BME520 Biomedical Devices Design and Troubleshooting - Chapter 1 PDF

Biomedical Devices Design and Troubleshooting (BME520 ) Chapter 1: System Engineering - Implementation Claudio Becchetti, 1th Edition Dr. Qasem Qananwah 7/27/20...

Biomedical Devices Design and Troubleshooting (BME520 ) Chapter 1: System Engineering - Implementation Claudio Becchetti, 1th Edition Dr. Qasem Qananwah 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 1  Chapter 1: System Engineering Implementations Example : The ECG The implementation parts of this book show how the theory sections are translated into a real medical instrument placed on the market. The implementation parts show the design of an electrocardiograph (ECG or EKG) manufactured by Gamma Cardio Soft (www.gammacardiosoft.it). Gamma Cardio Soft has the vision for supplying low-cost high- performance devices, disclosing the devices’ implementation details. 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 2  Chapter 1: System Engineering Implementations Example : The ECG According to the FDA classification, an ECG is ‘a device used to process the electrical signal transmitted through two or more electrocardiograph electrodes and to produce a visual display of the electrical signal produced by the heart. The ECG is used to perform the electrocardiogram test. ECG is an electrical recording of the heart used in the investigation of heart diseases. The electrical signal recording shows the electrical heart activity and is used to diagnose various cardiovascular diseases: myocardial infarction, arrhythmia.’ (FDA, 2005) By the end of this course, you will understand the design and the implementation of a diagnostic 12-lead resting PC ECG (the Gamma Cardio CG product by Gamma Cardio Soft). 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 3  Chapter 1: System Engineering Implementations Example : The ECG 1.11.1 The ECG’s diagnostic relevance The ECG is a primary instrument for preventing cardiovascular diseases (CVDs), which are the leading cause of death and disability in the world. In 2008, it was estimated that around 17.3 million deaths were due to CVDs (WHO, 2011a). It is estimated that this number will rise to 23 million within the 2030. CVDs account for 23.6% of all deaths in the world according to the FDA classification. (FDA, 2005) 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 4  Chapter 1: System Engineering Implementations Example : The ECG 1.11.1 The ECG’s diagnostic relevance The ten leading causes of death (WHO, 2011b). 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 5  Chapter 1: System Engineering Implementations Example : The ECG 1.11.1 The ECG’s diagnostic relevance In the USA, CVDs are responsible for 17% of national health expenditure. The ECG is the primary test for assessing CVD, and it is suggested as a routine examination in many cases, such as for patients over 40 years of age (Keller, 2005). 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 6  Chapter 1: System Engineering Implementations Example : The ECG 1.11.2 ECG Types 1. Holters are used to record long-term heart activity (e.g. 24-hour monitoring). They have the poorest signal resolution (technically 40 Hz signal bandwidth) and are used to discover specific diseases that do not need a high signal quality but require hours of recording for diagnostic purposes (e.g., arrythmias). 2. Event monitoring ECGs have a better signal resolution (100 Hz signal bandwidth) and are usually used in hospitals to continuously monitor critical patients and to raise the alarm in case of patient problems. 3. Diagnostic ECG are used to discover a wider range of cardiovascular diseases since they provide better signal resolution (150 Hz signal bandwidth). This course will focus on the development of this last type. 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 7  Chapter 1: System Engineering Implementations Example : The ECG 1.11.2 ECG Types The diagnostic ECG (from now on, simply ECG) is physically composed of a device that is connected to the patient’s body with 10 electrodes. The device shows the heart’s electrical activity through the plotting of 12 signals – also called ‘leads’ – that are obtained as a combination of the 10 input signals. This justifies the term 12-lead diagnostic ECG. 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 8  Chapter 1: System Engineering Implementations Example : The ECG 1.12 The ECG Design Problem Formulation The design of a medical instrument can be considered as a ‘messy’ type problem. Problem definition may, at minimum, include jointly agreed: 1) goals, 2) outcomes, 3) input, 4) assumptions, 5) risks, 6) constraints (scheduling, budget, resources, quality, requirements). 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 9  Chapter 1: System Engineering Implementations Example : The ECG market research, usually included in a business plan, has to be supplied before developing the product. The first set of objectives includes the assessment of: the business opportunity for designing and producing a PC ECG the market size and trends the legal, regulation, certification and other existing barriers the financial evaluation of competitors and competitive prices the distinctive features of similar existing products the market demand for each selected target 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 10  Chapter 1: System Engineering Implementations Example : The ECG 1.13 The ECG Business Plan The second set of objectives includes the assessment of: the client’s expectations of the product in terms of mandatory and optional features. the price target that customers are willing to pay. the preferred channel for purchase. the expected method of promotion. 