In the Netherlands there are about 800.000 patients with Diabetes Mellitus. This number will increase till 1.300.000 in 2025. Due to physiological changes high pressure spots come forward. Neuropathy, as a complication of Diabetes Mellitus, decreases the proprioceptive feedback, so people do not feel these high pressures and it increases the chance on an ulcer. 3% of the Diabetic people develop a foot ulcer, figure 1.

Treatment of these ulcers is very intensive and costly. On average an ulcer needs 5 months to heal. In 15% of the patients with an ulcer an amputation of foot/lower leg is needed. One treatment strategy is to decrease the pressure at high pressure spots on the foot sole. Insole foot pressure measurements are used to indicate high pressure spots on the foot sole, figure 2. These measurements are used by the orthopaedic shoe technician to adapt the individual insoles. Use of these insoles results in lower incidence of new ulcers. The regular insole measurements, figure 3, are mostly performed in a gait laboratory before and after adaptation of the individual insoles. Often the average pressures of 5 to 10 steps are used. However, the foot is changing rapidly and many factors influence the existence of high pressure spots. People with Diabetic Mellitus are advised to perform excellent foot care and to use special, optimal fitting shoes without stitches that can cause high pressure spots.

Figure 1, foot ulcer

Figure 2, pressure spots

Figure 3, insole for pressure measurement

The aim of this project:

1. Study on accuracy and suitability of the existing pressure and shear sensor.
2. Development of an insole that incorporates various sensors.
3. Design of a data acquisition algorithm.
4. Selection of a data storage system.
5. Design of a low-energy, wireless data transfer system.
6. Selection of a power supply.
7. Test of the insole with volunteers and comparison with existing pressure measuring insoles.
8. Test of the insole with patients.
9. Results part 1 will be published in articles and a dissertation.
10. Development of an automatic adjustment system in which specified small parts of the insole surface can rise or descend, depending on the pressure and shear measured.
11. A control algorithm will be developed for the automatic adjustment system.
12. Lab test of the automatic adjustment system.
13. Clinical test of the automatic adjustment system.
14. Final test of the entire system in a clinical trial.
15. Results will be published in articles and a dissertation.
16. Two patent applications will be written and submitted.