scholarly journals Platform for Closed Loop Neuromodulation Based on Dual Mode Biosignals

2017 ◽  
Author(s):  
Khalid B. Mirza ◽  
Nishanth Kulasekeram ◽  
Simon Cork ◽  
Stephen Bloom ◽  
Konstantin Nikolic ◽  
...  
Keyword(s):  
Closed Loop ◽  
Compound Action Potential ◽  
Open Loop ◽  
Neural Stimulation ◽  
Appetite Control ◽  
Chemical Signatures ◽  
Signal Mode ◽  
On Chip ◽  
Final System ◽  
Compound Action

AbstractClosed loop neuromodulation, where the stimulation is controlled autonomously based on physiological events, has been more effective than open loop techniques. In the few existing closed loop implementations which have a feedback, indirect non-neurophysiological biomarkers have been typically used (e.g. heart rate, stomach distension). Although these biomarkers enable automatic initiation of neural stimulation, they do not enable intelligent control of stimulation dosage. In this paper, we present a novel closed loop neuromodulation platform based on a dual signal mode that is detecting electrical and chemical signatures of neural activity. We demonstrated it on a case of vagus nerve stimulation (VNS). Vagal chemical (pH) signal is detected and used for initiatisng VNS and vagal compound action potential (CAP) signals are used to determine the stimulation dosage and pattern. Although we used the paradigm of appetite control and neurometabolic therapies, the platform developed here can be utilised for prototyping closed loop neuromodulation systems before adapting the final System-on-Chip (SoC) design.

Release of a Neurosecretory Hormone as Peptide by Electrical Stimulation of Crab Pericardial Organs

1970 ◽  
Vol 53 (3) ◽  
pp. 679-686
Author(s):  
A. BERLIND ◽  
I. M. COOKE
Keyword(s):  
Peptide Binding ◽  
Compound Action Potential ◽  
Neural Stimulation ◽  
Distilled Water ◽  
Small Peptides ◽  
Free Peptide ◽  
Compound Action ◽  
Stimulation Of ◽  
Pericardial Organ ◽  
Bathing Fluid

1. Saline which had bathed an isolated crab pericardial organ was chromatographed on a column of Sephadex G-25. The fractions were divided and assayed for cardioexcitor activity and for ninhydrin colour following hydrolysis. 2. Fluid from pericardial organs which had been stimulated electrically to give a maximum propagated compound action potential showed both cardio-excitor activity and ninhydrin colour. These were always in the same fractions, which corresponded to the volume for elution of small peptides. Fluid from unstimulated preparations gave negative assays. 3. The cardio-excitor activity of fluid from stimulated pericardial organs and of distilled-water homogenates of pericardial organs behaved identically in Sephadex G-25 chromatography. 4. No evidence could be obtained of the cardio-excitor peptide binding to a protein. 5. This work provides evidence that neural stimulation of crab pericardial organs results in release to the bathing fluid of cardio-excitor hormone as free peptide.

Microassembly via Coordinated Manipulation of Objects Using a Multifingered Micromanipulator

2011 ◽  
Author(s):  
Christopher Pelzmann ◽  
Laxman Saggere
Keyword(s):  
Closed Loop ◽  
State Of The Art ◽  
Control Strategies ◽  
Open Loop ◽  
Open Loop Control ◽  
Multiple Objects ◽  
Loop Control ◽  
Micro Scale ◽  
Novel Approach ◽  
On Chip

This paper presents a novel approach to manipulation and assembly of micro-scale objects using a chip-scale multi-fingered micromanipulator, in which multiple, independently controlled compliant fingers coordinate with each other to grasp and manipulate multiple objects simultaneously on-chip. The structural and functional advantages of this multi-fingered micromanipulator in achieving high dexterity in a compact form as compared to other state-of-the-art manipulation tools are discussed. A formulation of the kinematics of the manipulator’s compliant fingers along with two different control strategies including an operator-driven closed-loop control and a semi-autonomous open-loop control for coordinated manipulation and on-chip assembly of micro-scale objects are introduced. Finally, the details of implementation of both control strategies and successful experimental demonstration of manipulations and assembly of two interlocking micro-scale parts with sub-micron mating clearance using the multifingered manipulator are presented.