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 11  Chapter 1: System Engineering Implementations Example : The ECG 1.13 The ECG Business Plan 1.13.1 Market Size and Trend The ECG global market is expected to grow to USD 4.1 billion by 2015 with a compound annual growth rate (CAGR) of 9.7% in the 2009–2015 period (Axel, 2011). A business plan must then specify what and how a market share can be targeted. Medical Device and ECG market size/trend 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 12  Chapter 1: System Engineering Implementations Example : The ECG 1.13 The ECG Business Plan 1.13.2 Core and Distinctive Features The product features may be divided into the minimum core features, also referred to as ‘threshold product features’ and distinctive features also called ‘critical success factors’. 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 13  Chapter 1: System Engineering Implementations Example : The ECG 1.13 The ECG Business Plan The following items are possible minimum core features: 1. quality and reliability of recorded data: consists of recording all the required signals (12 tracks or leads) with no error on the track plot that might lead to a wrong diagnosis. 2. safety for patients and users: guaranteed by complying with compulsory standards of safety. 3. adequate mean time before failures (MTBF): is related to the fact that an ECG is a device that is mission critical, and often safety critical. 4. user-friendly interface: if not good, will result in errors and injuries. 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 14  Chapter 1: System Engineering Implementations Example : The ECG 1.13 The ECG Business Plan The following items are possible distinctive features: 1. capability to perform simultaneous lead recording (1, 3, 6 or 12 simultaneous signals): If the device is capable of recording simultaneously all the 12 leads the test is performed in 10 seconds. In a single-channel ECG where only one lead is recorded at once, 10x12=120 seconds are required, and some patients may find it difficult to stay at rest for 120 seconds. 2. interpretation capability: to make automatic diagnosis. Doctors feel safer if their diagnosis is backed up by computer programs. On the other hand, current interpretative programs may show errors and many cardiologists do no use these programs. 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 15  Chapter 1: System Engineering Implementations Example : The ECG 1.13 The ECG Business Plan The following items are possible distinctive features: 3. display for recording preview: ECG paper is usually specific and expensive printing is also time-expensive since ECG printers are usually slow recordings are affected by artifacts that make diagnosis difficult and repetitive recording and printing are often required to have good results. 4. networking PC connection, telemedicine, healthcare standards: Examinations may be transmitted and saved in a permanent archive. The network connection also enables telemedicine functions. Once distinctive and core features are identified, technicians have to assess the associated marginal production cost and investment for development. 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 16  Chapter 1: System Engineering Implementations 1.13 The ECG Business Plan Example : The ECG Distinctive ECG features and associated costs Instead of a full implementation of the interpretation capability, tools for assisted interpretation will be included. Simultaneous recording will be postponed to a future implementation. 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 17  Chapter 1: System Engineering Implementations Example : The ECG 1.14 The ECG Design Process The following table contains the selected Medical Device European standards/regulations for the certification of the PC ECG in the European market. Similar standards are applicable in other countries (e.g., USA (FDA, 1998; FDA, 2005)) 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 18  Chapter 1: System Engineering Implementations Example : The ECG ECG design applied standards 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 19  Chapter 1: System Engineering Implementations Example : The ECG EN 980 “Device Labeling” 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 20  Chapter 1: System Engineering Implementations Example : The ECG 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 21  Chapter 1: System Engineering Implementations Example : The ECG Other harmonized standards for ECG 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 22  Chapter 1: System Engineering Implementations Example : The ECG 1.14 The ECG Design Process ECG process design. 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 23  Chapter 1: System Engineering Implementations Example : The ECG 1.14 The ECG Design Process Builds within the ECG development. V & V: Verification & Validation 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 24  Chapter 1: System Engineering Implementations 1.15 ECG System–subsystem Decomposition Example : The ECG Gamma Cardio functional scheme 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 25  Chapter 1: System Engineering Implementations Example : The ECG 1.15.1 Hardware Platform Decomposition The hardware platform can be further decomposed into analog and digital unit within the board. The analog unit handles the analog signals coming from patients. These signals are digitized by the digital unit that contains the analog to digital converters (ADC). The digital unit also has a microprocessor that controls the board and exchange messages with the PC through the firmware. 