electromagnetic bandgap (EBG) scheme based on a microcontroller unit (MCU) for reducing the mutual coupling in an antenna array designed for electromagnetic interference (EMI) scanner system enhancement (e.g., scanning speed, lower weight and size, and maintenance). For the first time, the EBG is configured via an MCU to enable the finest control of the equivalent lumped elements of the EBG, realizing optimal isolation between/among the antennas at very close distances (1.2 mm $= 0.05\lambda $ at 10 GHz), which typically translates into longer distances between/among the antennas and/or more EBG elements (examples are referenced for comparison). The desired optimal isolation performance is realized by the EBG scheme combined with varactor diodes under the control of the MCU (later the microcontrolled EBG or MC-EBG) referencing a database compiled from the simulation results. In a simulation, the optimal isolation was found to be −58 dB ( $S_{21}$ ) between two small-loop antennas (later the 2-SLA prototype) on a high-permittivity substrate ( $\varepsilon _{r} = 12.8$ , 4-mm thick). For the 4-SLA prototype devised here under identical substrate conditions, the optimal isolation points were found to be −30 dB ( $S_{21}/S_{31})$ and −38 dB ( $S_{41}$ ). During the measurements, when compared under a EBG-standalone tuned isolation at 10 GHz, the measured isolation of the ultimately selected 4-SLA prototype was found to be better by more than 29 dB (−7 to −36 dB) between the closest SLAs ( $S_{21}/S_{31})$ and by more than 35 dB (−18 to −53 dB) between the farthest SLAs ( $S_{41}$ ) at the same frequency. The accordant S-parametric results from both the simulation and the measurement are supported by the simulated $H$ -field distribution (dBmA/m). The $H$ -field from one SLA to the others was found to be reduced by more than 30 dB with the MC-EBG activated (MCU ON), and this is compared with the value of 13 dB from the tuned EBG-standalone case (MCU OFF). The final 4-SLA prototype was deployed in an actual 1 mm over-the-air (OTA) near-field EMI test at 10 GHz. The final field application results prove an enhancement in the EMI scanning speed (few hours versus few minutes) with a very low error rate (clear EMI detection), with the ultimate goal of the MC-EBG thus successfully accomplished.

THE CHANGE OF CARDIOSTIMULATION DEVICE PROGRAMMING DUE TO DETECTION OF ELECTROMAGNETIC INTERFERENCE

The study deals with the interdisciplinary topic of the electromagnetic compatibility of the cardiac implantable electronic devices that are used in patients with a defect of heart conduction system. We are focusing on the detection of disturbing signals on electrodes of cardiostimulation device and its interpretation. The detection of electromagnetic interference (EMI) is related to electrode choice, device placement, its configuration and programming. The aim of the study is the analysis of the pacemaker response in the presence of an external source of the disturbance fields. We point to possible risks of its interaction and discuss mechanisms that can influence the pacemaker sensitivity to EMI. Due to improper signal detection, the device programming changes can occur. We present an experiment of the exposure of the cardiostimulation system to a low-frequency harmonic interference signals and finally we analyse similar clinical episode and discuss proper functioning of the pacemaker.

An Algorithm for Detection of Electromagnetic Interference in High Frequency Radar Range-Doppler Images Caused by LEDs

This paper focuses on the impacts that noise generated by the light emitting diodes (LED) have on high-frequency surface wave (HFSW) radars. Initially, the measurements of the electromagnetic interference caused by the LED lights were conducted in an anechoic chamber, in order to eliminate the influences of other interference sources. It was determined that the most significant interference in the HF range is generated between 6 and 12 MHz. Next, the HFSW radar measurements in real field conditions were conducted at an operating frequency of 6.7 MHz. The LED influence on the HFSW radar was analyzed using the range-Doppler (RD) images. A novel algorithm based on the image segmentation and image processing methods for the automatic detection of the LED noise in the HFSW radar RD image is proposed. The proposed algorithm was experimentally validated using the data obtained from the HFSW radar sites located in the Gulf of Guinea. It was concluded that the proposed algorithm is capable of identifying and eliminating the noise originating from the LEDs with a probability of 91%.

Flexible Graphite a Novel Platform for SERS Detection and Outstanding EMI Shielding

Exfoliated graphite (EG) has paying global consideration in the last decade because of the growing number of potential applications of these materials. So far, the production of EG based on binary or ternary compounds as intercalation and oxidation agents has been studied. However, the method consumes more quantity of acid, more number of compounds, time and energy. Here, we report a simple low cost one compound based rapid and efficient production of EG using microwave irradiation technique about 1min. The compressed form of EG without addition of any binder called flexible graphite sheet (FGS). As fabricated FGS shows outstanding Surface Enhanced Raman spectroscopy (SERS) detection as well as electromagnetic interference (EMI) shielding. FGS demonstrates responsive SERS for R6G molecules up to detection limit of 10-7 mol/L without any nanoparticle incorporation. The total electromagnetic interference (EMI) shielding effectiveness (SET) of – (96-84) dB was observed for FGS in the frequency region of 5-12GHz. These are the highest reported values for both (EMI shielding and detection) based on single material till today. Keywords: Exfoliated graphite, Flexible Graphite sheet, Microwave irradiation, EMI shielding and SERS.

