Surgical Stapler Motor Control via Temperature Feedback
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Solution Overview
Problem
Current surgical stapling systems face challenges in efficiently powering and controlling the operation of surgical instruments, particularly in ensuring safe and reliable energy delivery and preventing accidental activation when the interchangeable shaft assembly is not coupled to the handle.
Innovation Solution
The surgical system incorporates a segmented power circuit with a safety processor and primary processor to manage energy distribution, includes a usage cycle counter to track instrument usage, and employs a magnetic field sensor to detect the presence of the shaft assembly, ensuring safe operation and preventing unintended activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the surgical stapler uses an electric motor with high current draw, then the motor can deliver sufficient power for stapling and cutting operations, but the motor generates excessive heat that can damage surrounding tissue
Solution Approach 1:
The motor controller implements periodic duty cycling where the motor operates at full power only during brief stapling/cutting cycles, then rests to cool down. This periodic operation pattern allows the motor to deliver high power when needed while limiting cumulative heat generation that could damage tissue.
Solution Approach 2:
The system dynamically adjusts motor operating parameters including current draw, pulse width modulation duty cycle, and rotation speed based on real-time temperature feedback from the temperature sensor. This parameter adaptation allows the motor to maintain sufficient power for surgical functions while operating below thermal damage thresholds.
2Productivity
If the motor controller allows continuous high-power operation, then surgical tasks can be performed quickly and efficiently, but the instrument risks overheating and causing tissue damage
Solution Approach 1:
The temperature sensor continuously monitors motor temperature and feeds this information back to the motor controller. The controller uses this feedback to automatically adjust power delivery, reducing or interrupting power when temperature approaches dangerous thresholds, thereby preventing tissue damage while maintaining surgical productivity.
Solution Approach 2:
The motor controller dynamically adapts its power delivery strategy based on real-time temperature conditions and surgical task requirements. The system transitions between high-power modes for active stapling/cutting and low-power or zero-power modes for cooling periods, optimizing both surgical efficiency and thermal safety.
3Ease of operation
If the surgical stapler uses a battery-powered electric motor, then the instrument achieves portability and flexibility for minimally invasive surgery, but the battery must be recharged or replaced frequently during use
Solution Approach 1:
The system performs preliminary monitoring of battery charge levels and provides advance warning to the surgeon. The instrument can be disconnected from the battery pack before complete depletion, allowing the surgeon to replace or recharge the battery proactively rather than reactively, minimizing interruption to surgical procedures.
Solution Approach 2:
The battery management system automatically monitors charge status, manages power consumption, and coordinates battery replacement without requiring manual intervention from the surgeon. The system optimizes power usage to extend battery life and ensures continuous operation through automated battery management.
4Ease of operation
If the battery pack remains connected to the handle when not in use, then the instrument is ready for immediate operation, but accidental activation or energy waste may occur
Solution Approach 1:
The system performs preliminary detection of shaft assembly presence using magnetic field sensors before enabling motor operation. When no shaft is detected, the motor controller remains in a low-power standby state, preventing accidental activation while maintaining readiness for immediate operation when the shaft is attached.
Solution Approach 2:
The system replaces mechanical switches or physical connections with magnetic field-based detection and electronic control. This substitution allows for non-contact sensing of shaft presence and electronic control of power delivery, eliminating the need for physical on/off switches and enabling more precise control over when the motor can operate.
5Productivity
If the motor controller enables motor operation without shaft assembly detection, then the instrument can be activated immediately, but unintended activation may cause safety hazards
Solution Approach 1:
The motor controller performs preliminary detection of the shaft assembly's magnetic signature before allowing motor activation. This pre-check ensures that the shaft is properly attached and positioned, preventing unintended activation while maintaining rapid response time once the shaft is in place.
Solution Approach 2:
The magnetic field sensor acts as an intermediary between the battery pack and the motor controller. It detects the presence of the shaft assembly and communicates this information to the controller, which uses it as a safety condition for enabling motor operation. This intermediary layer provides safety verification without significantly delaying activation.
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 system ensures safe and reliable energy delivery to surgical instruments, prevents accidental activation, and tracks usage to prevent overuse, enhancing operational safety and efficiency.
Implementation Method 1
a magnetic field sensor to detect the presence of the shaft assembly
Implementation Method 2
an electric motor mechanically coupled to the drive system
Implementation Method 3
a battery electrically coupled to the electric motor
Data Source
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AI summary
A surgical stapler. The surgical stapler includes a drive system, an electric motor, a battery and a control system. The electric motor is mechanically coupled to the drive system. The battery is electrically couplable to the electric motor. The control system is electrically connected to the electric motor and includes an H-bridge circuit and a temperature sensing device. The H-bridge circuit includes a high side and a low side. The low side of the H-bridge circuit includes first and second switching devices, and a resistive heating element electrically connected in series with the first switching device. The temperature sensing device is positioned proximate the resistive heating element. The control system is configured to control a force applied to the drive system based on a temperature associated with the resistive heating element and sensed by the temperature sensing device.