A new approach to design safe and reliable electrical stimulator

Moradi, Saed; Maghsoudloo, Esmaeel; Lotfi, Reza

doi:10.1504/ijbet.2014.064820

Cited by 4 publications

(4 citation statements)

References 16 publications

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“…The magnitude of the push/pull current source used for the detective loop's charge balancing (I balance ) is chosen based on the application, and also as a tradeoff between the latency and the accuracy of compensation. Increasing this current's magnitude allows for quick neutralization of the accumulated charges but comes at the cost of losing neutralization precision as well as risking an unintended stimulation of neurons [16], [17], [33]. As will be described in details (Section II.D), we have chosen the I balance 's value to ensure safe and timely neutralization with sufficient accuracy demanded by the application.…”

Section: A Detective and Preventive Loops Operation Principlementioning

confidence: 99%

“…A critical point in implementing the shorting technique is controlling/limiting the discharge rate. If not limited, the discharging current could stimulate the tissue unintentionally as it has been shown that even a few µAs could depolarize a cell membrane and evoke action potentials [16], [17]. On the other hand, maintaining a very slow (but safe) discharge rate translates into a longer required time for balancing, hence imposes timing/frequency limitation on stimulation [18]- [20].…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, activating the balancing circuit at every inter-pulse resting interval significantly increases power consumption. Additionally, since the balancer should inject sub-µA-pulses (to avoid unintended stimulation [17], [33], [34]), for a large persistent imbalance, the required inter-pulse resting interval could become considerably longer, thus, limiting the maximum stimulation frequency. It should also be noted that using these high-frequency balancing pulses after every stimulation pulse could cause major side effects on neural pathways which affect the long-term effectiveness of neural stimulation [35].…”

Section: Introductionmentioning

confidence: 99%

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A 24-Channel Neurostimulator IC With Channel-Specific Energy-Efficient Hybrid Preventive-Detective Dynamic-Precision Charge Balancing

2021

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This paper presents the design, development, and experimental characterization of a 24channel programmable charge-balanced current-mode neurostimulator IC. Each channel is equipped with a quad-threshold voltage-based charge imbalance detection and a dedicated hybrid preventive-detective charge balancing circuit. The interplay of the preventive and detective control loops utilized for charge balancing has resulted in minimizing the power and timing overhead of the proposed strategy for maintaining a charge-neutral electrode-tissue interface, while avoiding the risk of unintended stimulation. The design offers dynamic programmability for the safe and unsafe charge imbalance thresholds, as well as for the balancing speed and precision. The IC is fabricated in a standard 0.18µm CMOS technology with an overall active area of 2.27mm 2 . Experimental characterization results of different circuit blocks are presented and discussed. Additionally, the IC's efficacy in conducting charge-balanced stimulation is experimentally validated under various scenarios and for the full range of stimulation current magnitude, showing the balancing accuracy, latency, and active time. Experiments are conducted both with a simplified electrical model of the interface impedance as well as in vitro. Compared to the state-of-the-art stimulators with a closed-loop charge balancer, the presented work offers the most energy-efficient charge balancing technique, the shortest required inter-pulse interval (i.e., neutralization time), and the highest balancing precision.INDEX TERMS Charge balancing, neurostimulator, implantable IC, neural interface, energy-efficient design, closed-loop control, VNS, electrical current-mode stimulation.

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Section: A Detective and Preventive Loops Operation Principlementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A 24-Channel Neurostimulator IC With Channel-Specific Energy-Efficient Hybrid Preventive-Detective Dynamic-Precision Charge Balancing

2021

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“…Pulse insertion is a method of performing charge balancing by measuring the electrode residual voltage between each stimulation phase and injecting an additional short cathodic or anodic pulse according to the polarity of the residual voltage. However, this method has the potential that the injected short pulse can induce unwanted neural reactions [24]. And the concept of offset regulation technique is similar to pulse insertion technique, but charge balancing is performed by injecting DC current instead of a short pulse.…”

Section: Introductionmentioning

confidence: 99%

An Implantable Neural Stimulator IC With Anodic Current Pulse Modulation Based Active Charge Balancing

Son

Cha

2020

IEEE Access

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Implantable electrical stimulators can be used to treat a variety of neurological disorders and restore paralyzed body functions. In electrical neural stimulation, the stimulator circuit with safe charge balancing is essential to minimize damage to electrodes and biological tissue. In this paper, an implantable current-mode neural stimulator for long-term safe electrical stimulation is presented. Anodic current pulse modulation active charge balancing technique is proposed to keep the residual voltage on the electrode within the safe window, which enables long-term safe stimulation. To ensure more complete charge balancing, the proposed active charge balancing technique can also be used with passive electrode shorting. Transistor stacking and dynamic gate biasing techniques can prevent the breakdown of standard MOSFET devices from high supply voltages, which enable the implementation of output current driver and charge balancing circuits without using HV process. The stimulator IC designed with 0.18-µm standard CMOS process can generate up to 1 mA of stimulation current and only consumes an area of 0.11 mm². Since all functions are implemented on-chip without using external components, the proposed stimulator IC is suitable for highdensity implantable stimulation applications.

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A new charge balancing scheme for electrical microstimulators based on modulated anodic stimulation pulse width

Maghsoudloo

Rezaei

Gosselin

2016

2016 IEEE International Symposium on Circuits and Systems (ISCAS)

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A new approach to design safe and reliable electrical stimulator

Cited by 4 publications

References 16 publications

A 24-Channel Neurostimulator IC With Channel-Specific Energy-Efficient Hybrid Preventive-Detective Dynamic-Precision Charge Balancing

A 24-Channel Neurostimulator IC With Channel-Specific Energy-Efficient Hybrid Preventive-Detective Dynamic-Precision Charge Balancing

An Implantable Neural Stimulator IC With Anodic Current Pulse Modulation Based Active Charge Balancing

A new charge balancing scheme for electrical microstimulators based on modulated anodic stimulation pulse width

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