Reliability and Customer Expectations MUST Drive Wearable Electronics Design

Posted by Chris Montgomery on Jul 20, 2016 10:30:00 AM

Wearables-Design.jpgWearable devices are one of the fastest growing industries today. In fact, the market is expected to reach 12.6 billion in 2018 from nearly 0 in 2010! An amazing 20% of all Americans are sporting some type of fitness tracker or smart technology for personal or professional use. Unfortunately, ease of use is a key purchasing factor but nearly 83% of consumers report having difficulty using their device. Since these devices are such a big part of their lives, consumers have very definite performance and reliability expectations – and that means designers and engineers need to meet the challenge.

When it comes to wearables, reliability expectations + use environment = appropriate material and technology selection. Too often, that equation just doesn’t balance.

Reliability Expectations

Reliability is typically expressed as a failure rate at 12 months, but consumer expectations are very different. Customers anticipate running shoes to last through 600 miles of wear, watches that keeping on ticking for up to 20 years, and cell phone upgrades to happen between 12 and 36 months. If these arbitrary lifetime expectations are met, customers are satisfied; if not, the product failed in their eyes. In reality, it likely failed well before that – in the manufacturer’s design phase.

It becomes even more challenging when a new technology doesn’t have a comparable. For example, should the Apple Watch be expected to last 20 years like a good wristwatch or 18-36 months like a mobile phone? Fortunately, revolutionary or never-seen-before technologies have the opportunity to set customer expectations. 

Use Environment

Due to the relative newness of wearable electronics, use cases for this technology haven’t been defined in any appreciable way. Wearable devices are subject to certain conditions that aren’t applicable to other electronic devices, making materials selection much more critical. Designers and engineers must identify device components that can withstand or respond to uniquely human criteria like: 

  • Skin irritation: Elements regularly used in electronics, like nickel, can cause significant reactions on the skin
  • Perspiration: Sweat can corrode wearable devices, the severity of which varies by ethnicity, gender and genetics
  • Sunscreen/lotion/etc.: The type and amount of foreign substance can break down wearables’ external and internal constructions
  • Skin and hair variations: The texture and density of skin and hair vary by ethnicity, gender, genetics and impacts wearable functionality
  • Bending and flexing: The joints in the human body can be collectively bent and flexed well over 1,000 times per day

Similarly, there are distinctive environmental conditions that impact wearables and the materials from which they are made:

  • Vibration: The location of the wearable on the body dictates vibration. A device attached to a shoe, for example, is subjected to significant shock and vibration as compared to a head-mounted device
  • Temperature: Extreme temperatures, particularly cold weather, warrant special consideration for durability
  • Water: Hand washing, water immersion and rain are common moisture-related challenges that devices frequently encounter
  • UV exposure: UV ray strength varies by geography, but it can break polymeric chains when combined with temperature fluctuations and excessive moisture
  • Laundering: Wearables attached to clothing are often forgotten about on laundry day, and run through washing and drying cycles
  • Cleaning fluids: Cleaning fluids present both a moisture and chemical threat to wearables


Wearables are wireless, meaning they compete for radio frequencies and “air space” with each other and virtually all Internet of Things (IoT) technologies. This presents challenges to design fundamentals and product reliability in three key areas: 

  • Reliability assurance: Basic wireless reliability is based on determining how much signal the receiver collected from the transmitter, known as power budgeting. Designers and engineers must factor in gain, frequency, the path loss exponent and FCC limitations to efficiently manage signal power and its impact on product reliability.
  • Reliability prediction: Sophisticated tools are available to perform wireless reliability predictions but the majority is time-invariant, so there is no way to capture, monitor and manage product degradation
  • Reliability validation: Government-mandated testing focuses on radiation emission and interference compliance and has little, if anything, to do with reliability. Generally speaking, once the required tests are passed, manufacturers consider the product successful and do not pursue reliability validation.

Because of the complexities, unique environmental factors and challenges as diverse as humans themselves, simulation is absolutely essential. The more simulations and variables tested, the more likely the product will meet consumer expectations. 

Designers and engineers can introduce simulation into their processes through Sherlock Automated Design Analysis™ software. Nearly all of the variables that affect wearable electronics can be simulated, quantified and used within Sherlock to reduce product failure, without using customers as guinea pigs.

Find out what Sherlock can do for you! Request your free three-week trial now by clicking the button below.

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Topics: Design for Reliability

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