Gas-Inflatable Balloon Contact Force Sensor for Minimally Invasive Surgery
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Solution Overview
Problem
Current robotic surgical and diagnostic instruments lack the ability to measure contact force effectively within a patient's body, as conventional force sensors are too bulky for minimally invasive procedures, not sterilizable, and do not provide tactile feedback, posing risks and inefficiencies in procedures like tumor assessment and tissue handling.
Innovation Solution
A contact force sensor device integrated with a gas-inflatable balloon that can be inflated and deflated to measure contact forces with tissues, using a processing unit to calculate and notify the operator of contact forces, allowing for precise force measurement and minimal tissue stress, while being compact and sterilizable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional force sensors are used, then contact force measurement capability is provided, but the sensor size becomes too bulky for minimally invasive procedures
Solution Approach 1:
The force sensor is segmented into multiple independent strain gauge elements arranged on the balloon surface. Each strain gauge measures local deformation, and the combined output provides comprehensive force measurement data while keeping each individual sensor element extremely small and suitable for minimally invasive applications.
Solution Approach 2:
The invention uses a gas-inflatable balloon as the sensing element. The balloon is inflated with gas to a controlled pressure, and when it contacts tissue, the internal gas pressure changes in response to the contact force. This pneumatic mechanism allows force measurement without requiring bulky mechanical sensor components, achieving both small size and measurement capability.
2Measurement precision
If conventional force sensors with electronic parts are used, then contact force measurement is enabled, but the sensor cannot tolerate severe sterilization conditions
Solution Approach 1:
The force sensor is designed as a disposable device that can be sterilized using conventional medical sterilization methods. The sensor components, particularly the strain gauges and balloon, are constructed to withstand autoclaving and other severe sterilization conditions. After use, the entire sensor is discarded rather than re-sterilized and reused, ensuring reliability without requiring complex sterilization-resistant electronics.
3Measurement precision
If conventional force sensors are used, then contact force data is obtained, but tactile feedback to the operator is not provided
Solution Approach 1:
The system incorporates a feedback mechanism where the contact force measurements obtained by the sensor are transmitted to the operator in real-time. The processing unit analyzes the strain gauge data and provides tactile feedback through the robotic manipulator, allowing the operator to feel the contact force between the balloon and tissue, thereby compensating for the lack of natural tactile sensation in remote robotic procedures.
4Ease of manufacture
If reusable endoscopic devices are used, then cost is reduced, but they cannot be disposed of economically for each use due to high cost
Solution Approach 1:
The force sensor is designed as a cost-effective disposable device. The balloon and strain gauge components are manufactured using economical processes and materials that allow the entire sensor to be disposed of after a single use. This eliminates the need for expensive re-sterilization and maintenance procedures associated with reusable devices, making disposable use economically viable while ensuring each sensor starts in a pristine, sterilized state for each patient procedure.
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
Enables precise measurement of tissue compliance and contact forces during minimally invasive procedures, reducing tissue damage risks and improving surgical precision with tactile feedback, while being economically viable for disposable use and compatible with reusable endoscopic instruments.
Implementation Method 1
a gas-inflatable balloon (20), preferably made of latex, arranged to switch between a deflated state, and an inflated state at an inflation pressure
Implementation Method 2
a detector configured to output a detection signal responsive to a contact force-related value related to a contact force acting on the gas-inflatable balloon
Data Source
AI summary
A contact force sensor device (10) comprises a gas-inflatable balloon (20) 5 arranged to switch from a deflated state (D) to an inflated state (J) in which it protrudes out of a support member (11); a valve assembly (34) to inflate/deflate the gas-inflatable balloon (12) with a gas; a detector (41) of a force-related value related to a force acting on the inflated gas-inflatable balloon (20) including a membrane (22) due to a contact with a wall (90) 10 outside of support member (11); a processing unit (60) configured to receive a detection signal (45) and to consequently calculate a contact force signal (54) according to a predetermined function; and a notification device (70) configured to receive the contact force signal (54) and to notify it to a user. The value detected can be an excess pressure ΔP in gas-15 inflatable balloon 20, or a deformation parameter of gas-inflatable balloon 20 caused by the contact, or a strain or stress modification in membrane 22, all these effect being caused by the contact with wall 90. Due to its simple structure and small size, the contact force sensor device (10), can be advantageously used in an diagnostic or surgical instrument since, 20 deflated, it can be easily inserted into a patient's body through a very small entry site, possibly along with a surgical or diagnostic tool to perform a mini-invasive surgical or diagnostic operation.