Suppose we use the example of a typical mobile patient monitoring device aimed at monitoring a patient's vital signs such as body temperature, blood pressure, ECG, oxygen saturation, or respiratory rate via sensors. In that case, these are the typical challenges to be considered:
Medical devices are subject to strict safety standards and usability guidelines. One essential consideration is thermal management, in which the IEC60601-1 standard regulates the surface temperature for medical devices. For devices in contact with the patient's skin, this entails that the device's surface temperature must stay below a specific temperature, which depends on the exact device application. Thermal simulations are an integral part of the design process. For example, simulations can help identify "hotspots" and the device construction might need changing to distribute the heat more evenly or modify the material for individual components.
In today's battle for quick time-to-market to beat the competition, advanced simulation capabilities provide a considerable advantage as they can be done virtually without the need for early-stage prototypes. This way, it is possible to try different materials and construction set-ups within a short time frame to see how they affect the surface temperatures.
Material selection is typically among the early steps when designing the device. Medical devices often require the use of non-allergenic materials, which are also very robust and have high endurance to sustain continuous cleaning or contact with chemicals. Also, the material might need to be RF transparent to transmit radio frequency (RF) signals. The easiest solution to making sure the material choice fulfills all compliance requirements is to use pre-certified materials for medical usage. Working with an R&D team with a comprehensive material database and simulation capabilities as described above, can streamline the material selection process considerably.
The long service life required of many medical devices poses challenges for their mechanical endurance. Problems caused by poor mechanics quality (the design and/or manufacturing process), coupled with contact to chemicals in daily use, can lead to breakages or fractures on the device. A carefully considered design, competent manufacturers, and thorough testing can prevent such problems. In addition to the visually appealing design, quality assurance and assessment are essential.
Protection against electrical hazard
Accessible parts of the device must be protected against leakage current as regulated by the IEC60601-1 standard. It contains special requirements for medical equipment, which constitute a significant deviation from consumer products. If a risk of leakage current gets identified during the design process, accessible conductive parts of the hardware need to be exchanged or secured with additional components to prevent this from happening. Also, medical devices require a measuring function for leakage current and a control mechanism so that the device will switch off automatically if a leakage current occurs or exceeds certain limits.