Randomized, Double-Blind Trial of Evoked Compound Action Potential (ECAP)-Controlled Closed-Loop Spinal Cord Stimulation for Patients With Chronic Trunk and/or Limb Pain

Neurosurgery ◽  
2019 ◽  
Vol 66 (Supplement_1) ◽  
Author(s):  
Steven M Falowski
Keyword(s):  
Spinal Cord ◽  
Back Pain ◽  
Spinal Cord Stimulation ◽  
Closed Loop ◽  
Open Loop ◽  
Therapeutic Window ◽  
Double Blind ◽  
Objective Evidence ◽  
Patient Reported ◽  
Compound Action

Abstract INTRODUCTION Spinal cord stimulation (SCS) is a well-established treatment for chronic pain. Advancements in SCS systems have focused on eliminating paresthesias, but long-term success rates remain suboptimal. Variability in spinal cord (SC) activation with open-loop systems results in unpredictable inhibition of pain processing pathways, and may limit the efficacy of SCS. We report the first randomized, double-blind, pivotal study of SCS and the first therapy to measure real-time in Vivo SC neurophysiology using evoked compound action potentials (ECAPs). This study provides comparative efficacy and safety of ECAP-controlled closed-loop (CL) feedback stimulation compared to open-loop (OL) stimulation, and objective evidence of the mechanism of action of SCS. METHODS A total of 134 subjects were randomized into OL or CL. Subjects and the clinical staff were blinded to the treatment assignment. Both groups received the same device. Programming was equivalent with the only difference being that the closed-loop feedback feature was enabled in the Investigational group. A pain assessment and other patient reported outcome measures per IMMPACT were collected. ECAPs were also collected in both groups to compare the magnitude of SC activation and the percentage of time within the therapeutic window. RESULTS The primary composite endpoint demonstrated superior results in overall pain responders (P = .005) for CL-SCS (82.3%) compared to OL-SCS (60.3%). In addition, all prespecified hierarchical endpoints demonstrated better outcomes in the CL group, with both back pain reduction (P = .015) and back pain responders (P = .003) demonstrating superiority. The magnitude of SC activation was 7 times greater for CL-SCS and CL subjects spend 50% more time within the therapeutic window. In both groups, subjects showed improvements across disability, psychological, sleep, quality of life, and satisfaction. CONCLUSION ECAP-controlled closed-loop SCS has demonstrated superior overall pain relief compared to open-loop SCS. The study has just completed the primary outcome data analysis.

scholarly journals Neural stimulation systems for the control of refractory epilepsy: a review

2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Matthew D. Bigelow ◽  
Abbas Z. Kouzani
Keyword(s):  
Quality Of Life ◽  
Closed Loop ◽  
Epileptic Seizures ◽  
Open Loop ◽  
Neural Stimulation ◽  
Closed Loop Systems ◽  
Current State ◽  
Alternative Systems ◽  
Biomarker Research

Abstract Epilepsy affects nearly 1% of the world’s population. A third of epilepsy patients suffer from a kind of epilepsy that cannot be controlled by current medications. For those where surgery is not an option, neurostimulation may be the only alternative to bring relief, improve quality of life, and avoid secondary injury to these patients. Until recently, open loop neurostimulation was the only alternative for these patients. However, for those whose epilepsy is applicable, the medical approval of the responsive neural stimulation and the closed loop vagal nerve stimulation systems have been a step forward in the battle against uncontrolled epilepsy. Nonetheless, improvements can be made to the existing systems and alternative systems can be developed to further improve the quality of life of sufferers of the debilitating condition. In this paper, we first present a brief overview of epilepsy as a disease. Next, we look at the current state of biomarker research in respect to sensing and predicting epileptic seizures. Then, we present the current state of open loop neural stimulation systems. We follow this by investigating the currently approved, and some of the recent experimental, closed loop systems documented in the literature. Finally, we provide discussions on the current state of neural stimulation systems for controlling epilepsy, and directions for future studies.

scholarly journals Defining the Therapeutic Window (TW) for Spinal Cord Stimulation (SCS) Using Evoked Compound Action Potential (ECAP) Recordings: Results From the Evoke Study

