Overvoltage Protection Circuitry for Implantable Medical Devices
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Solution Overview
Problem
Medical devices, particularly implantable medical devices (IMDs), are vulnerable to damage from large electrical currents generated by external therapeutic or diagnostic procedures such as MRI, defibrillation, or electrocautery, which can cause damage to their internal circuitry.
Innovation Solution
Incorporating overvoltage protection circuitry within medical devices, including a capacitor to store voltage and an overvoltage protection element that shunts current if the stored voltage exceeds a threshold, thereby protecting the internal integrated circuitry from excessive voltages or currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external therapeutic or diagnostic procedures (MRI, defibrillation, electrocautery) are used to treat patients, then patient care is improved, but large electrical currents are generated that can damage the internal circuitry of implantable medical devices
Solution Approach 1:
The patent introduces an overvoltage protection circuit as an intermediary element between the external high-voltage environment and the internal sensitive circuitry. This protection circuit includes voltage detection components and current redirection paths that activate when excessive voltage is detected, effectively mediating the harmful interaction between external procedures and internal electronics without preventing the external procedures themselves.
Solution Approach 2:
The protection circuit is designed to detect voltage levels and activate protective measures before damage can occur to the internal circuitry. The circuit continuously monitors the electrical environment and prepares current alternative paths in advance, so when high voltage from external procedures is detected, the protection mechanism is already in place to redirect currents and prevent damage.
2Reliability
If the medical device includes robust overvoltage protection circuitry, then reliability during external procedures is improved, but device complexity increases
Solution Approach 1:
The protection circuit is designed to provide protection only in the specific local condition when overvoltage is detected, rather than continuously protecting all circuitry at all times. The circuit includes selective activation mechanisms that engage protective measures only in the localized situation of external procedure exposure, leaving the rest of the device simple and unchanged during normal operation.
Solution Approach 2:
The protection circuit is designed to handle multiple types of external procedures (MRI, defibrillation, electrocautery) with a single unified circuit architecture. The overvoltage detection and current redirection mechanisms work universally across different external threats, eliminating the need for separate protection circuits for each type of external procedure and thereby reducing overall complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The overvoltage protection circuitry effectively clamps the voltage across the electrodes to a safe level, preventing damage to the internal circuitry during exposure to high voltage events, ensuring the reliability and safety of the medical device.
Implementation Method 1
a capacitor configured to receive, via at least one of the current source and current sink, current generated by a first voltage across the first implantable electrode and the second implantable electrode, and store a second voltage with the received current
Implementation Method 2
an overvoltage protection element configured to shunt current from at least one of the first implantable electrode and second implantable electrode if the second voltage stored by the capacitor exceeds a threshold voltage of the overvoltage protection element
Data Source
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AI summary
Overvoltage protection circuitry configured to protect internal integrated circuits within an implantable device in the presence of a high voltage event such as defibrillation or electrocautery. The circuitry allows for an internal node to rise above the voltage level of the high voltage event to insure that an overvoltage protection element is triggered, even if the voltage level of the high voltage event is below the voltage trigger level of the overvoltage protection element.