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Similar to the development process of other types of integrated instruments, the design and development of in vitro diagnostic devices is also a systematic project. Product development does not follow a fixed pattern and must be planned according to the specific characteristics of the in vitro diagnostic equipment and the research and development team. However, from an engineering perspective, the design, testing, and development process of in vitro diagnostic devices generally undergoes important stages such as product project design, product prototype development, product finalization, and product acceptance. Moreover, due to the unique characteristics of the medical industry, in vitro diagnostic devices often require clinical trials and evaluations, as well as verification of relevant laws and regulations before going into production.
1. Product Design
The design and evaluation of the overall solution should be completed by the project manager based on relevant policies, regulations, industry standards, and regulatory documents. This process generally includes product design requirements, testing methods, testing principles, product structural composition, product functional indicators, product performance indicators, main workflow, modular structure design, product cost estimation, etc.
If the product must enter the markets of other countries or regions, it needs to meet local regulatory requirements. Then, relevant personnel review the overall plan, propose modifications or suggestions, and continuously improve it. The shape design and evaluation determine the structure, specifications, and design style of the product shape based on the structural composition and dimensions of each module. Good appearance design can help the product dominate the market, enhance its overall competitiveness, reduce production costs, and increase customer preference.
Therefore, shape evaluation is an indispensable part of the research and development process. The software system design and evaluation should clearly convey the software’s functions to developers, users, and testers. The software description should be as detailed as possible, including interface styles, user requirements, descriptions of related product requirements, relationships between software and the overall system interface, operating environment, system functions, safety requirements, etc.
Among them, the software architecture design mainly describes the types of software components and the key functional modules of the system operation; the software description document must be written in accordance with regulations, standards, and technical management principles related to software and network security. The hardware system design and evaluation first conduct patent analysis, addressing issues such as potential infringement, derivative patents, and the patentability of technical results, based on each module’s patent disputes regarding design outcomes.
Next, the development of the hardware system technical quality standard guideline manual includes a detailed description of the hardware system’s composition, system development requirements, main technical indicators, hardware demand analysis, layout structure of each module, interface design with computers, etc. Subsequently, relevant personnel will review the technical quality standard specification, propose modifications or suggestions, and continuously improve it. After passing the review, it moves to the next process.
The design and evaluation of core modules require formulating the following content: a technical quality standard guideline manual for core modules, which details the structure of the module design, the required software support, the functions to be realized, performance indicators, and the operational environment needed to form the core module design plan. Then, relevant personnel review the module project design, propose opinions or suggestions for modification, and continuously improve it until it passes the review before proceeding to the next step.
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2. Product Prototype Development
The detailed design and evaluation of the hardware system first determine the basic modular structure of the product and the approximate dimensions of each module to achieve the product’s functions and performance. Next, the software relied upon for system operation must be determined, including execution systems, interface software, and the approximate size of each module. Then, detailed designs and confirmations of mechanical drawings, circuit boards, and tools (such as the software used and its version number) are established.
The detailed design of the hardware system needs to complete the following:
(1) Electrical structure design: Determine the quantity and parameters of the selected control components and how the modules are assembled together.
(2) Physical structure design: Based on the size of electrical components, determine how to match mechanical parts and installations.
(3) Functional structure design: Determine parameter selection.
(4) Instrument selection: Based on the parameters in the component manual, determine the instrument model; or select the best-selling model with sufficient components while achieving the same function based on mainstream model designs.
(5) Drawing printed circuit boards: Design a schematic based on circuit functionality before designing the printed circuit board diagram.
(6) Review of the detailed design of the hardware system: Relevant personnel should review the detailed design of the hardware system, make changes or suggestions, and then continue to improve. The review proceeds to the next process.
The detailed design and evaluation of the software system require specifying the main business requirements of the software system, inputs, outputs, main functions, performance indicators, and operating environment; the languages, tools, and methods used in software development, as well as names, complete versions, and the aforementioned supporting and application software suppliers must be determined. At the same time, it is necessary to clarify the number of R&D personnel, development time, workload, and total lines of code, and specify the software security level, providing detailed reasons for the determinations.