An HF and lower VHF spectrum assessment system exploiting instantaneously wideband capture

AbstractWe report on a spectral environment evaluation and recording (SEER) system, for instantaneously wideband spectral capture and characterization in the HF and lower VHF band, utilizing a direct digital receiver coupled to a data recorder. The system is designed to contend with a wide variety of electromagnetic environments and to provide accurately calibrated spectral characterization and display from very short (ms) to synoptic scales. The system incorporates a novel RF front end involving automated gain and equalization filter selection which provides an analogue frequency‐dependent gain characteristic that mitigates the high dynamic range found across the HF and lower VHF spectrum. The system accurately calibrates its own internal noise and automatically subtracts this from low variance, external spectral estimates, further extending the dynamic range over which robust characterization is possible. Laboratory and field experiments demonstrate that the implementation of these concepts has been effective. Sensitivity to varying antenna load impedance of the internal noise reduction process has been examined. Examples of software algorithms to provide extraction and visualization of spectral behavior over narrowband, wideband, short, and synoptic scales are provided. Application in HF noise spectral density monitoring, spectral signal strength assessment, and electromagnetic interference detection is possible with examples provided. The instantaneously full bandwidth collection provides some innovative applications, and this is demonstrated by the collection of discrete lightning emissions, which form fast ionograms called “flashagrams” in power‐delay‐frequency plots.

Safety of repetitive nerve stimulation in patients with cardiac implantable electronic devices

Pacemakers and implantable cardioverter-defibrillators (ICDs) are vulnerable to inappropriate sensing of electromagnetic interference (EMI), such as from nerve conduction studies. We conducted a prospective study to assess the safety of repetitive nerve stimulation (RNS). Fourteen patients undergoing insertion of 10 ICDs and 4 pacemakers under general anesthesia received RNS of the median, axillary, and spinal accessory nerves at 2 HZ and 50 HZ. We recorded detection of EMI and whether or not this resulted in an arrhythmia diagnosis or change in pacing output. EMI was visible in 2 ICDs, without spurious tachyarrhythmia detection. EMI was observed in 3 of the 4 pacemakers, which led to pacing inhibition and a pause in 2, both of which were programmed to a unipolar sensing configuration. RNS is safe in patients with ICDs. In pacemaker patients, RNS appears safe during bipolar sensing, but caution is recommended in pacemaker patients with unipolar sensing.

Detection of Electromagnetic Interference in Microcontrollers Using the Instability of an Embedded Phase-Lock Loop

This paper presents a combined hardware-software mechanism for the detection of electromagnetic interference of a microcontroller (μC) in daily usage. This detection mechanism is based on the instability of phase-lock loop embedded in the target μC. It can detect the presence of EMI with higher sensitivity than polling the hardware status of the μC internal registers and thus provides a better detection margin within the 10 kHz to 1 GHz EMI frequency range. Despite its relative slowness and its resource consumption, it is very robust, can be implemented in virtually any application software, and does not require any electromagnetic compatibility test equipment.

Induction of Ventricular Tachycardia by Alternate Current due to an Insufficiently Grounded Electrical System

Detection of electromagnetic interference followed by inappropriate therapy by implantable cardioverter-defibrillators (ICDs) has been well documented in several case reports as well as in follow-up studies. This is a report of a case where electromagnetic interference induced ventricular tachycardia, with appropriate detection and treatment by the patient's ICD.

Separation of image-distortion sources and magnetic-field measurement in scanning electron microscope (SEM)

The electron-microscope image distortion generated by electromagnetic interference (EMI) is an important problem for accurate imaging in scanning electron microscopy (SEM). Available commercial solutions to this problem utilize sophisticated hardware for EMI detection and compensation. Their efficiency depends on the complexity of distortions influence on SEM system. Selection of a proper method for reduction of the distortions is crucial. The current investigations allowed for a separation of the distortions impact on several components of SEM system. A sum of signals from distortion sources causes wavy deformations of specimen shapes in SEM images. The separation of various reasons of the distortion is based on measurements of the periodic deformations of the images for different electron beam energies and working distances between the microscope final aperture and the specimen. Using the SEM images, a direct influence of alternating magnetic field on the electron beam was distinguished. Distortions of electric signals in the scanning block of SEM were also separated. The presented method separates the direct magnetic field influence on the electron beam below the SEM final aperture (in the chamber) from its influence above this aperture (in the electron column). It also allows for the measurement of magnetic field present inside the SEM chamber. The current investigations gave practical guidelines for selecting the most efficient solution for reduction of the distortions.

Electromagnetic Interference (EMI) and Arrhythmic Events in ICD Patients Undergoing Gastrointestinal Procedures

The objective was to determine the effect of electromagnetic interference (EMI) in patients undergoing gastrointestinal endoscopy. The implantable cardioverter-defibrillator (ICD) is the primary therapeutic modality for patients at risk for sudden cardiac death. One potential problem with ICDs is interactions with electrical devices and medical procedures causing EMI or triggering arrhythmic events. Endoscopy frequently employs electrocautery (EC) for diagnosis and treatment of gastrointestinal diseases. Current guidelines advise inactivating ICDs before any surgical procedure. There is limited information on management of ICDs during endoscopy with or without EC. We prospectively evaluated patients with ICDs undergoing endoscopic procedures at our institution. Forty-one ICD patients underwent 52 gastrointestinal endoscopies over 17 months. The mean age of the population was 66 years (51-83). There were 28 men and 13 women. Thirteen patients had single chamber devices, 25 had dual chamber devices, and 2 had biventricular ICDs. The mean tachyarrhythmia detection rate programmed was 164.7 bpm (125-188). Eighteen procedures (43.9%) required biopsy, coagulation, or polypectomy. Of these, 10 (55%) required the use of EC. Only unipolar EC with mean current 19.6 mA was used. All ICDs were programmed to detection-only with therapies off. Sensitivity was left at nominal programmed settings. Post procedure interrogation showed no detection of EMI or tachyarrhythmic events. Our study shows no EMI or arrhythmic events triggered during endoscopic procedures in patients with pectorally implanted transvenous ICDs. Routine practice of programming ICDs off for gastrointestinal procedures may not be necessary. However, larger studies are needed before change in current recommendations.