Neurosurgery ◽  
2019 ◽  
Vol 66 (Supplement_1) ◽  
Author(s):  
Robert M Levy
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Stimulation ◽  
Closed Loop ◽  
Compound Action Potential ◽  
Open Loop ◽  
Therapeutic Window ◽  
Perception Threshold ◽  
Electrical Field Strength ◽  
Evoked Compound Action Potential

Abstract INTRODUCTION Spinal cord stimulation (SCS) is an established treatment for chronic pain; however, long-term success remains suboptimal. Current SCS therapies are fixed-output and do not account for large variation in electrical field strength due to changes in distance between the electrode and spinal cord (SC). METHODS In Avalon, 50 subjects were implanted and programmed in closed-loop; in Evoke, 134 subjects were randomized into open-loop (OL-SCS) or closed-loop (CL-SCS). ECAPs, a measure of SC activation, are recorded following each stimulation pulse in both groups. Each subject's therapeutic window (TW) is determined individually as the ECAP amplitude range between sensation perception threshold and discomfort. Without a measure of SC activation (eg, ECAPs), TW can only be based on perception of intensity; however, stimulation can produce variable SC activation (ECAP amplitude) as the electrode to SC distance varies with movement. RESULTS In the Evoke Study, each subjects' TW was determined in the clinic, along with the clinician prescribed level. There was no statistical difference between the 2 groups' TWs; however, CL-SCS subjects spent significantly more time in the TW despite having equivalent therapeutic ranges. Long-term data showed a similar percentage of stimuli in the TW (83%-97%). CONCLUSION TW can be individually defined by ECAP amplitudes (measure of SC activation), removing the need to rely on subjective reports of intensity, which can vary over time and with movement.

On closed-loop equilibrium strategies for mean-field stochastic linear quadratic problems

2020 ◽  
Vol 26 ◽  
pp. 41
Author(s):  
Tianxiao Wang
Keyword(s):  
Optimal Control ◽  
Closed Loop ◽  
Optimal Control Problems ◽  
Mean Field ◽  
Open Loop ◽  
Time Inconsistency ◽  
Control Problems ◽  
Linear Quadratic ◽  
Linear Quadratic Optimal Control ◽  
Equilibrium Strategies

This article is concerned with linear quadratic optimal control problems of mean-field stochastic differential equations (MF-SDE) with deterministic coefficients. To treat the time inconsistency of the optimal control problems, linear closed-loop equilibrium strategies are introduced and characterized by variational approach. Our developed methodology drops the delicate convergence procedures in Yong [Trans. Amer. Math. Soc. 369 (2017) 5467–5523]. When the MF-SDE reduces to SDE, our Riccati system coincides with the analogue in Yong [Trans. Amer. Math. Soc. 369 (2017) 5467–5523]. However, these two systems are in general different from each other due to the conditional mean-field terms in the MF-SDE. Eventually, the comparisons with pre-committed optimal strategies, open-loop equilibrium strategies are given in details.

Comparison of Dc-Dc SEPIC, CUK and Flyback Converters Based LED Drivers

2020 ◽  
pp. 99-107
Author(s):  
Erdal Sehirli
Keyword(s):  
Integrated Circuit ◽  
Closed Loop ◽  
Input Voltage ◽  
Open Loop ◽  
Current Sensor ◽  
Switching Frequency ◽  
Led Driver ◽  
Advantages And Disadvantages ◽  
Led Drivers ◽  
Conduction Mode

This paper presents the comparison of LED driver topologies that include SEPIC, CUK and FLYBACK DC-DC converters. Both topologies are designed for 8W power and operated in discontinuous conduction mode (DCM) with 88 kHz switching frequency. Furthermore, inductors of SEPIC and CUK converters are wounded as coupled. Applications are realized by using SG3524 integrated circuit for open loop and PIC16F877 microcontroller for closed loop. Besides, ACS712 current sensor used to limit maximum LED current for closed loop applications. Finally, SEPIC, CUK and FLYBACK DC-DC LED drivers are compared with respect to LED current, LED voltage, input voltage and current. Also, advantages and disadvantages of all topologies are concluded.

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