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System Prototypes may look ugly, but they sure do work!

In this series of posts on prototyping, we explore how wearable technology is created. Through tried and tested prototyping iterations, we look at how to deliver game-changing wearable technology products from idea to mass production.

Every product is different, but the processes for creating them share many similarities. Choosing appropriate prototyping for a given stage of development is key. Coupling this with deploying a wide range of available prototyping technologies and techniques will rapidly deliver impact, reducing risk in a controlled way and stress-testing the product proposition at each stage.

  1. Feasibility Prototype

  2. Form Factor Prototype

  3. System Prototype

  4. Concept Prototype

  5. Production Prototype

Why a System Prototype?

Creating a System Prototype gives us the opportunity to create a fully functional prototype of the system without needing to miniaturise everything. It’s a rapid and effective way to deliver full performance and provide a platform for optimisation of power usage and software development for the final product, since all the final key components to be used are tested here.

The System Prototype often comprises off-the-shelf ‘development kits’ with sensors, processors and wireless technologies, modified and wired together to represent functionally how the eventual product will work. It involves building out the essential digital elements on mobile devices and the cloud, to confirm how the ecosystem will operate. Critical development is achieved with this platform and, although it looks little like the vision for the product, it can be programmed, collect data and connect to the outside world in a way close to how the final product will perform. 


While the aesthetics and ergonomics are developed through the Form Factor Prototype, discussed in our last post, System Prototype development can be progressed in parallel to provide a platform for functional development of the product. The engineer can procure and connect proposed system parts and install code to start the data flowing. This is critical in understanding which components will eventually make it into the product.

Reducing the focus on the size and integration of the functional elements of the system allows rapid and cost-effective development. Off the shelf, development boards can be used to test system architecture and functionality and this removes much of the need for commissioning bespoke, miniaturised physical electronics.

After the initial system has been selected and built, the essential functionality can be clearly understood. Refinements are made through development and testing, providing increasing clarity of the data and data flows. When the System Prototype reaches a stable and finalised form, the resulting components connected together will represent the component list for the first integrated Concept Prototype of the product, which we will discuss in a subsequent blog and the real-world functionality of the end product is clearly represented.

Whilst Functional and Feasibility Prototypes are excellent at advancing important elements of a future product, addressing the Form Factor Prototype separately, confirms how the future product should look, feel and be worn. This also sets targets for future miniaturisation of the electronics and battery size optimisation. In combination, this makes the commercial and user proposition much clearer, engaging stakeholders and investors.

Examples of this prototype in the real world

When developing a System Prototype, we will normally consider several categories of technology in tandem, each of which needs to complement the other and will likely be subject to changes as testing and development progress. The basic physical elements will normally be:

  1.  A set of sensors, such as a PPG (Heart Rate Sensor), a movement sensor (such as an accelerometer), a touch sensor (such as a capacitive touch surface). In practice, at Thrive some of our work takes these kinds of standard sensors to new levels, and at other times we work with entirely new sensor technology

  2.  A processor (or processor family) (such as an Arm Cortex, Raspberry Pi, or Atmel Microcontroller

  3.  A wireless system (such as a Bluetooth, or WiFi chip)

  4.  Power (such as a Lithium Batteries and management circuits)

Each of the above will be selected based on the expected performance characteristics. Sampling rates, algorithms, connectivity all have a significant effect on the performance of the system and hence the design, so each element is very much subject to change as more is understood. Other elements might be included, such as fabrics and other mechanical elements and -bespoke parts established through Feasibility Prototyping.

These days we are often able to procure most basic circuit elements on ‘development boards’. These off the shelf circuit boards have the silicon, basic power supplies and a large range of connection points. Development  boards can be wired together rapidly to establish a system prototype and then rapidly reconfigured to flex with changing requirements and as code is developed.

User testing and validation

A system prototype can be used to produce real data, so it can assist with early trials with users. For example, the bulky System Prototype electronics can be housed in an auxiliary case and attached to a person to capture data. This may not give the full user experience but will allow high-resolution data to be collected. It is often desirable to capture data at higher rates and potentially with additional sensors at this stage, where there is an interest in establishing which sensors give the most appropriate data to drive the product value proposition.

Cost and value for money discussion

The unit cost of the System Prototype is not representative of the eventual product, but careful consideration is paid to selecting components that are readily available and well documented. As the system prototype matures, more attention is paid to the specific functional elements in operation, considering whether similar, but cheaper variants will be available to perform the required role. Where the savings come from are in the fact that little or no bespoke electronics design is required to create a System Prototype. This reduces delivery time and design costs considerably. The completed System Prototype confirms the key components for the product, which allows a bill of materials for the final product to be built and the unit costs of the product can be projected more accurately.

Physical/Digital/Data nuances

A System Prototype is not restricted to the physical device. The connected digital services and algorithms should also be considered, although they may be crudely rendered at this stage. For example, if the product will eventually be driven by Azure in the cloud, we would likely connect the system prototype to a basic Azure platform, allowing data flows to be established and debugged. No attention would yet be put into developing fancy visual interfaces or user connections to the system. The focus is instead on the ongoing data science and value creation as the System Prototype collects data.


A System Prototype allows rapid development of the functional device. It collects data, connects to other essential infrastructure, opens up the possibility of algorithm development and establishes an important building block in the design and development of a wearable technology product.

In combination with Feasibility Prototypes and a Form Factor Prototype, it sets the scene for creation of a Concept Prototype, which we will discuss in our next post. The learnings and refinements to the system at this stage are essential, specifically including performance characteristics, a good understanding of power requirements and hence an estimate of battery size and product cost.

We spend our time putting this process to the test through creating products. Some nice examples of this are available on the WORK page of our website. If you have any questions or comments, please get in touch, or email us here.

Article by Dr Jacob Skinner, CEO, Thrive Wearables

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