Flexible Substrate Switch for Sealed Neurostimulator
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Incorporating electrical switches with minimal moving parts into low-cost, sealed, and disposable medical devices like electronic neurostimulators is challenging due to the need for robust and reliable activation/deactivation mechanisms.
Innovation Solution
A switch configuration using a flexible substrate with printed circuits and a PCB, where an integral flexible portion of the casing is used to complete an electrical circuit upon actuation, providing tactile feedback and eliminating the need for additional springs, with the substrate retained under tension within a tortuous path to prevent unwanted movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional electrical switches with moving parts are incorporated into low-cost disposable medical devices, then switching functionality is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the switch actuator (flexible portion) and the switch contact mechanism into a single integrated flexible substrate structure. The flexible substrate integrates the printed circuit pathway, the movable contact element, and the actuating mechanism into one component, eliminating the need for separate moving parts and reducing overall device complexity while maintaining reliable switching functionality.
Solution Approach 2:
The patent replaces traditional mechanical switch components (buttons, springs, contacts) with a flexible printed circuit board that uses elastic deformation of the substrate itself to achieve contact making and breaking. The flexible portion of the substrate acts as both the structural support and the switching element, substituting complex mechanical systems with a simpler elastomeric mechanism.
2Ease of operation
If additional springs are added to reopen the switch after closure, then switch reset functionality is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The flexible substrate serves its own dual function: it provides both the conductive pathway and the restoring force mechanism. When the switch is actuated, the elastic deformation of the flexible substrate itself provides the force to return the contact to its original position, eliminating the need for separate spring components. The substrate serves itself as both the circuit carrier and the mechanical reset mechanism.
3Ease of manufacture
If the flexible substrate is not retained under tension, then manufacturing is simpler, but unwanted movement and reliability issues occur
Solution Approach 1:
The patent utilizes the elastic properties of the flexible substrate by maintaining it under continuous tension during operation. This tension state is a critical parameter that ensures the substrate returns to its original position after actuation and prevents unwanted movement. The manufacturing process is designed to incorporate this tension state, using the substrate's elastic recovery characteristics to ensure reliable contact stability while maintaining manufacturing feasibility.
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
This configuration results in a cost-effective, robust, and reliable switch mechanism that can be used to activate or adjust device parameters, providing tactile feedback and ensuring the device remains sealed against moisture ingress.
Implementation Method 1
the flexible substrate is retained by the casing under tension. For example, the flexible substrate may be disposed within a tortuous path formed within the casing, such that the substrate is retained by the casing. Keeping the substrate under tension also allows the substrate to act somewhat as a spring
Implementation Method 2
the external integral flexible portion is resilient, such that when force is applied to the integral flexible portion it is flexed into the interior of the casing, and when force is not applied, it is no longer so flexed
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A neuromuscular stimulation device is described having a plastic casing housing a printed circuit board bearing control electronics, with the casing including an external integral flexible portion which is capable of being flexed into the interior of the casing so as to cause an electrically insulative substrate on which is carried an electrically conductive pathway to be pushed into contact with the PCB in order to complete an electrical circuit. Such a switch is relatively inexpensive to produce, as it has few moving parts, can be formed in a usual manufacturing process, and is robust.