Unidirectional Current Sources for Neurostimulator Chip Area Reduction

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Solution Overview

Problem

Existing neurostimulator devices lack the capability to individually control the amount of electrical stimulation delivered by each electrode and require a large number of transistors for neurostimulation circuitry, leading to increased fabrication costs and chip area consumption.

Innovation Solution

The neurostimulator device incorporates a microcontroller with firmware and control logic that uses a plurality of transistors to create individually controllable electrical paths, allowing for variable electrical stimulation delivery through programmable switches and current sinks, reducing the need for bidirectional current supplies and minimizing chip area consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If bidirectional current supplies are used to control each electrode, then individual electrode control capability is improved, but device complexity and transistor count increase

Engineering Contradiction:

Improveindividual electrode control capabilityVSAvoidtransistor count

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the current control function by using separate unidirectional current sources for anodes and cathodes, with independent switches controlling current flow to each electrode. This allows individual electrode control while simplifying the overall current supply architecture compared to bidirectional sources.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of using bidirectional current sources that can source or sink current, the patent inverts the approach by using unidirectional current sources combined with switches. The switches control the direction of current flow by selectively connecting electrodes to appropriate current sources, thereby achieving bidirectional control capability through unidirectional components.

Inventive Principle:

Principle #13The other way round (Inversion)

2Adaptability or versatility

If bidirectional current supplies are used for each electrode, then individual stimulation control is improved, but chip area consumption increases

Engineering Contradiction:

Improveindividual stimulation controlVSAvoidchip area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent merges multiple bidirectional current source functions into separate unidirectional current sources that are shared among multiple electrodes. By combining the current sourcing function into centralized unidirectional sources and using switches for individual electrode control, the overall chip area is reduced compared to having dedicated bidirectional sources for each electrode.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The unidirectional current sources serve multiple electrodes simultaneously, making them universal components. Each current source can supply current to multiple electrodes through switch selection, reducing the total number of current source circuits needed and thereby reducing chip area consumption.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Area of stationary object

If unidirectional current sources with switches are used, then chip area is reduced, but current control flexibility may be limited

Engineering Contradiction:

Improvechip areaVSAvoidcurrent control flexibility

Core Design Contradiction:

Area of stationary objectVSAdaptability or versatility

Solution Approach 1:

The patent introduces dynamic control through switches that can be programmably activated or deactivated based on stimulation requirements. This dynamic switching capability allows the system to adapt current flow paths in real-time, maintaining current control flexibility despite using simplified unidirectional current sources.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The switches act as intermediaries between the unidirectional current sources and the electrodes. These intermediary components enable flexible current distribution by selectively connecting current sources to different electrodes, thereby compensating for the limited directionality of unidirectional sources and maintaining overall control flexibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP3053627B1Current steering neurostimulator device with unidirectional current sources

Publication Date: 2020.01.01 NUVECTRA CORP

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AI summary

The present disclosure provides a medical device that includes a neurostimulator. The neurostimulator includes one or more channels. Each channel includes a digitally-controlled switch coupled to a voltage source. The switch is in one of an "on" state and an "off" state in response to a first control signal. Each channel also includes a digitally-controlled current sink coupled to the switch. The current sink is coupled between the switch and the voltage source. The current sink draws a variable amount of electrical current in response to a second control signal. Each channel further includes a conductor coupled to the switch and the current sink. The conductor is configured to be coupled to an electrode that is operable to deliver the electrical current drawn by the current sink to a target tissue area.