The software life cycle is divided into five stages: requirement analysis, design, coding, testing, and maintenance. The detailed design of the instrument system needs to complete the following points:
(1) System hardware topology structure: Provide a physical topology diagram based on the software design specifications, describing the physical connection relationships between software or component modules, multipurpose computers, and medical device hardware;
(2) System structure diagram: Use structure diagrams to represent the relationships between component modules and between component modules and peripheral interfaces, and describe the functions, module relationships, and peripheral interfaces based on the system structure diagram;
(3) User interface relationship diagram: Describe the relationships between user interfaces, based on the user interface relationship diagram, describe the functions and module relationships of the software system, listing the relationships of each module in the system in diagram form;
(4) Core algorithm: Describe the calculation formulas and specific calculation steps used in the core algorithm;
Program logic: Display the logical flow of the program in the form of a process flowchart;
(5) Operating environment: Clarify the hardware configuration, software environment, and network conditions required for the software to run, including hardware configuration (including processor, memory, and peripheral devices), software environment (including system software, supporting software, and security software), and network conditions (including network architecture, network type (WAN, LAN, personal domain network), and bandwidth);
(6) Interfaces: Describe the interface relationships between upper and lower modules related to this program;
(7) Contraindications: Use separate software to describe software contraindications or service limitations, and software components to describe contraindications or service limitations of medical device products, while imported medical device software should describe the country of origin.
Design engineering is the activity process of expressing the design plan in physical form, including planning and vision. The relevant processes are as follows:
(1) Electrical and optical module design: Printed circuit boards are made from electrical schematics, which are primarily constructed according to the electrical performance of each component. This diagram can accurately reflect the important functions of the printed circuit board and the relationships between each component. After completing the electrical schematic design, individual components are packaged using drawing software to generate and implement a grid with the same component appearance and dimensions. Then, individual components are placed according to the size of the printed circuit board; when placing components, it is essential to ensure that the wires of individual components do not cross. While designing the wiring diagram, the wiring floor plan is first drawn according to the electrical schematic; then, based on the floor plan, the placement of electrical components is determined, and circuit boards and other components are assembled into modules according to the design diagram.
(2) Module verification: Design engineers develop module confirmation plans based on the functions and performance indicators that each module can achieve at this stage; testing engineers confirm according to the confirmation plan and issue confirmation reports.
(3) Electrical and optical module design review: Relevant personnel review the electrical and optical module design, propose modification suggestions, and continuously improve it. After passing the review, it moves to the next process.
(4) Mechanical and hydraulic circuit module design: First, determine the components based on the design, then process or purchase components according to the drawings, and assemble them into modules based on the design drawings.
(5) Module verification: Design engineers develop module confirmation plans based on the functions and performance indicators that each module can achieve at this stage; testing engineers confirm according to the confirmation plans and issue confirmation reports.
(6) Mechanical and liquid circuit module design review: Relevant personnel review the mechanical and liquid circuit module design, propose modification suggestions, and continuously improve it. After passing the review, it moves to the next process.
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Overall Instrument Design and Verification This process aims to assemble joints and functionally verify the entire machine, including the following steps:
(1) Overall instrument assembly: Assemble the electrical, optical, mechanical, and hydraulic modules according to the drawings.
(2) Initial adjustments before power-on: Before powering on, check the relative positions of each module again according to the drawings to avoid collisions and interferences after powering on. For example, check whether the internal component wiring is correct, whether the wiring is reasonable, whether fasteners are securely installed, whether moving parts rotate flexibly, etc.
(3) Overall function and performance verification: Design engineers develop preliminary verification plans based on the functions and performance indicators that the product can achieve at this stage; testing engineers verify according to the preliminary verification plans and issue verification reports.
(4) Electrical safety verification: Verify the electrical safety of the entire machine according to regulatory and national standards.
(5) Environmental adaptability verification: Verify whether the product meets the environmental requirements specified in the design input, including climate and mechanical environment baselines.
(6) Electromagnetic compatibility (EMC) verification: Verify the electromagnetic compatibility of the entire machine according to regulatory and national standards.
