Burst Waveform Research Articles

A Theoretical Argument for Extended Interpulse Delays in Therapeutic High-Frequency Irreversible Electroporation Treatments.

We sought to determine whether modifications to the delays within H-FIRE bursts could yield a more desirable clinical outcome in terms of ablation volume versus extent of tissue excitation. We used a modified spatially extended nonlinear node (SENN) nerve fiber model to evaluate excitation thresholds for H-FIRE bursts with varying delays. We then calculated non-thermal tissue ablation, thermal damage, and excitation in a clinically relevant numerical model. Excitation thresholds were maximized by shortening d1, and extension of d2 up to 1,000 μs increased excitation thresholds by at least 60% versus symmetric bursts. In the ablation model, long interpulse delays lowered the effective frequency of burst waveforms, modulating field redistribution and reducing heat production. Finally, we demonstrate mathematically that variable delays allow for increased voltages and larger ablations with similar extents of excitation as symmetric waveforms. Interphase and interpulse delays play a significant role in outcomes resulting from H-FIRE treatment. Waveforms with short interphase delays (d1) and extended interpulse delays (d2) may improve therapeutic efficacy of H-FIRE as it emerges as a clinical tissue ablation modality.

Mismatched Filters for Incoherent Pulse Compression in Laser Radar

A pulsed laser system is considered for long-range target detection. Single-pulse power received from a target may be low compared to the noise and background clutter power. Due to long-range and short laser wavelength, multi-pulse coherent processing is not possible, so incoherent detection is employed. Incoherent pulse compression sums received power from numerous pulses to increase SNR while maintaining single pulse range resolution. Following Levanon, aperiodic burst waveforms of on-off Keying (OOK) modulated transmitted pulses are derived from binary codes with optimal auto-correlation minimum integrated sidelobe level and minimum peak sidelobe level codes. Pulse compression uses real, continuous mismatched filters of lengths equal to or greater than the OOK code length. Filter values minimize a weighted sum of ISL and filter output power, the latter to increase SNR gain relative to that of a single pulse. Weighting can be adjusted to lower ISL for multiple target discrimination or to increase SNR gain for dim targets. A simple evolutionary modulation of the initial OOK code exchanges pairs of dissimilar samples to keep the number of on samples from decreasing and improves ISL performance. A very fast filter calculation is employed that permits an exploration of a wide variation in parameters.

Efficient photocapacitors via ternary hybrid photovoltaic optimization for photostimulation of neurons.

Optoelectronic photoelectrodes based on capacitive charge-transfer offer an attractive route to develop safe and effective neuromodulators. Here, we demonstrate efficient optoelectronic photoelectrodes that are based on the incorporation of quantum dots (QDs) into poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-Phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunction. We control the performance of the photoelectrode by the blend ratio, thickness, and nanomorphology of the ternary bulk heterojunction. The optimization led to a photocapacitor that has a photovoltage of 450 mV under a light intensity level of 20 mW.cm-2 and a responsivity of 99 mA/W corresponding to the most light-sensitive organic photoelectrode reported to date. The photocapacitor can facilitate action potential generation by hippocampal neurons via burst waveforms at an intensity level of 20 mW.cm-2. Therefore, the results point to an alternative direction in the engineering of safe and ultra-light-sensitive neural interfaces.

Recognizing Non-Collaborative Radio Station Communication Behaviors Using an Ameliorated LeNet.

This work improves a LeNet model algorithm based on a signal’s bispectral features to recognize the communication behaviors of a non-collaborative short-wave radio station. At first, the mapping relationships between the burst waveforms and the communication behaviors of a radio station are analyzed. Then, bispectral features of simulated behavior signals are obtained as the input of the network. With regard to the recognition neural network, the structure of LeNet and the size of the convolutional kernel in LeNet are optimized. Finally, the five types of communication behavior are recognized by using the improved bispectral estimation matrix of signals and the ameliorated LeNet. The experimental results show that when the signal-to-noise ratio (SNR) values are 8, 10, or 15 dB, the recognition accuracy values of the improved algorithm reach 81.5%, 94.5%, and 99.3%, respectively. Compared with other algorithms, the training time cost and recognition accuracy of the proposed algorithm are lower and higher, respectively; thus, the proposed algorithm is of great practical value.

