The Challenges of Wearable Electronics

• Infotainment: used to inform and entertain, including music, photos, videos, directions and e-mail.
• Activity tracking: used to monitor activities and functions such as walking, sleeping, heart rate and food consumption in order to provide individual consumers with immediate and vital feedback upon which they can take action by modifying their behavior.
• Health monitoring: used to monitor a diagnosed condition, and soon to support diagnosis, although regulatory requirements and concern for privacy mandate a long development period and testing for such technology.
• Industrial and enterprise: centers on wrist-worn terminals to provide real-time data including monitoring factory processes and updating warehouse stock. Smart glasses and bands are expected to receive rapid adoption for remote, “deskless” workers in the industrial segment.
• Soldier systems: integrate personal networks, sensors, external communications and the power to manage these systems. One goal is to link soldiers into a larger battlefield, with connectors and cable connecting subsystems required to be high performing, durable and rugged – yet light weight for soldiers who are on foot.

Sensors are an important part of wearable electronics, and continue to become smaller and more sophisticated. While there are many types of sensors that can be used, the most common is an inertial measurement unit – usually an accelerometer. An accelerometer can track a specific movement, its direction, and its intensity or speed. One simple example of an accelerometer is when a mobile phone or tablet (the input) is rotated and the device processes the movement and rotates the screen accordingly (the output).
Other common sensors including pressure, temperature, position and humidity, support applications such as compasses, GPS, and gyroscopes to detect movement. Sensors used in medical applications can be used to measure and monitor blood flow, pulse, blood pressure, blood oxygen levels, muscle movement, body fat and body weight. The most successful wearables are those that use algorithms to process raw, sensed data into actionable, meaningful insight for the user.

Wearable electronics must be able to communicate with the outside world. While wireless connectivity through short-range radio or other wireless protocols is popular, wired connectivity through a USB port is commonly required.

Many wearables have a video display or a touch screen for user interaction. A significant challenge for such small displays is ease of use. Even a high-resolution display on a smart watch doesn’t offer much real estate. Maintaining usability requires the right balance between how much can fit on the screen compared to how readable the resulting information is. Managing the power consumption of these displays is a major motivator for leading wearable manufacturers. They make wide use of low power alternatives like e-ink or e-paper as opposed to full color LCD or OLED displays. As with any electronic device, wearables must be powered by rechargeable batteries or other charging methods. This commonly requires a port for connected power to recharge the batteries. Wireless power transmission is emerging as a key feature to be integrated in new wearable devices, and presents the need for waterproofing. 

Another common hallmark of wearable electronics is the ability to run a variety of applications while an app is updated or changed. A smart watch, for example, is similar to a mobile phone. It is a computer that enables the wearer to perform a variety of tasks while connecting independently to the internet for critical app updates and downloads.

The key factor in IoT is the use of Internet Protocol (IP). IP is a communications protocol used by Ethernet and the Internet to control the flow of information. Every connected device has an IP address, giving it the capability to communicate with every other IP device. Firewalls, passwords, and other security measures control what devices communicate with each other. Wearable electronics, by virtue of an IP address, join the IoT.
One advantage to being part of the IoT is that wearable electronics do not have to exist as standalone devices. Activity data from a fitness bracelet can be downloaded to an app on a computer, which can provide a detailed analysis of trends over time in order to track progress. The music player in a watch can retrieve songs using cloud computing. The end result is that people everywhere can interact with things – TVs, homes, cars, appliances, and life-saving devices – as a result of a small device, held close to, or on our bodies – just by delving into the world of wearable electronics and the IoT.

Packaging these components into the right form factor and level of manufacturability is a challenge. As a leader in connectivity, TE works closely with designers and manufacturers of wearable electronics. Figure 2 shows typical connector solutions for a smart watch. The key feature for most of these, as well as other components, is a low profile with a small footprint. Low profile is especially important to allow the device itself to assume a slim design. 

With real estate at a premium, the integration of parts not only simplifies the system, but uses available space to maximum efficiency. Antennas can be embedded directly into the housing, as shown in Figure 3 for a mobile phone. Such Molded Interconnect Devices (MIDs) and emerging antenna technologies allow circuit traces, ground planes, and shielding to be integrated into the molded part. The substrate can be either an engineered plastic or a composite. Composites become increasing attractive in their ability to increase material strength and can be cost-effectively molded and metalized.

The drawbacks to wireless charging include lower efficiency, higher heat generation and slower charging. Each of these issues are related and will be improved by newer coil structures and higher coupling frequencies. Most wearable devices are extremely low-powered, meaning the impact of these drawbacks may be minimal.

The electronic wearable market’s challenge is to create devices that can offer useful data that will improve our lives. Whether worn on the wrist, head or foot, wearables must be fashionable, rugged, and easily rechargeable.