From multifunctional fitness trackers and smartwatches to tiny medical devices that deliver medicine or vital information, consumers have embraced wearable technologies.

Consumers have embraced the concept of wearable devices and the industry is responding in a big way. From step counters to heart monitors, consumers have shown a strong interest in monitoring their health and tracking their own vital signs. Devices have quickly evolved from simple personal fitness trackers to medical aids that communicate directly with a user’s physician to keep an eye on serious health conditions such as heart ailments, epilepsy, and high blood pressure. These wearable technologies have become an important tool in the effort to diagnose, track, and treat disease.  

Watches Expand Their Capabilities 

Wristwatches have gone well beyond telling time and counting steps. Apple’s Series 6 smartwatch can alert wearers to irregular heart rhythms, remind them to wash their hands (and do so for a full 20 seconds), help them practice mindfulness, and connect to emergency services in the event of a hard fall. The Withings Move ECG, named best wearable at the 2019 CES, is an analog watch with a built-in ECG to detect atrial fibrillation.

Today’s smartwatches integrate nano-sized sensor technologies that can detect and measure temperature, heart rate, oxygen levels, movement, and even sensitive biodata such as the presence of drugs in the bloodstream. These sensors must be small enough to fit into the small package size of wearable technologies but sensitive enough to collect data, and they must be rugged enough to endure shock, vibration, water exposure, and other environments consumers encounter.

TE Connectivity’s MS5839 ultra-compact pressure and temperature sensor measures 3.3 x 3.3 x 2.75 mm and is optimized for applications where chlorine and saline are present, such as fitness watches. The robust, gel-filled design of the MS5839 enables operation in harsh environments while providing accurate and reliable digital measurements.

Wearable devices must be lightweight, flexible, and easy to use, and the interconnects inside of them must be tiny, durable, and often waterproof, and must comply with a number of regulatory standards. These trends are being driven by IoT, AI, big data, and miniaturization.

Wearables Go Beyond the Watch 

Biosensors collect data from patients on movement, heart and respiratory rates, and temperature in small consumer products such as earbuds, smartwatches, and wristbands, as well as medical devices like patches and oximeters. Sensing products such as the ams AS7038RB and AS7038GB sensors and the AS7030B sensor module, available from Mouser Electronics, are based on photoplethysmography (PPG) and electrocardiogram (ECG), two popular methods for heart rate monitoring and heart rate variability. These sensors measure the pulse rate by sampling light modulated by blood vessels. The AS7038RB sensor is the industry’s thinnest dedicated sensor for SpO2 measurement, at just 3.70 mm × 3.10 mm × 0.65 mm.

The ams AS7038RB and AS7038GB sensors and AS7030B sensor module, available from Mouser Electronics, combine small size, integrated functionality, and a high-performance signal chain that enables designers to incorporate vital monitoring capability into tiny wearable devices.

Patch sensors can be integrated into disposable products that patients attach to the skin and wear during a brief diagnostic period, or wear for longer-term monitoring or drug delivery, such as insulin pumps that measure blood sugar levels and provide the correct amount of insulin to diabetes patients.

Connectivity Challenges and Solutions 

In addition to protecting connectivity solutions from environmental hazards, they need to be shielded from electromagnetic interference and radio frequency interference (EMI/RFI), which can degrade the device, preventing it from operating properly. Rugged and reliable interconnects are important considerations for medical devices that provide critical data. Each wearable contains a tiny RF chip antenna that is either grounded on the PCB or another area without metal or other factors that could create interference and distort the accuracy of the signal. This is especially challenging in wearables, as the small package size leaves little room for separation.

Harwin’s S09 shield clips are for use in electronics designs where space is seriously restricted, such as wearable devices, IoT equipment (sensor nodes, data acquisition modules), and portable consumer products. An operational temperature range of -55°C to +105°C helps ensure reliability.

Harwin’s S0911-46R shield can clip is currently the smallest surface mount EMI/RFI shield clip available, covering a surface area of just 2.3mm x 1.2mm and with a 2mm height. At this size it is suitable for the restricted space of wearable electronics. The clip-based shield design eliminates the need to solder the can to the PCB, making it an environmentally friendly solution as well. The shield can is removable for inspection or maintenance and supports an operational temperature range covering -55° C to +105° C.

As wearable devices become more popular — and for medical patients, more essential — they will be expected to accomplish more in even smaller packages. Connectivity solutions will play an ever-increasing role in meeting the changing parameters for these devices and should be considered early in the design cycle.

Like this article? Check out our other Connector Basics, and Harsh Environment articles, our Consumer Electronics and Medical Market Pages, and our 2021 and 2020 Article Archives.

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