Medical Device Substrate Layout for Stable Isolated Patient Circuits
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Solution Overview
Problem
In medical devices with patient and ground-side circuits connected by an impedance element, such as a capacitor, the use of large-sized components like DIP-type capacitors is challenging due to the increasing proportion of chip-type electronic components, leading to manufacturing difficulties and potential cracking issues with ceramic capacitors, which complicates ensuring a sufficient insulation distance and stabilizing the reference potential.
Innovation Solution
A substrate with an insulating layer separating the patient and ground-side circuits, featuring an isolated circuit with a different reference potential and impedance means, such as chip-type electronic components, to connect these circuits without requiring large-sized components, ensuring stable reference potential and reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a DIP-type capacitor is used as the impedance element to connect the patient circuit and ground-side circuit, then the reference potential can be stabilized and noise reduced, but the device complexity increases and manufacturing becomes difficult due to requiring multiple mounting processes
Solution Approach 1:
The patent merges the impedance element (capacitor) and the insulating structure into a single integrated component. The capacitor is built on an insulating substrate that provides both the electrical impedance function and the insulation function, eliminating the need for separate mounting processes for DIP-type capacitors and reducing device complexity while maintaining reference potential stability
Solution Approach 2:
The insulating substrate serves multiple functions simultaneously: it acts as the base for mounting the capacitor, provides electrical insulation between the patient circuit and ground-side circuit, and maintains the required creepage distance. This multi-functionality reduces the number of components and simplifies the overall device structure
2Ease of manufacture
If a chip-type ceramic capacitor is used as the impedance element to simplify mounting, then the manufacturing process is simplified, but the insulation distance cannot be sufficiently ensured and cracking occurs
Solution Approach 1:
The patent transitions from considering only the horizontal insulation distance to utilizing the vertical dimension as well. The insulating substrate has a thickness that provides adequate creepage distance in the vertical direction, allowing chip-type capacitors to be used while maintaining sufficient insulation. The capacitor is mounted on the surface of the insulating substrate, and the substrate's thickness ensures the required insulation distance is achieved
3Reliability
If a large-sized single-body ceramic capacitor is used to ensure insulation distance, then the insulation distance can be maintained, but the device experiences cracking and manufacturing becomes technically difficult
Solution Approach 1:
The patent segments the insulating structure from the capacitor component. Instead of using a large single-body ceramic capacitor, the design separates the capacitor (mounted on the surface) from the insulating substrate (which provides the insulation distance through its thickness). This segmentation allows the use of smaller, easier-to-manufacture components while achieving the required insulation distance
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 solution stabilizes the reference potential of the patient circuit, reduces noise between the patient and ground-side circuits, and maintains a sufficient insulation distance without using large electronic components, enhancing the reliability and safety of medical devices.
Implementation Method 1
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
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
AI summary
A substrate for a medical device, a portion of which is brought into contact with or inserted into a subject. The substrate includes a patient circuit conductively connected to the portion that is configured to be brought into contact with or inserted into the subject, and a ground-side circuit configured to perform at least one of transmission of a signal, reception of a signal, and supply of electric power on the patient circuit. The ground-side circuit is grounded by a protective ground to ensure safety of a manipulator of the medical device. The substrate also includes an insulating layer between the patient circuit and the ground-side circuit 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 insulating layer and having a different reference potential from the patient circuit and the ground-side circuit.