Medical Substrate Isolation Layout for Stable Patient Circuit Reference
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Solution Overview
Problem
The existing medical device substrates face challenges in stabilizing the reference potential of patient circuits and reducing noise between patient and ground-side circuits while ensuring sufficient insulation distance without using large-sized electronic components, particularly with the cracking issues of large-sized ceramic capacitors.
Innovation Solution
The substrate incorporates isolated circuits with different reference potentials, connected via impedance elements on insulating layers between patient and ground-side circuits, allowing for stabilization of the reference potential and reduction of noise without requiring large-sized components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large-sized ceramic capacitor is used to connect patient circuit and ground-side circuit, then the breakdown voltage capacity and insulation distance are improved, but the device experiences cracking and manufacturing becomes difficult
Solution Approach 1:
The patent divides the single large ceramic capacitor into multiple smaller ceramic capacitors connected in series. This segmentation allows each small capacitor to be manufactured without cracking while achieving the required total breakdown voltage capacity when connected in series. The multiple small capacitors also provide sufficient insulation distance between patient circuit and ground-side circuit.
Solution Approach 2:
The patent places multiple small ceramic capacitors in a nested or series arrangement within the substrate structure. This nesting approach allows the capacitors to be mounted using standard chip-type mounting processes while collectively providing the required electrical insulation and voltage capacity.
2Reliability
If a DIP-type capacitor is used as impedance element, then the reference potential stabilization and noise reduction are improved, but an additional mounting process is required beyond chip-type component mounting
Solution Approach 1:
The patent changes the physical form parameter of the capacitor from DIP-type to chip-type (SMD). This parameter change allows the capacitor to be mounted using standard surface-mount technology processes, eliminating the need for additional mounting equipment or procedures while maintaining the electrical performance required for reference potential stabilization.
3Ease of manufacture
If a chip-type ceramic capacitor is used, then the mounting process is simplified, but the insulation distance of approximately 8 mm cannot be ensured
Solution Approach 1:
The patent uses multiple small ceramic capacitors connected in series, where the combined structure of multiple capacitors and their mounting arrangement achieves the required 8 mm insulation distance between patient circuit and ground-side circuit. Each individual small capacitor is easily mounted, and their series configuration collectively provides sufficient creepage and clearance distances.
Solution Approach 2:
The patent utilizes the vertical dimension and three-dimensional space on the substrate to arrange multiple small capacitors in a configuration that achieves the required insulation distance without requiring any single component to be large. The series connection arrangement in multiple dimensions provides both electrical functionality and sufficient physical separation.
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 effectively stabilizes the reference potential of patient circuits, reduces noise, and ensures adequate insulation distance between patient and ground-side circuits, enhancing safety and reliability without the need for large electronic components.
Implementation Method 1
electrical insulation is provided between the patient circuit and the ground-side circuit
Implementation Method 2
the reference potential of the patient circuit (the patient ground) and the reference potential of the ground-side circuit are connected by an impedance element such as a capacitor in an alternating current manner
Data Source
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AI summary
To provide a substrate for a medical device and a medical device in which the reference potential of a patient circuit can be stabilized, the noise between the patient circuit and a ground-side circuit can be reduced, and the insulation distance between the patient circuit and the ground-side circuit can be sufficiently ensured without using a large-sized electronic component. A patient circuit that is a circuit on the side of being brought into contact with or inserted into a subject, a ground-side circuit that is a circuit provided on the side of performing processing on a signal transmitted from the side of being brought into contact with or inserted into the subject and protectively grounded, an insulating layer provided between the patient circuit and the ground-side circuit and providing insulation between the patient circuit and the ground-side circuit, and an isolated circuit provided apart from the patient circuit and the ground-side circuit on the surface of the insulating layer and having a different reference potential from the patient circuit and the ground-side circuit are included.