VARIASOLE

What it does

The VARIASOLE uses a customised, variable density structure to redistribute pressure evenly across the sole. This improves blood flow and can be used to treat infection, ulceration and neuropathy, particularly for those living with diabetes.

Your inspiration

A member of our team has lived with diabetes for 15 years and dedicated significant time volunteering with Diabetes New Zealand, where they witnessed firsthand the suffering caused by diabetic foot diseases. Globally, 159 million people face diabetic foot complications, highlighting a need for effective treatments. We found that current treatments were either ineffective or unaffordable. Given that 3 out of 4 people with diabetes reside in middle- to low- income areas, affordability was key. The VARIASOLE uses 3D printing to enable cost-effective, mass-customised orthotics which we hope can help reduce risk and treat diabetic foot diseases.

How it works

There are 4 steps for a patient to have their own VARIASOLE: 1. 3D Scanning: To ensure a perfect fit, a patient’s feet are 3D scanned using a LiDAR Scanner. This also allows sores and ulcers to be accommodated by the insole. 2. Pressure Mapping: A snapshot of the pressures across a patients gait cycle are recorded using a TekScan Pressure Array. 3. VARIASOLE CAD Tool: Our CAD Tool uses a pressure-reduction algorithm that analyses the pressure mapping and calculates how to distribute pressure evenly across the patients sole. It then generates a variable density lattice structure within the insole volume defined by the 3D scan to produce a digital VARIASOLE model. 4. 3D Printing: The resulting model is then 3D-printed using a soft TPU material, resulting in a custom shoe insole with Shore A hardness ranging from 28 to 44. This process leverages automation to significantly reduce the labour cost of producing custom orthotic insoles.

Design process

Our project began in 2022 with a literature review focused on unpacking the physiology of the problem and how the industry currently provides treatment. After consulting with industry experts, we established the reduction of plantar pressure as our main technical goal. We underwent detailed development in each of the four steps in the VARIASOLE Process. Our scanning and pressure mapping techniques were improved through developing tools and jigs. For example, we designed a scanning jig, which held a patient’s foot comfortably as they are scanned. The insoles are 3D printed using a foaming TPU Filament. We made and tested many TPU samples using a Shore A Durometer, exploring various parameters (for example: lattice type, wall thickness, nozzle temperature etc.) to hone the pressure reduction of these printed structures. Using knowledge from our research alongside our sample testing; we developed a pressure reduction algorithm which was implemented into our CAD Tool. There was much iteration to ensure that this CAD tool produced repeatable results. The CAD Tool was then optimised to be able produce a VARIASOLE model within seconds. Finally, we evaluated the insoles' feasibility on a diabetic patient, collecting pressure data and qualitative feedback.

How it is different

The VARIASOLE differentiates itself from existing orthotic insoles as it provides the patient with the pressure reduction of a bespoke, hand-crafted insole at a fraction of the cost. A pair of these custom insoles can be made for $20-40 NZD as there is minimal labour cost involved due to the automated VARIASOLE CAD tool and 3D-printing. This is significantly cheaper than hand-crafted orthotic insoles, which can cost upwards of $600 NZD. When tested against off-the-shelf insoles in a similar price range, the VARIASOLE performs significantly better. We observed a 70.1% improvement in pressure reduction when comparing the VARIASOLE to a similarly priced ‘memory-foam’ insole. Furthermore, the VARIASOLE recorded plantar pressure over an area 8.5% greater than that of the other insole, which suggests it is more effective at redistributing pressure. Therefore, it is clear the VARIASOLE is an effective and affordable treatment for diabetic foot diseases.

Future plans

Much work is required to bring an orthotic treatment to the market. While we had the privilege of testing this product on a person with diabetes, in vivo clinical trials with a large sample size are a necessary step to take in order to achieve regulatory clearance and will provide valuable insight into the use of this product. As LiDAR and pressure mapping tech becomes more accessible, we will look into improving the efficiency of obtaining 3D scans and pressure maps from patients –integrating these into a convenient app. From there, we can make improvements in the processing of 3D printed parts to further streamline the process.

Awards

This project was awarded a ‘Part-IV Project Award’ presented by the Mechanical Engineering Group of New Zealand. In 2022 Furthermore, this project contributed to the achievement of the ‘John McLaren Youth Award’ presented by Diabetes New Zealand to one of the team members in 2023.