## 2 Materials and Methods
### Method
#### 2.6.2 Selection of IoMT Devices  
Device selection is a crucial stage in the implementation of an IoMT system. To guarantee the selection, a process is followed where it is first necessary to identify which devices are required for the IoMT system. This is done based on previously established system requirements, as shown in Table 1. Device accuracy is a significant factor to consider when selecting IoMT devices as the accuracy of the collected data is essential for medical decision-making [13]. In this case, devices with proven accuracy have been chosen according to their technical specifications. Figure 3: Measurement variable selection interface in IoMT. Based on the system requirements, devices are selected with an accuracy of at least 0.7, connectivity via Bluetooth or Wi-Fi, and a battery life of at least 48 h, as shown in Table 2. Based on this, it determines that blood pressure monitor B, pulse oximeter B, and blood glucose monitor A are the most suitable devices for use in the IoMT system as they meet the stated requirements. After selecting the most suitable devices for use in the IoMT system, it is essential to verify that they comply with applicable medical safety standards and are safe for patient use. To do this, tests and evaluations are carried out on the selected devices. First, the devices are verified for compliance with medical safety standards and regulations, such as ISO 13485 and FDA 21 CFR Part 820, which set out the requirements for manufacturing and designing medical devices. Next, device documentation, design, materials, and components are evaluated to ensure they meet standards [26]. In addition, electrical safety tests are performed, such as electrostatic discharge (ESD) resistance tests, power supply isolation, and electromagnetic compatibility (EMC) tests. Software security testing, such as vulnerability testing, code analysis, and penetration testing, is also carried out. Once all of the tests and evaluations have been carried out, it is determined if the selected devices are safe and comply with the applicable medical safety standards. It can be verified if the blood pressure monitor complies with the ANSI/AAMI BP22:1994 standard, which establishes the accuracy and reliability requirements of non-invasive blood pressure measuring devices. In addition, the device can be verified to be 95% or better accuracy in measuring systolic and diastolic blood pressure based on IoMT system requirements [27]. It can be demonstrated that the pulse oximeter complies with ISO 80601-2-61:2017, which establishes the safety and performance requirements of blood oxygen measurement medical devices. In addition, the device can be verified to be 97% or better in terms of accuracy when measuring blood oxygen saturation, according to the IoMT system requirements. Later in an IoMT implementation, it is necessary to evaluate the sustainability of the selected devices based on factors such as durability, energy efficiency, and ease of maintenance. This ensures that the selected devices are sustainable in the long term and minimize operating costs [28]. For durability, the selected devices are estimated to have a useful life of at least five years, which is considered adequate to mitigate the need for frequent device replacement and reduce the costs associated with acquiring and disposing of obsolete devices. In addition, the devices are estimated to have low power consumption, long battery life, and the ability to run on renewable energy sources, such as solar panels or rechargeable batteries. These factors contribute to the energy sustainability of the IoMT system and reduce the associated energy costs. Finally, regarding maintenance, it is estimated that the devices are easy to maintain and repair in case of failure, reducing the need for frequent appliance replacement and lowering repair and maintenance costs.