Cervical Spinal Cord Stimulation Using Monophasic Burst Waveform for Axial Neck and Upper Extremity Radicular Pain: A Preliminary Observational Study

Cervical spinal cord stimulation (cSCS) is an accepted therapeutic option for radicular upper extremity pain and less commonly for cervical axial pain despite less available literature in comparison with lumbar and lower extremity applications. This preliminary observational pilot study evaluated the efficacy of cSCS using the monophasic burst pattern in the treatment of both upper extremity radicular pain and axial neck pain. Primary outcome measures were reduction in pain scores, global pain scale (GPS) indices, and neck Oswestry disability index (nODI). Of the 23 subjects trialed, 15 went to implantation of cSCS using burst and were followed for 1 year prospectively. Pre- and postprimary outcome measures suggested a statistically (p < 0.05) and clinically significant 12.40 point differential in the nODI, a statistically significant reduction of the GPS from 74.60 to 56.37 (p < 0.05), and a reduction in the pain rating score from 8.13 +/- 1.0 prior to trial to 3.85 +/- 1.1 at 1 year for axial neck and with and without radicular pain (p < 0.05). This preliminary study suggests that the use of the burst waveform applied to cSCS results in improved function and decreased pain scores in subjects with axial neck pain with and without radicular symptomatology and cervicogenic headache.

Harmonic-balance circuit analysis for electro-neural interfaces

Objective. Avoidance of the adverse electrochemical reactions at the electrode-electrolyte interface defines the voltage safety window and limits the charge injection capacity (CIC) of an electrode material. For an electrode that is not ideally capacitive, the CIC depends on the waveform of the stimulus. We study the modeling of the charge injection dynamics to optimize the waveforms for efficient neural stimulation within the electrochemical safety limits. Approach. The charge injection dynamics at the electrode-electrolyte interface is typically characterized by the electrochemical impedance spectrum, and is often approximated by discrete-element circuit models. We compare the modeling of the complete circuit, including a non-linear driver such as a photodiode, based on the harmonic-balance (HB) analysis with the analysis based on various - (discrete-element) approximations. To validate the modeling results, we performed experiments with iridium-oxide electrodes driven by a current source with diodes in parallel, which mimics a photovoltaic circuit. Main results. Application of HB analysis based on a full impedance spectrum eliminates the complication of finding the discrete-element circuit model in traditional approaches. HB-based results agree with the experimental data better than the discrete-element circuit. HB technique can be applied not only to demonstrate the circuit response to periodic stimulation, but also to describe the initial transient behavior when a burst waveform is applied. Significance. HB-based circuit analysis accurately describes the dynamics of electrode-electrolyte interfaces and driving circuits for all pulsing schemes. This allows optimizing the stimulus waveform to maximize the CIC, based on the impedance spectrum alone.

Acoustic Emission Burst Extraction for Multi-Level Leakage Detection in a Pipeline

Acoustic emission bursts are signal waveforms that include a number of consecutive imbrication transients with variable strengths and contain crucial information on the leakage phenomenon in a pipeline system. Detection and isolation of a burst against the background signal increases the ability of a pipe’s fault diagnosis system. This paper proposes a methodology using the Enhanced Constant Fault Alarm Rate (ECFAR) to detect bursts and exploit the burst phenomenon in acoustic emission. The extracted information from the burst waveform is used to distinguish several levels of leakage in a laboratory leak-off experimental testbed. The multi-class support vector machine in the one-against-all method is established as the classifier. The results are compared with those of the wavelet threshold-based method, another algorithm utilized for impulse and burst detection, which indicates that the ECFAR method gives an ameliorative classification result with an accuracy of 93% for different levels of leakage.

Investigation of Galling Wear Using Acoustic Emission Frequency Characteristics

In the sheet metal stamping process, during sliding contact between the tool and sheet, it is expected that severe events such as tool wear or fracture on the sheet generate acoustic emission (AE) burst waveforms. Attempts have been made in the literature to correlate the AE burst waveform with the wear mechanisms. However, there is a need for additional studies to understand the frequency characteristics of the AE burst waveform due to the severity and progression of the galling wear. This paper will determine the AE frequency characteristics that can be used to monitor galling wear, independent of the experimental process examined. The AE burst waveforms generated during the stamping and scratch tests are analysed in this paper to understand the change in the AE frequency characteristics with the galling severity. These AE burst waveforms were investigated using the Hilbert Huang Transform (HHT) time-frequency technique, band power, and mean-frequency. Subsequently, these AE frequency features are correlated with the wear behaviour observed via high-resolution profilometer images of the stamped parts and scratch surfaces. Initially, the HHT technique is applied to the AE burst waveform to understand the influence of wear severity in the power distribution over the wide AE frequency range. Later, the AE bandpower feature is used to quantitatively analyse the power in each frequency interval during the unworn and worn tool conditions. Finally, the mean-frequency of AE signal is identified to be able to determine the onset of galling wear. The new knowledge defined in this paper is the AE frequency features and wear measurement feature that can be used to indicate the onset of galling wear, irrespective of the processes examined.

