Burgeoning Market Spurs New Components, Design Platforms for Wearables

In discussing U.S. Department of Defense spending, Illinois Senator Everett Dirksen once supposedly quipped: "A billion here, a billion there and pretty soon you're talking real money".

If you’ve been keeping up with market predictions about wearables−which include among other things connected smart watches, wristband activity trackers, smart glasses, wearable GPS and heart rate monitors, headgear, belts and even connected electronic jewelry—the notion of expenditures in the billions is familiar to you.

At the risk of making you sleepy, here are a few recent crystal ball prognostications:

• Futuresource Consulting predicts the market for wearables will grow to around $20 billion by 2017.
• Juniper Research pegs retail revenue from smart wearable devices at $19 billion by 2018, compared with $1.4 billion in 2013.
• Analysts IDTechEx expect wearables will be a $70 billion plus business in 2024 with 12,000 developers and manufacturers.
• Market researcher International Data Corp (IDC) anticipates that global shipments of wearable computing devices will triple this year to more than 19 million units.

In order for product proliferation to occur at the predicted levels, technological improvements in electronic components are needed to make it possible to create smaller, more flexible and energy efficient devices that can be comfortably worn and carried all the time.

Happily, a look around the industry shows that the necessary advances are happening. Here’s a few for instances:

Designed for wearable and handheld electronic devices using wireless communication functions Murata America’s XRCGD series of quartz crystal resonators meet the frequency tolerance requirements for Wi-Fi, Bluetooth, and radio frequency/baseband applications. The devices are housed in a hermetically sealed package that is compatible with the industry standard 2016 package size (measuring 2.0 x 1.6 x 0.45 mm—to date wearable designs have been using larger 3225 size crystal products), and are said to offer a cost advantage over other similar sized hermetically sealed packaging currently available. The series achieves a total tolerance of +/-20ppm, nominal frequencies ranging from 24 MHz to 48 MHz. The stated operating temperature is -30 deg C to +85 deg C.

TDK Corporation has what it claims is the world’s smallest Bluetooth Smart (Bluetooth 4.0 low energy, or LE) module, with a footprint of just 4.6 mm x 5.6 mm and insertion height of 1.0 mm. Thanks to its compact size, the SESUB-PAN-T2541 Bluetooth 4.0 LE module is very well suited for use in emerging wearable devices. The new module is based on TDK’s proprietary SESUB technology (semiconductor embedded in substrate). The Bluetooth IC die is embedded into the thin substrate, and all the peripheral circuitry, including a quartz resonator, bandpass filter and capacitors, is integrated on top. As a result, the new Bluetooth LE module is nearly 65 percent smaller than modules that employ discrete components, according to TDK. Its substrate layers optimally route all of the I/Os to a BGA on the module’s bottom surface, enabling designers to take full advantage of the chip’s functionality. The new module thus facilitates the hardware design process and allows easy implementation of Bluetooth connectivity simply by connecting it to a power supply and antenna.

For wearable apps, sensor makers are being challenged to deliver sensors that are smaller, thinner, more durable, more accurate, have greater stability and use less power. STMicroelectronics points out that Maxwell Guider Technology, a wearable-solutions company in Taiwan whose products track people's fitness levels, selected ST’s LSM330 6-axis inertial module and LIS3DSH 3-axis accelerometer as the foundation for its low-power motion-sensing activity trackers. Both the LIS3DSH 3-axis accelerometer and LSM330 6-axis inertial module embed finite state machines – programmable blocks that enable custom motion recognition. The two devices are said to enable Maxwell Guider Technology to develop extremely compact and accurate activity trackers with low power consumption and realistic motion analysis for applications in digital consumer, healthcare/fitness, and even pet tracking, as well as wearable sensing, indoor/outdoor navigation, augmented reality and other location-based service.

Freescale Semiconductor has created an open-source, scalable reference platform that gives OEMs the building blocks they need to rapidly develop a wide range of wearable product designs from a common platform. Freescale’s compact (38 mm by 14 mm) Wearable Reference Design Platform (WaRP) application processor board (APB) allows designers to incorporate a Freescale 1-GHz i.MX 6SoloLite ARM Cortex-A9 apps processor into a compact design that includes Bluetooth and 802.11 Wi-Fi communication, a six-axis accelerometer and magnetic sensor, and a lithium-polymer (LiPo) battery charger. There is also a USB interface that can provide power. The module includes drivers for LCD or E-ink e-paper displays.

The Freescale wearable reference design system supports the Android OS, which provides a high level of functionality, though the company notes that its hardware platform can handle a range of operating systems. Freescale’s WaRP APB is designed for a modular prototype that would typically include a daughterboard that provides additional peripherals, displays and connectors. One of the first daughter boards incorporates Freescale’s KL-16 sensor hub linked to a Freescale pedometer sensor and wireless charging system.

Engineered to promote design creativity in multiple vertical segments such as sports monitors, smart glasses, activity trackers, smart watches and healthcare/medical apps, WaRP is a result of collaboration between Freescale, Kynetics and Revolution Robotics. Kynetics provides the expertise for the platform’s software, and Revolution Robotics supplies the solution’s hardware.

Power is a limiting factor in all wearable devices and, as such, in the view of both designers and market research experts say by 2018 lithium polymer batteries are expected to be the predominant portable power chemistry in wearable electronics. There is one caveat that goes along with this prediction, however: as form factor will play a major role in wearable technology, any breakthroughs in flexible battery technology would immediately emerge with wearable electronics apps in its sights.

To that end a Rice University laboratory has created a thin film for energy storage. Rice chemist James Tour and his colleagues developed a flexible material with nanoporous nickel-fluoride electrodes layered around a solid electrolyte to deliver performance that is reported to combine the best qualities of a high-energy battery and a high-powered supercapacitor without the lithium found in commercial batteries today. The new work by the Rice lab is detailed in a recent edition of the Journal of the American Chemical Society.

The Rice electrochemical capacitor is about a hundredth of an inch thick but can be scaled up for devices either by increasing the size or adding layers, according to Rice postdoctoral researcher Yang Yang, co-lead author of the paper with graduate student Gedeng Ruan. They expect that standard manufacturing techniques may allow the battery to be even thinner. In tests, the researchers found their square-inch device held 76 percent of its capacity over 10,000 charge-discharge cycles and 1,000 bending cycles.

Researchers at the Fraunhofer Institute in Germany also are working on the power problem with the design of a flexible energy harvester that can be manufactured through a low-cost printing process. The lab’s FP7 MATFLEXEND project is developing harvesters that convert mechanical deformation into energy by using a capacitive converter, exploiting the capacitor's deformation characteristics such that capacity changes permit converting mechanical energy into usable electricity. Researchers at the Fraunhofer Institute also are trying to come up with durable materials for the energy harvester, including a flexible-by-design secondary lithium-ion battery with coplanar electrodes. Fraunhofer will integrate both components into a single device. These harvesters will be aimed at wearables in medical sensing, in sports equipment that uses sensors to measure performance and body metrics and in other consumer products. The new harvesters will be optimized for the low-frequency timing patterns and low to medium forces that arise in such applications and the plan is to integrate them into consumer garments, or into an active insole for shoes. The project runs through September 2016 with commercialization of the harvesters expected about a year after the project ends.