Power Control Circuit for Sealed Ethylene Oxide Sterilization
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Solution Overview
Problem
Electronic medical devices, such as trial stimulators for implantable neurological stimulation systems, face the challenge of safely being sterilized in flammable environments like those containing ethylene oxide gas without the risk of ignition due to residual electrical energy.
Innovation Solution
A power control circuit using a bi-stable switch, such as a JK flip-flop, to manage the energy storage in the device, ensuring it is below the ignition level of the sterilizing gas, and a remotely actuatable switch to awaken the device safely from the sealed packaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the device is sterilized in a flammable environment (ethylene oxide gas), then sterilization is achieved, but the risk of ignition due to residual electrical energy increases
Solution Approach 1:
The device performs preliminary actions before sterilization by discharging all energy storage elements (capacitors, batteries) to below ignition levels of flammable sterilizing gases. The power control circuit is configured to automatically discharge energy storage elements before the device is placed in the sterilization environment, eliminating the ignition risk while maintaining sterilization effectiveness.
Solution Approach 2:
The patent changes the energy parameter of the device by controlling the power control circuit to reduce stored energy in capacitors and other energy storage elements to levels below the ignition threshold of flammable sterilizing gases. This parameter change allows the device to safely withstand sterilization in flammable environments without risk of explosion.
2Reliability
If the device is sealed in packaging for sterilization, then sterility is maintained, but the ability to test or activate the device before use is limited
Solution Approach 1:
The patent segments the device functionality into two distinct modes: a first state before sterilization where the device can be tested and programmed, and a second state during/after sterilization where the device is in a low-power or disabled state to prevent ignition. The power control circuit enables this segmentation by controlling power distribution to different circuit components based on the sterilization status.
Solution Approach 2:
The power control circuit dynamically adjusts the operational state of the device based on environmental conditions. Before sterilization, the device operates normally for testing and programming. During sterilization, the circuit automatically transitions to a low-energy state. After sterilization, the device can be reactivated, providing dynamic adaptability throughout the sterilization process.
3Object-affected harmful factors
If energy storage elements are discharged to below ignition levels, then safety in flammable environments is ensured, but device functionality may be compromised
Solution Approach 1:
The patent implements periodic action by cycling the device through different operational states. Before sterilization, the device is fully functional for testing. During sterilization, energy storage elements are discharged to safe levels. After sterilization, the device can be recharged and reactivated, maintaining functionality while ensuring safety during the critical sterilization period.
Solution Approach 2:
The power control circuit acts as an intermediary between the energy storage elements and the rest of the device circuitry. It controls the discharge and recharge cycles, mediating between the safety requirement (discharged state during sterilization) and the functionality requirement (charged state during operation). This intermediary control ensures both safety and functionality are maintained at appropriate times.
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
Ensures the device is safe to be exposed to flammable sterilizing gases by reducing stored energy to non-ignitable levels and allowing remote activation without breaking the sterile seal, thus preventing explosions and maintaining functionality.
Implementation Method 1
A power control circuit can be used with a trial stimulator to reduce the amount of energy stored in the trial stimulator to a level that allows the trial stimulator to be safely exposed to (e.g., placed in) a flammable sterilizing gas
Implementation Method 2
In the sleep state, the power control circuit places the connected circuitry in a sleep state and minimizes the amount of energy stored in the circuitry
Implementation Method 3
The remotely actuatable switch can be actuated through the packaging so that the trial stimulator need not be removed from the packaging in order to cause the power control circuit to produce an output that puts the connected circuitry in the run state
Data Source
AI summary
A power control circuit for use with devices that will be placed in a flammable sterilizing gas includes a bi-stable switch that is configured to produce an output to place the circuitry of a connected device in a run state or a sleep state. The bi-stable switch controls one or more transistors to drain energy from energy storage devices in the circuitry of the connected device to a level below an ignition level of a sterilizing gas. A remotely actuatable switch can be actuated from outside of a packaging in which the power control circuit is placed to cause the bi-stable switch to produce an output that puts the circuitry in the run state without removing the power control circuit from the packaging.