Evolutionary multi‐objective optimisation of the pulse burst waveform in solid‐state VHF moving target detection radar

A solid-state, very high frequency (VHF) band, moving target detection air surveillance radar requires a complex pulse burst waveform to mitigate the visibility issues originating from the blind Doppler intervals and range eclipsing. The waveform employs multiple pulse repetition frequencies to mitigate the effects of the blind Doppler intervals and interleaves short and long pulses to mitigate range eclipsing. In the authors’ previous works, they pointed out that the waveform design is a multi-objective optimisation problem and defined the mathematical model of the waveform optimisation problem. They also presented how the exact Pareto optimal (PO) set can be determined by means of exhaustive search. In this paper, they improve the mathematical model of the waveform optimisation problem by altering the way in which one of the objective functions is calculated and adding a new constraint, which eliminates meaningless solutions. Finally, they propose a solution method based on a multi-objective evolutionary algorithm. The performance evaluation test indicates that compared to the exhaustive search, the proposed method provides a solution that is insignificantly different. However, the proposed method is more scalable and requires over three orders of magnitude smaller number of comparisons to determine the PO set, which makes it more viable for the online waveform adaptation.

Clarifying the Scientific Knowledge Pertaining to Burst Waveforms in Spinal Cord Stimulation

Clarifying the Scientific Knowledge Pertaining to Burst Waveforms in Spinal Cord Stimulation

Costas Array Waveforms for Closely Spaced Target Detection

In this paper, we consider requirement-driven selection of Costas arrays for the detection of closely spaced targets. We review existing order selection strategies in terms of the time–bandwidth product and treat selection of specific Costas arrays separably. Our computational analyses prioritize a clear central region in single-pulse discrete ambiguity functions (DAFs) and also address maximum frequency hops. Using finite field arithmetic, we significantly generalize results about 1s in the central square DAF regions for Welch and Lempel–Golomb arrays, and prove two general results about the nonexistence of such clear regions. We find that order 14 is very beneficial for target detection in which Costas arrays having an almost entirely clear $5 \times 5$ square central region in the single-pulse DAF exist and feature the corresponding time–bandwidth product of 196 within an example. We feature a first-principles system simulation with such an order-14 Costas array to obtain a 3-dB target detection improvement. Since radars commonly use burst waveforms, we also consider three different kinds of bursts and discuss their merits using ambiguity function analyses. We provide supporting computational database surveys on central rectangular $3 \times m$ regions.

Mechanism of Action in Burst Spinal Cord Stimulation: Review and Recent Advances.

ObjectiveThis is a comprehensive, structured review synthesizing and summarizing the current experimental data and knowledge about the mechanisms of action (MOA) underlying spinal cord stimulation with the burst waveform (as defined by De Ridder) in chronic pain treatment.MethodsMultiple database queries and article back-searches were conducted to identify the relevant literature and experimental findings for results integration and interpretation. Data from recent peer-reviewed conference presentations were also included for completeness and to ensure that the most up-to-date scientific information was incorporated. Both human and animal data were targeted in the search to provide a translational approach in understanding the clinical relevance of the basic science findings.Results/ConclusionsBurst spinal cord stimulation likely provides pain relief via multiple mechanisms at the level of both the spinal cord and the brain. The specific waveforms and temporal patterns of stimulation both play a role in the responses observed. Differential modulation of neurons in the dorsal horn and dorsal column nuclei are the spinal underpinnings of paresthesia-free analgesia. The burst stimulation pattern also produces different patterns of activation within the brain when compared with tonic stimulation. The latter may have implications for not only the somatic components of chronic pain but also the lateral and affective pathway dimensions as well.

Effectiveness of tonic and burst motor cortex stimulation in chronic neuropathic pain.

