SMART Insole designed by Gait & Motion Analysis Lab at Hong Kong’s Polytechnic University
Dr. Roy Cheung, Associate Professor in the Gait & Motion Analysis Lab, is the inventor of the 3D printed SMART insole. Roy himself is a jogger and wanted to learn about his own running stance but the expensive market price of a smart insole drove him to initiate this project.
Roy’ specializes in: biomechanics in runners, efficacy of prophylactic devices for sportsmen, and gait retraining for rehabilitation and injury prevention, and has obtained major research grants e.g. Early Career Scheme, General Research Fund from the HKUGC, Health & Medical Research Fund from the Food & Health Bureau, and Innovation & Technology Fund from the Innovation & Technology Commission.
The Gait & Motion Analysis Lab is based in the Department of Rehabilitation Sciences at the Hong Kong Polytechnic University. Research in the Gait & Motion Analysis Lab focuses on running mechanics, performance, rehabilitation, and injury prevention. It aspires to understand the interplay between the brain, neurophysical regulatory systems, and human movements during walking and running.
3D Printed SMART Insole designed by Dr. Roy Cheung.
Both traditional insole customization and smart insole creation are a complicated process with high costs that are typically only consumed by professional athletes.
Before including 3D printing, the industry’s traditional methods included:
- High production costs
- Large batch molding
- Inaccurate hand-made production
By applying Raise3D N2, the company was able to
- Reduce production time by 64.29%
- Reduce production costs by 99.5%
- Design accurate and efficient models using computer precision.
Gait & Motion Analysis Laboratory, Department of Rehabilitation
Footwear / Medical / Research
Roy T.H. Cheung
The smart insole consists of electronic sensors and a thermoplastic insole structure. The production process has three main phases including :
- Foot Scanning
- Insole Modeling & Sensor Layout / Design
- Printing / Electronics Enclosure
Roy begin on scanning a model of the foot which will be used for modeling the insole.
Using the visualized scan data in the modelling software, he can easily locate correct position on the insole by aligning insole shape with the model of the feet. Roy’s design places two pressure sensors at position of heel and second metatarsal. Bluetooth modules are also installed in the arch area.
By using a visual model and 3D printing, Roy can maximize the protection of enclosed electronics by designing an appropriate space layout and controlling the hardness of the insole with filament selection and infill rate. All components will be enclosed between layers of filament.
Roy’s insole diagram of circuitry layout
Insole printing exposed circuit slot on Raise3D N2.
If the smart insoles were created using a traditional manufacturing process, the complete smart insoles with pressure sensors would have cost an upwards 100 thousand HK dollars and would only be durable for one year.
Both traditional insole customization and smart insole creation are a complicated process. Generally, insole customization manufacturing requires:
- impression molding from foam, silicon or plaster,
- thermoforming insole material in foot impression,
- correcting the insole and finishing.
The smart insole production additionally requires insole manufacturing and circuit integration setup. The challenge is, without moulding for a large batch order, the small batch producing or prototyping can only rely on hand making which will result in a very inaccurate layout.
By applying 3D printing, Roy eliminated most processes involved in the creation of the insole. The Raise3D N2 is able directly build a final production model with customized insole geometry and will automatically leave the space and slot exposed for circuit setup. After installation, the printer will completely enclose the electronics by printing the consecutive layers over them. Labor cost, facility and equipment cost, and lead time are shortened by this automation. Most importantly, Raise3D printer allows Roy combine insole customization and circuit setup together in one print run. As a result, price of insole is reduced to 500 HK dollars from 100000HK dollars. Lead time is reduced from 2 weeks to less than 5 days. Equipment list is reduced to computer, scanner and printer instead of foam pad and thermoforming machine and grinding machine.
Partially printed insole with circuit mounted inside.
Fully printed insole with circuit enclosed.
100,000 HK dollars
500 HK dollars
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