Amit J. Nimunkar

Dry electrodes for electrocardiography

Patient biopotentials are usually measured with conventional disposable Ag/AgCl electrodes. These electrodes provide excellent signal quality but are irritating for long-term use. Skin preparation is usually required prior to the application of electrodes such as shaving and cleansing with alcohol. To overcome these difficulties, researchers and caregivers seek alternative electrodes that would be acceptable in clinical and research environments. Dry electrodes that operate without gel, adhesive or even skin preparation have been studied for many decades. They are used in research applications, but they have yet to achieve acceptance for medical use. So far, a complete comparison and evaluation of dry electrodes is not well described in the literature. This work compares dry electrodes for biomedical use and physiological research, and reviews some novel systems developed for cardiac monitoring. Lastly, the paper provides suggestions to develop a dry-electrode-based system for mobile and long-term cardiac monitoring applications.

EMD-based 60-Hz noise filtering of the ECG

This study used empirical mode decomposition (EMD) for filtering power line noise in electrocardiogram signals. When the signal-to-noise (SNR) is low, the power line noise is separated out as the first intrinsic mode function (IMF), but when the SNR is high, a part of the signal along with the noise is decomposed as the first IMF. To overcome this problem, we add a pseudo noise at a frequency higher than the highest frequency of the signal to filter out just the power line noise in the first IMF. The results are compared with traditional IIR-based bandstop filtering. This technique is also implemented for filtering power line noise during enhancement of stress ECG signals.

R-peak Detection and Signal Averaging for Simulated Stress ECG using EMD

This study used empirical mode decomposition (EMD) for R-peak detection in electrocardiogram signals in the presence of electromyogram-like noise. The EMG was modeled as random white Gaussian noise with a signal-to-noise ratio (SNR) in the range of around -10 dB to -20 dB. The EMD-based R-peak detection technique gives results comparable to those obtained with the Pan-Tompkins algorithm. The EMD technique is implemented for filtering of noisy ECG signals and is further compared with a traditional low-pass filtering approach. Finally signal averaging is performed using the EMD-based R-peak detection and filtering approach and compared with the standard signal averaging technique. We conclude that the EMD based technique for R-peak detection and filtering shows promise for enhancement of the stress ECG.

Electronic medical record systems for developing countries: Review

The majority of the focus related to the modernization of medical records is placed on developed countries. However, developing countries are also progressing from paper-based records to electronic records. The requirements of their systems can be dramatically different from those of the developed world. This paper describes briefly the benefits of EMRs in developing countries. It focuses on the basic EMR information, including types of EMRs, components of EMRs, and already existing case studies, in order to establish which EMR systems would be feasible and effective for specific situations.

Safety of pulsed electric devices.

The strength-duration curve for tissue excitation can be modeled by a parallel resistor-capacitor circuit that has a time constant. We tested several short-duration electric generators: five electric fence energizers, the Taser X26 and a high-frequency generator to determine their current-versus-time waveforms. We estimated their safety characteristics using existing IEC and UL standards for electric fence energizers. The current standards are difficult to follow, with cumbersome calculations, and do not explicitly explain the physiological relevance of the calculated parameters. Hence we propose a new standard. The proposed new standard would consist of a physical RC circuit with a certain time constant. The investigator would discharge the device into a passive resistor-capacitor circuit and measure the resulting maximum voltage. If the maximum voltage does not exceed a limit, the device passes the test.

Ventricular fibrillation time constant for swine

The strength-duration curve for cardiac excitation can be modeled by a parallel resistor-capacitor circuit that has a time constant. Experiments on six pigs were performed by delivering current from the X26 Taser dart at a distance from the heart to cause ventricular fibrillation (VF). The X26 Taser is an electromuscular incapacitation device (EMD), which generates about 50 kV and delivers a pulse train of about 15-19 pulses s(-1) with a pulse duration of about 150 micros and peak current about 2 A. Similarly a continuous 60 Hz alternating current of the amplitude required to cause VF was delivered from the same distance. The average current and duration of the current pulse were estimated in both sets of experiments. The strength-duration equation was solved to yield an average time constant of 2.87 ms +/- 1.90 (SD). Results obtained may help in the development of safety standards for future electromuscular incapacitation devices (EMDs) without requiring additional animal tests.

Battery power comparison to charge medical devices in developing countries

Many people in developing countries cannot afford or rely on certain modes of electricity. We establish the reasonability of relying on lead-acid batteries, 9 V alkaline batteries, and lithium-ion batteries for charging low-voltage medical equipment. Based on the research and tests we conducted, we determined that using these battery types to charge medical devices truly is a reasonable solution.

Hands-on curriculum teaches biomedical engineering concepts to home-schooled students

University level outreach has increased over the last decade to stimulate K-12 student interest in engineering related fields. Home schooling students are one of the groups that are valued for engineering admissions due to diligent study habits and high achievement scores. However, home schooled students have inadequate access to science, math, and engineering related resources, which precludes the development of interdisciplinary teaching methods. To address this problem, we have developed a hands-on, STEM based curriculum as a safe and comprehensive supplement to current home schooling curricula. The ultimate goal is to stimulate university-student relations and subsequently increase engineering recruitment opportunities. Our pre and post workshop survey comparisons demonstrate that integrating disciplines, via the manner presented in this study, provides a K-12 student-friendly engineering learning method.

Global engineering education initiative through student organization

Engineering is becoming a more globally aware discipline that is revolutionizing the way individuals interact internationally. Engineering World Health (EWH) — Madison Chapter is a student-initiated organization that has developed opportunities to facilitate both local and global engineering education. Through EWH — Madison Chapter student-initiated activities, this organization has developed an interface between Traditional, Technical, and Translational education mediums. This study attests to the development of global engineering programs in the context of biomedical applications.

ECG synthesis based on morphing

This work presents a technique for synthesizing realistic electrocardiogram (ECG) signals by morphing two different real ECG signals. The two parent signals are interpolated using spline approximation and then over-sampled. The characteristic feature points are extracted manually from the signals and they are partitioned into component curves between the feature points. The component curves are sampled to obtain the same number of data points for each curve and the feature points are matched. One-dimensional morphing is performed to generate intermediate signals. The intermediate signals are constrained within the physiological bounds of the two real ECG signals. The realistic ECG synthesized could find application for testing an ECG-based biometric identification system and for evaluating ECG signal processing algorithms.