Wearable technologies that don't get in the way: a constant work-in-progress

On today's blogpost, we go down the memory lane again, but this time exploring how the usability of our Wearable systems has evolved.  

Recently, on “How INSIGHT Wearable unlocks the full power of a pressure map”, we showed you our first INSIGHT App prototype. At that point in time, we would only collect pressure data and the Wearable had a very simple design: a white box with connectors for the Sensors and a simple power switch. A VELCRO adhesive in its back was used to attach it to the socket’s outer surface. 

One of the first functional prototypes of the INSIGHT Wearable, circa 2017 

Our first field incursions with this prototype were in Portugal. That made us aware of lots of challenges: not only of the variety socket dimensions that we can find but also the variety of socket suspensions methods. We often saw pin-lock systems, seal-in liners and even suction through nothing else than bare skin, the socket and a one-way valve.  

This experience included dozens of hours in O&P clinics where we had the chance of watching not only the socket fitting process, but also the daily challenges of both amputees and prosthetists. Such an intimate look unraveled the work (and often the frustrations) that go into ensuring an amputee goes home pleased and confident with his prosthesis, while keeping its cost within budget. This implies that the prosthetist has to work together with the amputee to ensure adequate socket fitting and prosthesis alignment as well as ensuring every component necessary is at hand to manufacture the prosthesis.  

Thus, designing a usage experience empathetic with the constraints, limitations and common frustrations of both the prosthetist and the patient became pivotal to us. Right from the start, we made several design decisions towards that: 

• The Wearable should change from a box to belt concept  

Such design would spread the connectors of the Sensors along the Wearable, enabling a straighter (and easier) connection between the several Sensors spread inside the socket and the Wearable. 

• The Sensors should connect to the Wearable via USB-C 

We all have tried to plug a USB device the wrong way and we can all agree that such a frustrating experience should not be a part of a socket fitting session. USB-C connectors plug in both ways, shaving some precious seconds and frustrations off the session. 

• The Wearable should come in different sizes 

This would enable a good coverage of Sensors’ connectors around the socket for variety of socket dimensions. 

You may be already familiar with the result of these decisions: a dual device wearable system (made up of INSIGHT Wearable and Wearable IMU) supporting both pressure and gait analysis.  

The current iteration of the INSIGHT Wearable (in three sizes: 4, 8 and 12 Sensor connectors) and the small INSIGHT Wearable IMU 

We were now eager to go back into the field to test out these new improvements. In particular, we were particularly curious about the experience of setting up the Wearables, given that, due to our sensing technology, we were required to enforce some unavoidable constraints:  

• The Wearable is to be used over the socket, with the Wearable IMU in the other segment of the leg (shank/thigh). Both devices should be placed upright. 

The ideal placement of the devices in a transfemoral and a transtibial amputee: the Wearable by the socket, the IMU on the other leg’s segment, both upright. 

At this time, this felt like their most simple and useful positioning. 

• The Wearable and Wearable IMU shall be facing laterally – roughly 

A concern that drove our design was to not overburden the prosthetist with precise device positioning requirements, as common in wearable technologies. We collected data on real patients and used that to teach our system to recognize gait patterns. We further augmented that data by artificially introducing rotations, as if the device had been positioned with slight incorrections. Those steps allowed some slack in the placement of the devices while not compromising the reliability of the automatic gait characterization system. 

Possible placements of the INSIGHT Wearable/INSIGHT Wearable IMU. Our processing system were reinforced to allow small misplacements, as long as Adapttech’s logo is roughly lateral.  

We did another field incursion with this new iteration of INSIGHT, but this time into a new market: the American one. And reality did not fully meet our expectations. As we entered this new market, we were faced with a paradigm shift in suspension systems compared to our Portuguese experience. In the USA, we would find lots of patients using the elevated vacuum systems (where a sleeve is worn over both the socket and the residual limb), which hindered the use of our system.  

This figure does not in any way aim to characterize the two markets regarding tendencies in suspension systems: it is merely a graphical representation of our experiences.  

The usage of INSIGHT was impossible because of our first assumption in gait analysis: the Wearable must be worn over the socket. Under such assumption, the Sensors would have to be extremely long to wrap above the top part of the sleeve and then reach down to the Wearable.  

The only way to avoid changing the Sensors’ size was loosening our initial constraint and allow the user to place the devices in the most comfortable way: with the Wearable close to the proximal end of the sleeve, flipped upside down, to facilitate the connection of the Sensors coming out from under the sleeve. We went back and modified our gait analysis processing to detect this configuration and behave accordingly in such cases - no user input whatsoever required. 

By allowing the Wearable to be placed upside down on the proximal end of the Socket, the Sensors easily reach its connectors, no twists and turns required.  

Ever since we started the development of the INSIGHT System, we have been worried with getting to know our stakeholders: in this case, the prosthetist and amputee. The field work provided us crucial information by getting to know our clients’ personas and their daily work, as well as giving us slight hints on the ways to move forward. The evolution shown in this blogpost is a clear reminder that we should never forget that geography and local fitting practices are another important variability source. It is our goal to keep up with new challenges that may come up as INSIGHT spreads throughout the globe, in line with our ethos of being a user-centric company.