The ‘Knot patch’ personal stress sensor: from design spec to functioning PCB
01 November 2019

Knott-patch-personal-stress-sensor_Sensor-on-arm_Newbury-Electronics_Trevyn Rayner-Canham
When Trevyn Rayner-Canham, a BA Industrial Design & Technology student in her final year at Brunel University realised that she needed guidance with regard to the electronic elements of her personal stress sensor design, she turned to Newbury Electronics.
This case study was originally featured in the November 2019 issue of EPDT magazine [read the digital issue]. Sign up to receive your own copy each month.
With her project deadline looming, Trevyn needed to work with a company that could translate her rudimentary design specifications into a fully functioning PCB – in just one week...

Knott-patch-personal-stress-sensor_Sensor-on-stomach_Newbury-Electronics_Trevyn Rayner-Canham
The initial mock-up electrical circuit was fabricated using connected stock electronics. However, after discussing the requirements in more detail, Trevyn realised that using micro-electronic components would deliver a far more precise level of biodata capture. The challenge then was to get the board not only manufactured in time but, also to ensure that the finished electronic component would still work within the specified form factor that was key for the aesthetic aspect of the sensor design. This is highly unusual as typically, most electronic products have to be designed to fit around a PCB design.
Trevyn explains further: “The function of the fabricated PCB is to detect when an individual is experiencing acute fear or stress. It does so by collecting biodata through the corresponding sensors on the PCB. In this way, it can function as a discrete and automatically triggered personal safety device, potentially alerting the user’s contacts and transmitting their GPS location, according to preferences set in the accompanying app.

Knott-patch-personal-stress-sensor_Sensor-on-wrist_Newbury-Electronics_Trevyn Rayner-Canham
“I had previously made a mock-up electrical circuit for my project. However, the functionality of the final PCB far exceeded that of my mock-up (which contained all the same components, but in the form of connected stock electronics instead of microelectronic components). The final PCB can sense the required biodata with a level of precision I thought impossible. I put this ‘miracle’ down to the Newbury Electronics team and the company’s PCB design and fabrication capabilities.”
Looking ahead, Trevyn hopes to progress with the product (which she has termed the ‘Knot Patch’) by cultivating the design and ensuring that it is sufficiently developed for the health wearables market.
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