Smartwatch Comparison Guide: The Six Key Components of a Smartwatch from Case to Glass

Introduction

A smartwatch crams in a lot of features in one and a half square inches of space at an affordable price. The wear on the wrist feels like a conventional watch or better. Smartwatches pack in notifications via smartphone communication, an array of sensors from health monitors to GPS, capability to run apps and personalization through interactive watch faces all delivered in through interactive high resolution display technology. This does come at some loss of convenience that is a given with regular timekeeping watches. Battery life is a major issue that is still to find a satisfactory answer.

This article breaks down key components that go into making a smartwatch. While not intended to be a full technical teardown (iFixit has wonderfully detailed technical teardowns of major models described with style and aplomb), it hopefully gives some context to the features used to advertise these new best selling wearables.

The Six (or Seven) Key Features (excluding price)

From case to glass these are the components that go into the building of a smartwatch.

Case

The case is the watch container. Watch cases come in stainless steel, the standard for most watches, aluminium steel, gold at the high end and plastic in budget watches.  Case design dictates the watch shape. Cases come in square and round shapes with some design contours and profiles. For example, Pebble watch features a curved profile that fits better on the wearer’s wrist.

The case also includes watch band (or strap) attachment, ports for internal built in microphone and speakers for voice control (if included) and user navigation controls such as buttons or bezels on the side. 

Bands (or Straps if you prefer)

Bands attach to the watch case and come in standard 16 mm, 20 mm and 22 mm sizes. The preferred band material matches their conventional counterparts and are available in leather, leather steel, elastomer materials. Flexible silicone bands are preferred for outdoor and sport watches. Smartwatches allow user personalization options through watch faces, providing more than one band to match the watch face. A quick release feature is provided in some brands such as Apple Watch to allow users to change bands securely without using tools.

Battery

Battery could be the number one reason that smartwatches do not succeed in taking over the conventional watch industry. From the 18-hour life for all day use of Apple Watch to 7 days for Pebble watches that use e-Paper technology, battery is dependent largely on the application usage and display (in general, the smarter the watch, the more power it consumes).  

Smartwatches generally feature sealed cases with enclosed industry standard rechargeable lithium ion polymer batteries. Smartwatches rely on wireless induction charging eliminating use of pin technology or ports on a limited surface area. Instead of contact charging,  a magnetic connector or port at the back of the case charges the battery through an internal induction coil when connected to a charging dock.

To lower user exasperation of having to look at a battery drained or switched off display, most watches switch to power saving mode, conserving batteries only to tell the time, a display feature known as “always on”.

Processing Unit

The smarts in the smartwatch are thanks to the processing circuit that includes an integrated processor (ARM processors are the most commonly used), flash storage, wireless interfaces and sensors. The watch software - the operating system, system applications and pre-loaded apps are included with some additional space for user apps and personalization. The smartwatch platform determines compatibility with the host smartphone. 

As we saw in the previous article on the industry, smartwatch lines can support connectivity to Android or iOS phones. Wireless interfaces include Bluetooth connectivity, wi-fi 802.11 and NFC (Apple Watch features NFC allowing mobile payments using Apple Pay). Recent smartwatch editions such as Samsung Gear S2 also include a SIM for 3G connectivity. 

Sensors are a key part of the smartwatch processing hardware. On board sensors can include motion detectors, ambient light sensors and notification sensors (for vibration or audio notifications from phone, when watch is out of wireless range etc.). Fitness tracking sensors can range from pedometers, accelerometers, heart rate monitor and motion detectors. GPS sensors include inbuilt gyrometers, GPS and compass.

Navigation

While most smartwatches feature touch screen displays for user interaction, it is not the only interface. Smartwatches support other forms of navigation, allowing users to scroll and switch between different applications. 

Because watches have small surface area, smart watch makers have turned to innovative ways – from the Digital Crown in Apple Watch, the rotating bezel in Samsung Gear and tactile buttons in Pebble Watch. These controls function similar to the smartphone buttons, which allow users to perform functions such as returning to home screen, using the camera and scrolling through menus. 

Display

Displays are a major selling feature of smartwatches, where, in a limited 400 x 400 pixel area, usability in all environments and battery conservation trump high definition needs. Display screens vary from AMOLED (active-matrix organic light emitting diode) displays which are at the high end, displaying full-color screen and illuminate individual pixels. OLED technology displays allow the same options but support single and multi-color screens as well. Other display technologies include LCD backlit displays and e-ink displays that use less battery and enable viewing in outdoor environments such as in bright sunlight.

Touch screen displays enable users to interact with tap or swipe or pressure touch which brings up more menu or app access options on the watch.

To conserve battery life, some smartwatches turn off the display like a smartphone. Others watches have an “always on” feature where the display shows time like a regular watch instead of coming to life on notifications or user activation.  

Glass

The cover of the watch is made of fortified glass to handle daily use. Chemically strengthened Gorilla Glass or naturally resistant material such as sapphire and sapphire onyx which are known for their scratch resistant and durability features are used in most smartwatches.

This article was a high level overview of the building blocks of a smartwatch. Many comparison and buying guides on manufacturer sites, review sites and shopping sites will feature the highlights and specifications of these components (such as this comparison from gizmag).

In the next article in the series on smart wearables, we will cover uses cases for the smartwatch.