Implantable Pulse Generator Graceful Shutdown Circuit
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Solution Overview
Problem
Existing emergency shutdown circuits for implantable medical devices, such as spinal cord stimulation systems, result in data loss and incomplete shutdown processes due to abrupt power disconnection, which can lead to corrupted data and incomplete logging of critical events.
Innovation Solution
An improved emergency shutdown circuit that includes a delay element between the signal conditioning circuit and the power cut-off switch, allowing the processor to complete shutdown operations like data logging and file closure before disconnecting from the battery, ensuring a controlled and graceful shutdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If abrupt power disconnection is used for emergency shutdown, then shutdown speed is improved, but data loss and corruption occur
Solution Approach 1:
The system performs preliminary actions by detecting the emergency shutdown condition and activating a delay mechanism that provides a grace period before actual power disconnection. During this delay period, the processor completes critical shutdown operations such as saving data to non-volatile memory and closing open files, thereby preventing data loss while still achieving timely shutdown.
Solution Approach 2:
A delay element is introduced as an intermediary between the emergency shutdown trigger and the power cut-off switch. This intermediary component bridges the conflict between immediate shutdown requirements and data preservation needs by providing a controlled time window that allows safe data operations before complete power disconnection occurs.
2Loss of time
If abrupt power disconnection is used for emergency shutdown, then response time is improved, but data corruption occurs
Solution Approach 1:
The system performs preliminary data protection actions during the delay period before power disconnection. The processor is notified of the impending shutdown and executes critical operations such as flushing data buffers to non-volatile memory and closing open files, ensuring data integrity is maintained despite the time-constrained shutdown scenario.
Solution Approach 2:
The delay element provides a cushioning time window that protects against data corruption by allowing the system to complete safety operations before the harmful effect of power disconnection occurs. This beforehand cushioning ensures that even though shutdown is rapid, critical data integrity operations can complete without interruption.
3Loss of information
If delay element is added for controlled shutdown, then data protection is improved, but device complexity increases
Solution Approach 1:
A relatively simple delay element is introduced as an intermediary component between the emergency shutdown trigger and the power cut-off mechanism. This single added component provides the necessary time window for data protection operations without requiring complex control systems, thereby achieving improved data protection with minimal increase in device complexity.
Solution Approach 2:
The system changes the time parameter of the shutdown process by introducing a controllable delay period. This parameter change transforms the abrupt shutdown into a controlled shutdown with a specific time window, enabling data protection operations while keeping the overall system architecture relatively simple through straightforward temporal parameter adjustment.
4Reliability
If controlled shutdown with delay is implemented, then data integrity is improved, but shutdown duration increases
Solution Approach 1:
The delay element provides a partial shutdown duration extension that is sufficient for critical data operations but not excessively long. The system implements just enough delay to complete essential data protection tasks (saving to non-volatile memory, closing files) without unnecessarily prolonging the overall shutdown process, thereby balancing data integrity with reasonable shutdown timing.
Solution Approach 2:
Critical data protection operations are performed as preliminary actions during the delay period before complete power disconnection. By completing these essential operations in advance during the controlled shutdown window, the system ensures data integrity is achieved with minimal impact on overall shutdown duration, as the majority of the shutdown process can then proceed rapidly.
Data Source
Figure 1A~1B
Figure 2
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AI summary
An improved implantable pulse generator (IPG) containing graceful shutdown circuitry is disclosed. A magnet sensor senses the presence of an emergency shutdown magnet. Output of the magnet sensor is conditioned by a signal conditioning circuit. Output of the signal conditioning circuit is delayed by a delay element before being fed to a power cut-off switch, which cuts-off power to the IPG circuitry. An interrupt signal is routed from before the delay element to the IPG processor as an indicator of imminent shutdown. The processor launches shutdown routine that carries out shutdown operations such as logging the emergency shutdown event, saving and closing open files, saving data from volatile memory to non-volatile memory, etc., before the power cut-off switch is activated upon elapsing of delay provided by the delay element. The magnet sensor, signal conditioning circuit, and delay element are powered separately from the rest of the circuitry of the IPG.