An Inductive Sensor for Real-Time Measurement of Plantar Normal and Shear Forces Distribution

Du, Lei; Zhu, Xiaoliang; Zhe, Jiang

doi:10.1109/tbme.2014.2386136

Cited by 33 publications

(16 citation statements)

References 21 publications

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“…In this paper, we report on a digital triaxial force sensor based on inductive coils. The sensing mechanism builds on prior work [12], [13], introducing an integrated low-profile design with improved sensor performance and digital output. The digital output improves noise immunity in the harsh plantar environment and reduce wiring complexity in its intended application where arrays of sensors are embedded within an insole for plantar load measurements, as illustrated in Fig.…”

Section: Takedownmentioning

confidence: 99%

Design of a Digital Triaxial Force Sensor for Plantar Load Measurements

et al. 2019

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Measurement of load information on the plantar (lower) surface of the foot can provide valuable insights to help identify pathologies like diabetic foot ulcers. Studies have shown that both plantar pressure and shear stress play an important role in foot disorders, especially ulcer formation. However, in this context shear stress is much less studied in comparison with pressure distribution, mainly due to the lack of reliable measurement technologies. In this paper, we propose a triaxial force sensor for measuring plantar loading. The sensor consists of an array of sensing coils combined with an elastomeric spacer and a conductive target. Under loading, the sensor demonstrates differential variations in inductance which are digitized by builtin conditioning circuitry and decoupled. A 3D finite element (FE) model was developed for the system as a design tool. This was validated experimentally and demonstrated a high agreement to the results. In experimental evaluation with multiaxial loading the sensor showed precise operation over the operating range (RMSE: 0.05 N for shear (-1.5 N-1.5 N) and 0.70 N for normal force (0-13 N) measurements). The FE model was then used to investigate the effect of undesirable tilting of the target. The results indicated that it is important to minimize the tilting of the target for robust operation in real-world scenarios.

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Section: Takedownmentioning

confidence: 99%

Design of a Digital Triaxial Force Sensor for Plantar Load Measurements

et al. 2019

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“…In 2015 Du et al [89] used a variation of this method, exploiting the mechanism of eddy current effects to produce an inductive sensor capable of measuring both normal and shear force. As illustrated in Figure 6(a), the sensor consisted of three spiral-wound planar sensing coils, four rubber blocks fixed at the corners of the substrate, and a stainless steel plate.…”

Section: Inductive Sensorsmentioning

confidence: 99%

“…(a) Schematic and prototype of a three-coil inductive force sensor[89]; (b) triaxial soft inductive force sensor[90].…”

mentioning

confidence: 99%

A Review of Wearable Sensor Systems to Monitor Plantar Loading in the Assessment of Diabetic Foot Ulcers

Wang

Jones

Chapman

et al. 2020

IEEE Trans. Biomed. Eng.

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Diabetes is highly prevalent throughout the world and imposes a high economic cost on countries at all income levels. Foot ulceration is one devastating consequence of diabetes, which can lead to amputation and mortality. Clinical assessment of diabetic foot ulcer (DFU) is currently subjective and limited, impeding effective diagnosis, treatment and prevention. Studies have shown that pressure and shear stress at the plantar surface of the foot plays an important role in the development of DFUs. Quantification of these could provide an improved means of assessment of the risk of developing DFUs. However, commerciallyavailable sensing technology can only measure plantar pressures, neglecting shear stresses and thus limiting their clinical utility. Research into new sensor systems which can measure both plantar pressure and shear stresses are thus critical. Our aim in this paper is to provide the reader with an overview of recent advances in plantar pressure and stress sensing and offer insights into future needs in this critical area of healthcare. Firstly, we use current clinical understanding as the basis to define requirements for wearable sensor systems capable of assessing DFU. Secondly, we review the fundamental sensing technologies employed in this field and investigate the capabilities of the resultant wearable systems, including both commercial and research-grade equipment. Finally, we discuss research trends, ongoing challenges and future opportunities for improved sensing technologies to monitor plantar loading in the diabetic foot.

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“…Various sensing mechanisms are exploited, including resistance, capacitance, piezoelectricity, optics and triboelectricity [6,7,8,9,10,11]. Among those, inductive sensors are widely used in the fields of displacement measurements, particle detections, and health monitoring because of their high resolution, long life time, good linearity, high stability, simple structure and immunity to environmental fluctuations [12,13,14,15,16]. According to the law of electromagnetic induction, an inductor can generate a magnetic field as current flows through it.…”

Section: Introductionmentioning

confidence: 99%

A Flexible and Highly Sensitive Inductive Pressure Sensor Array Based on Ferrite Films

Tang

Miao

Chen

et al. 2019

Sensors

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There is a rapid growing demand for highly sensitive, easy adaptive and low-cost pressure sensing solutions in the fields of health monitoring, wearable electronics and home care. Here, we report a novel flexible inductive pressure sensor array with ultrahigh sensitivity and a simple construction, for large-area contact pressure measurements. In general, the device consists of three layers: a planar spiral inductor layer and ferrite film units attached on a polyethylene terephthalate (PET) membrane, which are separated by an array of elastic pillars. Importantly, by introducing the ferrite film with an excellent magnetic permeability, the effective permeability around the inductor is greatly influenced by the separation distance between the inductor and the ferrite film. As a result, the value of the inductance changes largely as the separation distance varies as an external load applies. Our device has achieved an ultrahigh sensitivity of 1.60 kPa−1 with a resolution of 13.61 Pa in the pressure range of 0–0.18 kPa, which is comparable to the current state-of-the-art flexible pressure sensors. More remarkably, our device shows an outstanding stability when exposed to environmental interferences, e.g., electrical noises from skin surfaces (within 0.08% variations) and a constant pressure load for more than 32 h (within 0.3% variations). In addition, the device exhibits a fast response time of 111 ms and a good repeatability under cyclic pressures varying from 38.45 to 177.82 Pa. To demonstrate its practical usage, we have successfully developed a 4 × 4 inductive pressure sensor array into a wearable keyboard for a smart electronic calendar application.

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An Inductive Sensor for Real-Time Measurement of Plantar Normal and Shear Forces Distribution

Abstract: Real-time monitoring of the normal force and shear forces on diabetes patient's foot can provide useful information for physicians and diabetes patients to take actions in preventing foot ulceration.

Cited by 33 publications

References 21 publications

Design of a Digital Triaxial Force Sensor for Plantar Load Measurements

Design of a Digital Triaxial Force Sensor for Plantar Load Measurements

A Review of Wearable Sensor Systems to Monitor Plantar Loading in the Assessment of Diabetic Foot Ulcers

A Flexible and Highly Sensitive Inductive Pressure Sensor Array Based on Ferrite Films

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