(7) Overall machine review: Relevant personnel review the safety and effectiveness that the overall machine should achieve at this stage, propose modification suggestions, and continuously improve it. After passing the review, it moves to the next process.
3. Product Terminal Development
Module improvement and mold development involve engineering improvements to the mold based on the final design structure. This includes packaging and label design, as well as the design of packaging containers and accessory boxes, and refining module process documents. Testing engineers prepare test cases based on the functions and performance of each module of the instrument, transforming software testing behaviors into manageable patterns while quantifying the testing work. They also prepare a list of key components and subsequently implement tests based on raw materials.
Module confirmation involves purchasing a small amount of raw materials based on the generated bill of materials and schedule. Design engineers improve the module verification plan based on the functions and performance indicators achieved by each module. Testing engineers implement verification according to the developed verification plan and keep relevant records. The module is improved based on the opinions or suggestions raised by experts during the module review process, and technical documents are updated. Overall instrument improvement involves establishing initial inspection, debugging, and aging standards for the entire instrument. Based on the experiences accumulated during the initial inspection and aging operation of the entire machine, as well as design requirements, initial inspection and aging standards are formulated to guide production. Design engineers inspect key main libraries based on the product assembly situation, design tooling, and inspect each key main library, following acceptance criteria and user manuals; if software is involved, unified coding archiving should be done.
Overall Instrument Verification This process aims to confirm the overall functionality and performance of the developed medical device product, including the following steps:
(1) Develop the overall verification plan: Based on the overall functionality and performance indicators, design engineers should refine the overall verification plan, including the overall functionality verification plan, overall performance verification plan, overall reliability verification procedures, and overall type verification procedures.
(2) Implementation of verification: Testing engineers should implement verification according to the developed verification plan and keep relevant records.
(3) Initial inspection of the overall machine: Inspect the sealing of the overall machine installation and the relative positions of each independent part and module.
(4) Aging of the overall machine: After the product assembly and debugging are completed, the overall machine will be powered continuously for a period of time (depending on the product and time) according to the requirements specified in the process documents. This aims to discover and eliminate early failures of electronic components caused by aging and to improve the reliability and usage limits of electronic devices while stabilizing overall machine parameters and ensuring debugging quality. Generally, the overall machine considers the following aspects for power-on aging: temperature, cycle periods, accumulated time, number of tests, and test blank time.
(5) Debugging of the overall machine: After debugging qualified modules assembled into the overall machine, the cooperation between modules may not be in the optimal state to meet the technical indicators of the overall machine; thus, it is necessary to adjust the relative positions and tolerance gaps of the modules to the dimensions required by the overall machine drawings, ensuring that the work related to each component is in the optimal state.
(6) Machine performance inspection: To verify whether the instrument can achieve the performance indicators of industry standards or product technical requirements and to determine whether there are performance bottlenecks in the software system for further optimization, machine performance inspection is one of the most critical links. Project inspections should comply with the performance indicator items of industry standards or product technical requirements.
(7) Software testing: Different testing software tools can be developed as needed and then used to analyze and evaluate potential issues in the testing program.
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4. Product Acceptance Review
After completing the design and development of the medical device product, the final acceptance of the product will be conducted, and clinical evaluations and other work will be carried out as needed. This process includes the following steps:
(1) Develop the overall verification plan: Supplement the overall verification plan based on the changed design structure.
(2) Implementation of verification: Testing engineers implement verification according to the developed verification plan and keep relevant records.
(3) Clinical applicability evaluation: Medical device products are clinical application products, and an analysis and evaluation of whether the design meets clinical requirements should be conducted before the product is launched. The analysis should include clinical performance and safety data (including favorable and unfavorable data) collected during the clinical evaluation period. The depth and breadth of the clinical evaluation, the types and amounts of data required should correspond to the product’s design characteristics, cutting-edge technology, scope of application, risk level, and the level and extent of non-clinical research. The clinical evaluation should confirm clinical usage information such as the product’s scope of application (e.g., applicable population, usage site, contact method with the human body, indications, severity and stage of diseases, usage requirements, usage environment, etc.), usage methods, contraindications, precautions, and warnings.
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