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 26  Chapter 1: System Engineering Implementations Example : The ECG 1.15.2 Software Application Decomposition The software application exchanges messages with the firmware to manage the hardware board and to perform digital acquisition of the patient’s electrocardiogram. This signal has to be stored in the PC memory. The signal is then processed and adapted according to the visualization media features and to doctor needs. For example, different vertical and horizontal scaling will be needed for PC screens, printers or remote visualizations. A graphic user interface (GUI) has to handle all the commands coming from the users. The GUI will also have the task of showing data and messages received from the other modules. 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 27  Chapter 1: System Engineering Implementations Example : The ECG 1.15.2 Software Application Decomposition The Software application subsystem decomposition. 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 28  Chapter 1: System Engineering Implementations Example : The ECG 1.16 ECG Product Life Cycle The cost of repairing errors at different design stages is exponentially proportional to the time passed from the beginning of the project. circuit simulator tools such as SPICE (see wiki for details) may plot the expected output with respect to test input signals (sinusoids, square waveforms etc.). These simulators may also estimate the effect of parasitic resistances and capacitances that are usually present in the final printed circuit board (PCB). 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 29  Chapter 1: System Engineering Implementations Example : The ECG 1.16 ECG Product Life Cycle Tests will prove that the GUI module is able to show typical ECG signals without perceived distortion. For example, a square wave may be used to evaluate phase distortion (see Figure 1.31). Other signals may be used to evaluate typical visualization problems such as incorrect scaling or aliasing. Aliasing is due to undersampling signals which cause distortion or artifacts. 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 30  Chapter 1: System Engineering Implementations Example : The ECG 1.16 ECG Product Life Cycle 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 31  Chapter 1: System Engineering Implementations Example : The ECG 1.16 ECG Product Life Cycle The following requirements are suggested to monitor throughout project: 1. signal quality (frequency response etc.)→ can test by simulations 2. electrical safety performances → Theoretical analysis & Simulation. 3. electromagnetic compatibility → Theoretical analysis & Simulation. 4. MTBF (Medium Time Before Failures) → Theoretical analysis & Simulation. 5. power consumption→ Theoretical analysis & Simulation. 6. production cost→ (materials, electronics,PCB,packaging,man- hours,testing,packaging,production) 7. computer/board hardware resource utilization by software and firmware (memory, computational power etc.) → Theoretical analysis & Simulation 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 32  Chapter 1: System Engineering Implementations Example : The ECG 1.17 The ECG Development Plan and Project Management SDP: System Development Plan. A document template for an SDP may be used so that all these issues are addressed before starting the design project. A template such as (DI-IPSC-81427A, 2000), although conceived for software, may be adapted for this purpose. You can use the attached pages for System Development Plan for your course project and graduation project. (Attached on Moodle) 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 33  Chapter 1: System Engineering Implementations Example : The ECG 1.18 IPR and Reuse Strategy for the ECG Patents give the owner the right to exclude others from making, selling or using the claimed invention in those countries where the patent is valid. Patent analysis may reveal that the product under design has innovative aspects that are worth patenting. Utility patents must have all these essential features: 1. Novelty requirement: the invention must be original and never been distributed before in the world. 2. Industrialization requirement: only inventions that do not rely on personal skills but can be reproduced through industrial processes may be patented: i. processes (e.g., the method for making plastics and software processes) ii. Machines (e.g., telephone) iii. manufactured products (e.g., books) iv. compositions of matter (e.g., chemicals, alloys and pharmaceuticals) v. new uses of any of the above. 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 34  Chapter 1: System Engineering Implementations Example : The ECG 1.18 IPR and Reuse Strategy for the ECG 3. Limited time validity requirement: patents of this type expire within 20 years. ECG is present in over 26,000 patents as shown by Google patent searches only into US patents (http://www.google.com/patents). The patent number reduces to 2000 when considering patents associated with using a PC. The ‘PC ECG’ related patents are only 26. Regarding open-source software, a typical free software copyright is depicted below: “‘This library is free software; you can redistribute it and/or modify it under the terms of the GNU Library General Public License as published by the Free Software Foundation…..” The use of free may not ensure proper product quality and safety. But, a non-free library may also be a cost-effective alternative. 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 35  Questions ??? 7/27/2024 BME520: Biomedical Devices Design and Troubleshooting Biomedical Systems and Informatics Engineering Department 36