Background: Motor cortex stimulation (MCS) is an intracranial, invasive method for treatment of chronic pain. Main indications for MCS are central post stroke pain, neuropathic facial pain, phantom limb pain and brachial plexus or spinal cord injury pain. Spinal cord stimulation (SCS) with burst waveform has been proved to be more effective than tonic mode in chronic pain. Necessity to replace depleted batteries of motor cortex tonic stimulators gave us an opportunity of applying burst stimulation. The objective of the pilot study was to evaluate the effects of burst stimulation applied on motor cortex in patients with chronic pain syndromes as well as comparison to tonic mode.Materials and methods: We have evaluated 6 patients (females N=3, males N=3) belonging to the group of 14 cases (females N=5, males N=9) who had undergone surgical procedure of MCS in years 2005–2017. Selected for the study were 6 patients with thalamic pain N=3, with facial pain N=3 (anaesthesia dolorosa and neuropathic trigeminal neuralgia). The patients were subjected to both modes of stimulation then they chose which one was better in relieving pain: tonic or burst. Pain intensity was assessed with the visual analogue scale (VAS) before the replacement of implanted pulse generator (IPG) and after the stimulation with tonic and burst modes.Results: In the study, 5 out of 6 patients with MCS found burst mode more effective than tonic mode. Baseline VAS score in patients that had at least 3 months depleted battery of tonic IPG was 95 mm. After implantation of a new IPG mean VAS score on tonic stimulation was 72 mm, on burst 53 mm.Conclusions: The most preferred option of MCS in selected group of patients was burst stimulation. This study has shown, that the burst stimulation of cerebral cortex is a promising modality when tonic stimulation is not sufficient in refractory, neuropathic pain.

Burst SCS Microdosing Is as Efficacious as Standard Burst SCS in Treating Chronic Back and Leg Pain: Results From a Randomized Controlled Trial

The burst waveform, a recent innovation in spinal cord stimulation (SCS), can achieve better outcomes than conventional tonic SCS, both for de novo implants and as a salvage therapy. Burst stimulation delivers more energy per second than tonic stimulation, which is a consideration for battery consumption. The clinical effectiveness of an energy-conserving strategy was investigated. Subjects were experienced users of BurstDR SCS for back and leg pain. Three 2-week stimulation paradigms were presented in blinded random order: standard (continuously delivered) BurstDR, microdosing A: 5 sec of BurstDR alternating with 5 sec of no stimulation, and microdosing B: 5 sec of BurstDR alternating with 10 sec of no stimulation. The primary outcome for each paradigm was change in pain ratings, and secondary outcomes included changes in scores for quality of life, satisfaction, and preference. Twenty-five subjects assessed all three stimulation paradigms. There were no significant differences in pain (visual analog scale) or quality of life (EQ-5D) when comparing standard burst outcomes with those of microdosing A and, separately, microdosing B. Microdosing paradigms were graded with slightly higher level of satisfaction and were generally preferred above standard burst stimulation. These results suggest that the use of energy-efficient burst microdosing stimulation paradigms with alternating stimulation-on and stimulation-off periods can provide clinically equivalent results to standard burst stimulation. This is important for extending SCS battery life. Further research is needed to comprehensively characterize the clinical utility of this approach and the neurophysiological mechanisms for the maintenance of pain relief during stimulation-off periods.

Abstract #27: Modeling the Physiological Effects of Burst Stimulation: Influence of Active vs. Passive Recharge Phases

Introduction: Burst stimulation patterns consist of packets of relatively high frequency stimulation pulses repeated over time at lower frequencies and have produced promising outcomes when used with spinal cord stimulation (SCS) to treat neuropathic pain. A recent hypothesis proposes that the passive or active nature of the burst waveform recharge phase may influence outcomes due to the “postsynaptic non-linear buildup of the super-action potential” by passive recharge burst (De Ridder, commentary in Neuromodulation, 2017), but this hypothesis has not been proven. The aim of this study is to use computational modeling to discern differences between physiological effects in the activation of dorsal columns (DC), such as axon activation threshold and action potential (AP) shape, produced by active vs. passive recharge burst stimulation to gain mechanistic insights that may drive waveform optimization.

In-situ monitoring of stress corrosion cracking of 304 stainless steel in high-temperature water by analyzing acoustic emission waveform

Stress corrosion cracking (SCC) of 304 stainless steel (SS) in high-temperature water was in-situ monitored by analyzing acoustic emission (AE) waveform. Several SCC modes including transgranular SCC (TGSCC), intergranular SCC (IGSCC) and mixture of TGSCC and IGSCC were obtained by changing material state and controlling load mode, dissolved oxygen concentration. Typical burst and continuous waveform of the AE signals were detected. The AE sources and the relationship between AE waveform and SCC process are discussed. A procedure for applying AE to in-situ monitor SCC is proposed.

Development of ball surface acoustic wave trace moisture analyzer using burst waveform undersampling circuit.

