FEATURE WEARABLE ELECTRONICS
The age of biometrics and wearables is upon us
Matt Cook from Solid State Supplies looks at what makes a wearable device successful as well as some of the technologies that are advancing this market space
T
he market for wearable devices – especially biometric monitors – is
growing rapidly and consumers are becoming more accepting of the technology, and more likely to buy at least one. In an increasingly competitive market space manufacturers are striving to find ways to make their devices more engaging so that consumers buy and continue to use them, eventually replacing them with an updated version. This is what marketing people call ‘stickiness’ and at its heart is convenience that is delivered through elegant and advanced technical solutions that meet ever-increasing consumer demands.
According to a recent study by PwC, 76% of people are likely to purchase a wearable device within the next year, with fitness bands being the most popular (57%). In fact, improving health and extending lifespan is one of the most often perceived benefits of the technology.
The report also discusses the reasons
behind decreased usage among current owners. The primary reason is productivity – which is closely linked to convenience for the user. In terms of mobile fitness devices convenience and productivity is related to the features, size, weight, time between charges and connectivity of the device. Wearable technology continues to carry a relatively high price tag and, in order to invest, consumers are demanding devices that are small, unobtrusive, highly featured, connected via a mobile device and with several days between battery charges. While this is clear, many of these requirements in fact conflict with each other (long battery life requires a larger battery, but users want smaller devices) giving designers a real challenge. Fortunately, Solid State Supplies is responding to the challenge and bringing to market devices that are allowing designers to meet the demanding needs of consumers. With connectivity being crucial to allow personal data from wearable devices, this is naturally a key area for advancement. The Bluetooth standard itself has developed with the latest versions offering a significant number of low power features.
30 MARCH 2018 | ELECTRONICS Figure 1:
Wearable fitness devices are becoming popular as people become more health-conscious
Taking advantage of the features offered Figure 2:
The Blue Gecko SiP from Silicon Labs is the world’s smallest fully certified Bluetooth module
by the latest incarnations of Bluetooth is Silicon Labs’ BGM11S Blue Gecko System- in-Package (SiP) Bluetooth module. This device is the world’s smallest, fully certified Bluetooth SiP module and is ideal for wearable applications where ultra-small size, reliable high performance RF, low power consumption, full modular certification and easy application development all ease the designer’s task. Measuring just 6.5 x 6.5 x 1.4mm, the BGM11S module fits where other certified Bluetooth modules are simply too big. The Blue Gecko SiP integrates a high performance, ultra robust antenna, which requires minimal PCB, plastic and metal clearance, further reducing the required PCB area to only 51mm². From a software perspective, there is a Bluetooth 5 compliant stack as well as the ability to run end-user applications on-board or alternatively the device can be used as a network co-processor over one of the host interfaces. A metal shield enables full modular certification for WW regulatory compliance.
A key feature of the SiP is its excellent
low power performance, consuming just 8.7mA while receiving @ 2.4GHz. The DeepSleep current of 2.5μA (full RAM retention and RTCC running from LFXO) ensures a long operating time for wearable devices, even when powered by a coin cell. The Si117x Biometric Optical Sensor from
Silicon Labs is the lowest power optical heart rate (HR) sensor available. The small (3.7mm x 7.0mm), integrated module supports up to 4 distinct LEDs (all of which can be simultaneously driven), thereby simplifying optical design. When in standby mode, the sensor consumes <500 nA, thereby further reducing the system power requirements. The devices also support Silicon Labs proprietary, motion compensated HR algorithm that is optimised to run on the Gecko platform. The high level of integration enables power and performance to be optimised at the system level as well as reducing time-to-market for designers. The Si1172 and Si1173 versions include a built-in ECG front-end that allows single channel ECG measurements alongside optical HR, allowing designers to add additional value to products by gathering more physiological information. Completing the suite of devices for
wearable applications is the Si7051 digital temperature sensor, also from Silicon Labs. This device offers low power consumption of just 195nA when sampled once per second. The Si7051 features a band-gap temperature sensor element, a 14-bit analogue-to-digital converter and an I2
C
interface, all within a 3.0 x 3.0mm DFN package.
The use of patented novel signal processing and analogue design enables the sensor to maintain accuracy over a wide temperature and supply voltage range. While the design of compelling biometric
wearable devices is challenging, through careful selection of semiconductor devices, such as these from Silicon Labs, in many cases, the designer’s task is becoming much easier.
Solid State Supplies
www.sssltd.com T: 01527 830800
/ ELECTRONICS
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