Why size matters in wearable technology
Simon Ward, technical manager at fastening and fixing supplier, TFC, explores the potential for wave springs in the growing wearables market.
In 1998, engineer Steven Mann built the world’s first Linux-based smart wristwatch - earning him his reputation as the father of wearable computers. Since then, companies have developed smartwatches and other wearable electronics for a variety of industries, including fitness, healthcare and manufacturing.
The Linux watch was designed to communicate wirelessly with PCs, mobile phones, and other wireless-enabled devices, allowing users to access emails and receive direct messages. As this technology became more popular in the consumer market, industry began to explore the potential of wearable devices, particularly in the medical sector. Patients can now wear highly accurate devices, such as blood glucose monitors, that give doctors more long-term data to help understand chronic diseases in more depth.
As different industries and consumers discover how wearables can help them, manufacturers are exploring new ways to design and improve these devices.
Small scale
Size is one of the biggest challenges in wearable electronic device manufacturing. As these devices become more sophisticated, integrating all the required components becomes difficult. For example, the latest iteration of the Apple Watch contains technology capable of taking the user’s pulse and has ECG functions to provide critical health data - all in a 40 mm wide case.
As the demand for these devices has increased, design engineers have had to find ways to improve the performance of these devices while reducing their size. For example, engineers have replaced coin cells with lithium ion batteries because of their improved energy density and smaller size. As end-users require more capabilities from a smaller device, manufacturers must carefully consider what components to use.
Wave springs
A wearable device such as a smart watch, is fitted with function buttons that will likely contain some form of return spring. It may also require springs to take up tolerances and maintain electrical contact. Due to space constraints, manufacturers find it impossible to fit a traditional coil spring into these small spaces so need to consider alternative solutions.
Wave springs may offer this solution as they require less than 50% of the space needed for more traditional springs. They can also be manufactured in different forms depending on the spring characteristics that are required in the application. By customising parameters such as the number of turns, number of waves, material type, and thickness, TFC engineers can design these wave springs to help manufacturers meet their product goals.
As manufacturers want to ensure that all the components feel right, it may take several iterations of a wave spring to find the optimal fit. As part of the process, TFC engineers will continually work with the OEM from initial concepts right through to SOP to ensure the optimal production solution.
Back in the early 2000s, Steven Mann predicted that wearable computers, such as his smart wristwatch, would become a common part of life in the future. Today, wearable electronics have evolved to offer a variety of applications, ranging from fashion accessories to life-saving devices. No matter the application, wave springs can play a small, yet crucial role in developing the right feel for a compact, functional, and long-lasting device.