Connectivity will be key to expanding the world of wearables in the future.
The world of technology is going through another transformation. We went from mainframes to desktop PCs in about two decades; from desktops to laptop PCs in one; and from laptops to smartphones and tablets in less than that. Another revolution is brewing, and it will most likely take less than a decade to happen: Always-connected smart wearables.
Special Connectivity Solutions are Enablers
Connectivity solutions will enable the consumer electronics developers to make wearables. Standard connectors may not fit into wearables due to size, aesthetics, and technology. Eyewear needs to be thin, lightweight, and aesthetically pleasing. A watch or any other wearable often must meet the same criteria.
From a technology standpoint, customers want hermetically sealed devices so they can perform well underwater or can resist sweat, dust, and other foreign objects. Contactless solutions can address these issues.
Real estate is also a huge challenge. Eyewear and other wearables are designed with minimum space for other non-essential functions. To address these challenges, key connectivity industry players are designing solutions for wireless power charging and contactless data transmission.
Technology experts see a trend of “increased sensing.” There either will be more functionality in the same space or the same functionality in a smaller form factor. Thus, providing power is a huge challenge as well as an opportunity.
There are two main hurdles to overcome in wireless charging. The first is charging from a distance, where devices are not tightly coupled, making the goal to achieve spatial freedom. The second challenge is the design of the coil (inductor or antenna) and how to make it fit inside the tiny and complex-shaped devices.
A combination of better battery technologies (flexible, thinner, lighter, faster) and power “harvesting,” whether it uses solar, mechanical movement, body heat, or other means, is being looked at by startups and established companies in Silicon Valley and other places around the world.
Contactless data is achieved with electromagnetic radiation. It requires close proximity between the cable and the device. It is also referred to as short-range communication and is done at extra-high frequency (EHF) – 60 GHz band using the ISM (industrial, scientific, and medical) bands, a non-licensed spectrum. It is used to penetrate plastic and is compatible with USB, VESA, and SATA standards. The challenges are high-power requirements and a need for intelligence to wake up and sleep. It also requires RF expertise for robustness, low electromagnetic interference (EMI), and regulatory compliance such as with the Federal Communications Commission (FCC).
For external input/output (I/O) components, antennas have played a big role in providing freedom from wires. Almost everything is going mobile. For example, one of the largest global antenna suppliers ships more than 500 million antennas every year. In the wearable space, the challenge is the shape and size of antennas, which are becoming smaller and more complex.
The solution is to make antennas using traditional methods as well as technologies like MID (molded interconnect devices) and LDS (laser direct structuring) for 3D antennas. Some new antennas are designed using multiple protocols, i.e. LTE, Bluetooth, and Wi-Fi, among others.
Other Connectivity Components
Board-to-board connectors that connect multiple PCBs (rigid and flexible) are getting smaller, with pitches as small as 0.35mm. Current can range from 1.5A for power and 0.3A for signal. Retention force can be as high as 10N while insertion force can be 15N max.
Board-to-flex connectors are very useful for devices with height constraints. As mobile device complexity and functionality increase, there is a growing need for thinner devices with multiple antennas, higher data rates, and increased operating frequencies. EMI shields are stamped one- and two-piece metal cages that help provide isolation of board-level components, minimize crosstalk, and reduce EMI susceptibility without impacting system speed.
For charging, docking, and grounding, Pogo pins are used because of their excellent reliability and durability in a small form factor. Spring fingers are used for grounding to prevent EMI noise and static and isolation from vibrations. They can be used with a low force of 0.2N to 1.0N.
SIM-card connectors could become an essential part of wearable devices, such as mini-SIM (2FF), micro-SIM (3FF), and combined micro-SIM and micro-SD connectors.
The future is bright for smart wearables. Unique interconnect product offerings from leading industry players will certainly help this exciting revolution.
Author Samir Vasavda is a field application engineer for TE Connectivity Ltd. and is based in Menlo Park, Calif.
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