The measurement and control of trace moisture, where the water concentration is lower than 1 ppmv [-76.2 °C for the frost point (°CFP)], are essential for improving the yield rate of semiconductor devices and for ensuring their reliability. A ball surface acoustic wave (SAW) sensor with a sol-gel silica coating exhibited useful characteristics for a trace moisture analyzer (TMA) when the temperature drift of the delay time output was precisely compensated using two-frequency measurement (TFM), where the temperature-compensated relative delay time change (RDTC) was obtained by subtracting the RDTC at the fundamental frequency from that at the third harmonic frequency on an identical propagation path. However, the cost of the measurement circuit was a problem. In this study, a burst waveform undersampling (BUS) circuit based on the theory of undersampling measurement was developed as a practical means. The BUS circuit was useful for precise temperature compensation of the RDTC, and the ball SAW TMA was prototyped by calibrating the RDTC using a TMA based on cavity ring-down spectroscopy (CRDS), which is the most reliable method for trace moisture measurement. The ball SAW TMA outputted a similar concentration to that obtained by the CRDS TMA, and its response time at a set concentration in N2 with a flow rate of 1 l/min was about half that of the CRDS TMA, suggesting that moisture of -80 °CFP was measured within only 1 min. The detection limit at a signal-to-noise ratio of 3 was estimated to be 0.05 ppbv, comparable with that of the CRDS TMA. From these results, it was demonstrated that a practical ball SAW TMA can be realized using the developed BUS circuit.

Success Using Neuromodulation With BURST (SUNBURST) Study: Results From a Prospective, Randomized Controlled Trial Using a Novel Burst Waveform.

El objetivo del estudio multicéntrico, aleatorizado, no ciego y cruzado fue determinar la seguridad y eficacia de un dispositivo que administra estimulación tónica tradicional y estimulación en ráfagas a pacientes con dolor crónico axial y/o extremidades. Luego de una prueba con estimulación tónica exitosa, 100 individuos fueron aleatorizados para recibir un modo de estimulación durante las primeras 12 semanas, y luego el otro modo de estimulación durante las siguientes 12 semanas. Este estudio piloto presentó a 12 pacientes que se sometieron a un período de prueba de un mes con un generador de pulso externo. Durante el período de prueba, la estimulación en ráfagas dio como resultado una reducción del 84% y del 96% desde el inicio en las puntuaciones de la escala visual analógica (EVA) medias para el dolor axial y de extremidades, respectivamente.

Roles of Na+, Ca2+, and K+ channels in the generation of repetitive firing and rhythmic bursting in adrenal chromaffin cells.

Adrenal chromaffin cells (CCs) are the main source of circulating catecholamines (CAs) that regulate the body response to stress. Release of CAs is controlled neurogenically by the activity of preganglionic sympathetic neurons through trains of action potentials (APs). APs in CCs are generated by robust depolarization following the activation of nicotinic and muscarinic receptors that are highly expressed in CCs. Bovine, rat, mouse, and human CCs also express a composite array of Na+, K+, and Ca2+ channels that regulate the resting potential, shape the APs, and set the frequency of AP trains. AP trains of increasing frequency induce enhanced release of CAs. If the primary role of CCs is simply to relay preganglionic nerve commands to CA secretion, why should they express such a diverse set of ion channels? An answer to this comes from recent observations that, like in neurons, CCs undergo complex firing patterns of APs suggesting the existence of an intrinsic CC excitability (non-neurogenically controlled). Recent work has shown that CCs undergo occasional or persistent burst firing elicited by altered physiological conditions or deletion of pore-regulating auxiliary subunits. In this review, we aim to give a rationale to the role of the many ion channel types regulating CC excitability. We will first describe their functional properties and then analyze how they contribute to pacemaking, AP shape, and burst waveforms. We will also furnish clear indications on missing ion conductances that may be involved in pacemaking and highlight the contribution of the crucial channels involved in burst firing.

Moisture adsorption desorption characteristics of stainless steel tubing measured by ball surface acoustic wave trace moisture analyzer

A ball surface acoustic wave (SAW) trace moisture analyzer (TMA) was applied to measuring the adsorption and desorption (AD) characteristics of a stainless steel tube. For the first time, two-frequency measurement for precise temperature compensation was attempted at intervals of 3 s using a burst waveform undersampling circuit. We succeeded in measuring the variations of moisture transit time and dry-down dynamics caused by inner surface treatments such as bright annealing (BA), electropolishing (EP), and electrochemical buffing (ECB) using a sample-tube length of only 100 mm at a flow rate of 0.1 L/min. Net moisture adsorption was evaluated from the measured adsorption subtracted by the background adsorption. As a result, it was found that the adsorption on the ECB tube was smaller than those on EP and BA tubes by 1/3 and 1/4, respectively, at a baseline concentration of 13 ppbv. From these results, it was demonstrated that the ball SAW TMA could be used for measuring the AD characteristics of stainless steel tubes with various surface treatments.