Smart Shoe Insole Based on Polydimethylsiloxane Composite Capacitive Sensors

Abstract

Nowadays, the study of the gait by analyzing the distribution of plantar pressure is a well-established technique. The use of intelligent insoles allows real-time monitoring of the user. Thus, collecting and analyzing information is a more accurate process than consultations in so-called gait laboratories. Most of the previous published studies consider the composition and operation of these insoles based on resistive sensors. However, the use of capacitive sensors could provide better results, in terms of linear behavior under the pressure exerted. This behavior depends on the properties of the dielectric used. In this work, the design and implementation of an intelligent plantar insole composed of capacitive sensors is proposed. The dielectric used is a polydimethylsiloxane (PDMS)-based composition. The sensorized plantar insole developed achieves its purpose as a tool for collecting pressure in different areas of the sole of the foot. The fundamentals and details of the composition, manufacture, and implementation of the insole and the system used to collect data, as well as the data samples, are shown. Finally, a comparison of the behavior of both insoles, resistive and capacitive sensor-equipped, is made. The prototype presented lays the foundation for the development of a tool to support the diagnosis of gait abnormalities.

In-shoe plantar pressure measurement technologies for the diabetic foot: A systematic review

“…This review identified several types of technology integrated into the proposed measurement systems, including resistive technology [ 44 , [53] , [54] , [55] , [56] , [57] , [58] , [59] , [60] , [61] , [62] , [63] , [64] , [65] ], piezoelectric [ 39 , 40 , 46 ], capacitive [ 41 , 52 , 66 ], inductive [ 49 , 51 ], fiber optics [ 38 , 50 , [67] , [68] , [69] , [70] , [71] , [72] ] and textile technology with piezoresistive features [ [73] , [74] , [75] ]. In Fig.…”

Microsphere-Structured Protein Hydrogel Dielectrics for Capacitive Wearable Sensors

“…The advent of intelligent devices has stimulated efforts to improve the quality of life and, in particular, to the rapid development of wearable electronic devices. , Flexible wearable sensors with excellent portability and ergonomics have attracted considerable attention as medical monitoring devices, , intelligent robots, and wearable sensors. , Sensors based on the capacitive principle offer the advantages of easy setup, high intrinsic frequency, reduced hysteresis, and high pressure sensitivity compared with resistive and piezoelectric sensors . However, conventional dielectric layer materials for capacitive sensors are often made of silicone materials , and synthetic polymers, , which are problematic in terms of fit and biosafety . Hydrogel-based materials have emerged as a preferred choice due to their simple preparation, high accuracy, fast response, good repeatability, and wearability.…”

“…6,7 Sensors based on the capacitive principle offer the advantages of easy setup, high intrinsic frequency, reduced hysteresis, and high pressure sensitivity compared with resistive and piezoelectric sensors. 8 However, conventional dielectric layer materials for capacitive sensors are often made of silicone materials 9,10 and synthetic polymers, 11,12 which are problematic in terms of fit and biosafety. 13 Hydrogel-based materials have emerged as a preferred choice due to their simple preparation, high accuracy, fast response, good repeatability, and wearability.…”

Steganography in IoT: Information Hiding with Joystick and Touch Sensors

“…Input devices collect data from the environment. They may measure temperature [ 46 ], medical parameters [ 47 ], displacement [ 48 ], pH [ 49 ], pressure [ 50 ], humidity [ 51 ], inertia [ 52 ], etc. Output devices broadcast messages to the external world.…”