The TexiSense « Smart Sock » - a device for a daily prevention of pressure ulcers in the diabetic foot

International audienceGoals.– The term « diabetic foot » refers to a set of foot pathologies essentially stemming from the neuropathy and arteriopathy of the lower limb associated with diabetes mellitus. Chronic ischemia weakens the healing potential and favors the development of wounds on a more vulnerable foot. Friction or repeated micro-traumas can lead to an ulceration (which in turn can end up in an amputation) that will remain unnoticed because of the somato-sensory deficiency. The current prevention techniques largely relying on visual inspection of the foot and enhancement of the foot/insole interface are not fully satisfying as the prevalence of plantar ulcers remains very high.Patients and methods.– A device for the prevention of plantar ulcers–called “Smart Sock” is described. It consists of:– a sock made of a 100% textile pressure sensing fabric developed by the TexiSense company;– a microcontroller running a biomechanical model of the soft tissues of the foot of the diabetic person;– a vibrating watch (and eventually a smartphone) used to warn the bearer if a pressure pattern threatens the soft tissues integrity.Results.– Internal overpressures within the soft tissues, especially nearby bony prominences are likely to develop into deep foot ulcerations. The biomechanical model gives an estimation of their magnitude based on the external pressures measured by the sock/sensor. This modeling relies on a faithful representation of the morphology of the diabetic subject. The device sends a vibro-tactile alert in case of occasional overpressure or excessive stress dose accumulated during daytime activities.Discussion.– The continuous use of the device, compatible with daytime activities of the diabetic person, helps compensate for the lack of attention in the prevention of pressure ulcer formation. The TexiSense “Smart Sock” can be designed so that when worn, pressure sensors fall onto sensitive anatomical areas such as the dorsal side of the toes or the posterior side of the heel, which makes it also possible to monitor regions located outside the sole of the foot

Influence of the calcaneus shape on the risk of posterior heel ulcer using 3D patient-specific biomechanical modeling.

International audienceMost posterior heel ulcers are the consequence of inactivity and prolonged time lying down on the back. They appear when pressures applied on the heel create high internal strains and the soft tissues are compressed by the calcaneus. It is therefore important to monitor those strains to prevent heel pressure ulcers. Using a biomechanical lower leg model, we propose to estimate the influence of the patient-specific calcaneus shape on the strains within the foot and to determine if the risk of pressure ulceration is related to the variability of this shape. The biomechanical model is discretized using a 3D Finite Element mesh representing the soft tissues, separated into four domains implementing Neo Hookean materials with different elasticities: skin, fat, Achilles' tendon, and muscles. Bones are modelled as rigid bodies attached to the tissues. Simulations show that the shape of the calcaneus has an influence on the formation of pressure ulcers with a mean variation of the maximum strain over 6.0 percentage points over 18 distinct morphologies. Furthermore, the models confirm the influence of the cushion on which the leg is resting: a softer cushion leading to lower strains, it has less chances of creating a pressure ulcer. The methodology used for patient-specific strain estimation could be used for the prevention of heel ulcer when coupled with a pressure sensor

Pressure ulcer prevention in spinal cord injury subjects using the TexiSense pressure sensing textile

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Body numerical phantoms for estimating soft tissue pains or injuries when interacting with shoes, seats and mattresses

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Mutual optical injection in coupled DBR laser pairs

We report an experimental study of nonlinear effects, characteristic of mutual optical coupling, in an ultra-short coupling regime observed in a distributed Bragg reflector laser pair fabricated on the same chip. Optical feedback is amplified via a double pass through a common onchip optical amplifier, which introduces further nonlinear phenomena. Optical coupling has been introduced via back reflection from a cleaveended fibre. The coupling may be varied in strength by varying the distance of the fibre from the output of the chip, without significantly affecting the coupling time. © 2008 Optical. Society of America

Monolithically integrated heterodyne optical phase-lock loop with RF XOR phase detector

We present results for an heterodyne optical phase-lock loop (OPLL), monolithically integrated on InP with external phase detector and loop filter, which phase locks the integrated laser to an external source, for offset frequencies tuneable between 0.6 GHz and 6.1 GHz. The integrated semiconductor laser emits at 1553 nm with 1.1 MHz linewidth, while the external laser has a linewidth less than 150 kHz. To achieve high quality phase locking with lasers of these linewidths, the loop delay has been made less than 1.8 ns. Monolithic integration reduces the optical path delay between the laser and photodiode to less than 20 ps. The electronic part of the OPLL was implemented using a custom-designed feedback circuit with a propagation delay of similar to 1 ns and an open-loop bandwidth greater than 1 GHz. The heterodyne signal between the locked slave laser and master laser has phase noise below. 90 dBc/Hz for frequency offsets greater than 20 kHz and a phase error variance in 10 GHz bandwidth of 0.04 rad(2). (C) 2011 Optical Society of Americ

Millimeter-Wave Photonic Components for Broadband Wireless Systems

We report on advanced millimeter-wave (mm-wave) photonic components for broadband radio transmission. We have developed self-pulsating 60-GHz range quantum-dash Fabry-Perot mode-locked laser diodes (MLLD) for passive, i.e., unlocked, photonic mm-wave generation with comparably low-phase noise level of -76 dBc/Hz @ 100-kHz offset from a 58.8-GHz carrier. We further report on high-frequency 1.55-mu m waveguide photodiodes (PD) with partially p-doped absorber for broadband operation (f(3dB) similar to 70-110 GHz) and peak output power levels up to +4.5 dBm @ 110 GHz as well as wideband antenna integrated photomixers for operation within 30-300 GHz and peak output power levels of -11 dBm @ 100 GHz and 6-mA photocurrent. We further present compact 60-GHz wireless transmitter and receiver modules for wireless transmission of uncompressed 1080p (2.97 Gb/s) HDTV signals utilizing the developed MLLD and mm-wave PD. Error-free (BER = 10(-9), 2(31) - 1 PRBS, NRZ) outdoor wireless transmission of 3 Gb/s over 25 m is demonstrated, as well as wireless transmission of uncompressed HDTV signals in the 60-GHz band. Finally, an advanced 60-GHz photonic wireless system offering record data throughputs and spectral efficiencies is presented. For the first time, we demonstrate photonic wireless transmission of data throughputs up to 27.04 Gb/s (EVM 17.6%) using a 16-QAM OFDM modulation format resulting in a spectral efficiency as high as 3.86 b/s/Hz. Wireless experiments were carried out within the regulated 57-64-GHz band in a lab environment with a maximum transmit power of -1 dBm and 23 dBi gain antennas for a wireless span of 2.5 m. This span can be extended to some 100 m when using high-gain antennas and higher transmit power levels

The Bank of Standardized Stimuli (BOSS), a New Set of 480 Normative Photos of Objects to Be Used as Visual Stimuli in Cognitive Research

There are currently stimuli with published norms available to study several psychological aspects of language and visual cognitions. Norms represent valuable information that can be used as experimental variables or systematically controlled to limit their potential influence on another experimental manipulation. The present work proposes 480 photo stimuli that have been normalized for name, category, familiarity, visual complexity, object agreement, viewpoint agreement, and manipulability. Stimuli are also available in grayscale, blurred, scrambled, and line-drawn version. This set of objects, the Bank Of Standardized Stimuli (BOSS), was created specifically to meet the needs of scientists in cognition, vision and psycholinguistics who work with photo stimuli