Abstract
The monitoring of some parameters, such as pressure loads, temperature, and glucose level in sweat on the plantar surface, is one of the most promising approaches for evaluating the health state of the diabetic foot and for preventing the onset of inflammatory events later degenerating in ulcerative lesions. This work presents the results of sensors microfabrication, experimental characterization and FEA-based thermal analysis of a 3D foot-insole model, aimed to advance in the development of a fully custom smart multisensory hardware–software monitoring platform for the diabetic foot. In this system, the simultaneous detection of temperature-, pressure- and sweat-based glucose level by means of full custom microfabricated sensors distributed on eight reading points of a smart insole will be possible, and the unit for data acquisition and wireless transmission will be fully integrated into the platform. Finite element analysis simulations, based on an accurate bioheat transfer model of the metabolic response of the foot tissue, demonstrated that subcutaneous inflamed lesions located up to the muscle layer, and ischemic damage located not below the reticular/fat layer, can be successfully detected. The microfabrication processes and preliminary results of functional characterization of flexible piezoelectric pressure sensors and glucose sensors are presented. Full custom pressure sensors generate an electric charge in the range 0–20 pC, proportional to the applied load in the range 0–4 N, with a figure of merit of 4.7 ± 1 GPa. The disposable glucose sensors exhibit a 0–6 mM (0–108 mg/dL) glucose concentration optimized linear response (for sweat-sensing), with a LOD of 3.27 µM (0.058 mg/dL) and a sensitivity of 21 µA/mM cm2 in the PBS solution. The technical prerequisites and experimental sensing performances were assessed, as preliminary step before future integration into a second prototype, based on a full custom smart insole with enhanced sensing functionalities.
Highlights
The problematic of diabetic foot comprises the onset of infection, ulceration and/or destruction of deep tissues aggravated by neurological pathology and/or peripheral vascular disease in the lower limbs of patients affected by diabetes [1]
The detection capability of subcutaneous at-risk lesion is related to the limit of detection of the temperature sensors (0.1 ◦C for Maxim MAX30205): based on this assumption, finite element analysis (FEA) results demonstrated the successful detection Sensors 2021, 21, x FOR PEER REVIEWof subcutaneous inflamed lesions located up to the muscle layer, and ischemic dam12aogf 2e2 located not below the reticular/fat layer
A smart multisensory hardware-software monitoring platform for diabetic patients was presented, in which an antibacterial polyurethane-based insole was proposed as a reliable platform for integration of an array of minimally invasive and low power commercial and proprietary sensors distributed on the plantar surface
Summary
The problematic of diabetic foot comprises the onset of infection, ulceration and/or destruction of deep tissues aggravated by neurological pathology and/or peripheral vascular disease in the lower limbs of patients affected by diabetes [1]. Ischemia represents a troubling state in presence of foot infections and/or ulceration, being the blood supply inadequate to meet the increased metabolic demand of the lesion underway. This because a severe complication of the poor blood circulation is the onset of hard-to-heal wounds and sores in the lower extremities, which, if not treated early or left untreated, can entail spreading infection, ulceration and gangrene of ulcer, increasing the risk of amputation of the affected part of the lower limb [4]. While neuropathic wounds have a good chance of healing within five to six months, ischemic or neuro-ischemic injuries have a longer and more difficult progress because the blood perfusion is inadequate with respect to the demand for blood from the damaged tissue [5]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
