A proximity sensor for the measurement of the inter-foot distance in static and dynamic tasks

Measuring the base of support is of paramount importance in determining human stability during gait or balance tests. While wearable inertial sensors have been successfully employed to quantify numerous gait parameters (velocity, stride length, etc), they could not be used to estimate quantities related to the feet relative position. Thus, alternative technological solutions need to be investigated. Some attempts have been made by combining light intensity infrared or ultrasounds sensors with inertial measurement units. Lately, the Infrared Time-of-Flight technology (IR-ToF) has become popular for measuring distances. IR-ToF sensor measures the time an electromagnetic wave needs to travel a distance. The aim of this work was to investigate the feasibility of the use of an IR-ToF sensor for estimating the inter-foot distance (IFD) in both static and dynamic tasks. Very accurate IFD estimates were obtained during Static (MAE%=3.3%) and Oscillation (MAE%=4.1%) conditions, while larger errors during Gait trials (MAE%=19.8%)

Static and dynamic accuracy of an innovative miniaturized wearable platform for short range distance measurements for human movement applications

Magneto-inertial measurement units (MIMU) are a suitable solution to assess human motor performance both indoors and outdoors. However, relevant quantities such as step width and base of support, which play an important role in gait stability, cannot be directly measured using MIMU alone. To overcome this limitation, we developed a wearable platform specifically designed for human movement analysis applications, which integrates a MIMU and an Infrared Time-of-Flight proximity sensor (IR-ToF), allowing for the estimate of inter-object distance. We proposed a thorough testing protocol for evaluating the IR-ToF sensor performances under experimental conditions resembling those encountered during gait. In particular, we tested the sensor performance for different (i) target colors; (ii) sensor-target distances (up to 200 mm) and (iii) sensor-target angles of incidence (AoI) (up to 60°). Both static and dynamic conditions were analyzed. A pendulum, simulating the oscillation of a human leg, was used to generate highly repeatable oscillations with a maximum angular velocity of 6 rad/s. Results showed that the IR-ToF proximity sensor was not sensitive to variations of both distance and target color (except for black). Conversely, a relationship between error magnitude and AoI values was found. For AoI equal to 0°, the IR-ToF sensor performed equally well both in static and dynamic acquisitions with a distance mean absolute error <1.5 mm. Errors increased up to 3.6 mm (static) and 11.9 mm (dynamic) for AoI equal to ±30°, and up to 7.8 mm (static) and 25.6 mm (dynamic) for AoI equal to ±60°. In addition, the wearable platform was used during a preliminary experiment for the estimation of the inter-foot distance on a single healthy subject while walking. In conclusion, the combination of magneto-inertial unit and IR-ToF technology represents a valuable alternative solution in terms of accuracy, sampling frequency, dimension and power consumption, compared to existing technologies

A histological study of eosinophilic granuloma in mice following infestation with Anisakis larvae

Anisakidosis is a parasitic anthropozoonosis caused by the nematode larvae of the Anisakidae family. Anisakid nematodes belonging to the Anisakis pegreffii are highly prevalent in several fish species living in the Mediterranean sea. The larvae can accidentally infect humans following the ingestion of infected raw or undercooked sea fish. A migrating larva causes a clinical disease when it invades the stomach or intestinal wall and peritoneum, mimicking an eosinophilic gastroenteritis or an ulcer. In this preliminary experiment, the histopathology of the newly-formed parasitic granulomas in mice infested with third stage Anisakis pegreffii larvae, was studied and described. The larvae were morphologically identified as Anisakis type I by the presence of a boring tooth and a mucron, without ventriculus and caecum. The larval DNA was extracted and amplified by polymerase chain reaction (PCR). After PCR, the samples were processed to undergo restriction fragment length polymorphism analysis (RFLP). This was done to scan the restriction profiles for genetic identification. PCR products were purified and sequenced. The sequences were analysed to detect the relationship between nucleotides and perform a phylogenetic analysis. The paraffin-embedded granuloma samples showed worms having a diameter of 0.55 mm x 0.37 mm, polymyarian muscle cells and a circular intestine. The histological profiles showed a primary lesion at the site of anisakid penetration marked by oedema and neutrophil and eosinophil infiltration. The presence of histiocytes or epithelioid histiocytes, lymphocytes, monocytes, and plasma cells was also possible. Fibrinous exudation, hemorrhage, or vascular damage were detected within the first week of the acute intestine infection with a massive eosinophilic infiltration. Two weeks after the infestation, the infiltrating host cells formed a granuloma in the tissue surrounding the penetrated worm mainly consisting of eosinophils, a large number of fibroblasts and a varying number of admixed multinucleated giant cells. In order to explain the origin of the eosinophilic granulomas, a study into the produced substance attracting eosinophils and other host white blood cells to the area will carry out

Miniaturized Blood Pressure Telemetry System with RFID Interface

This work deals with the development and characterization of a potentially implantable blood pressure telemetry system, based on an active Radio-Frequency IDentification (RFID) tag, International Organization for Standardization (ISO) 15693 compliant. This approach aims to continuously measure the average, systolic and diastolic blood pressure of the small/medium animals. The measured pressure wave undergoes embedded processing and results are stored onboard in a non-volatile memory, providing the data under interrogation by an external RFID reader. In order to extend battery lifetime, RFID energy harvesting has been investigated. The paper presents the experimental characterization in a laboratory and preliminary in-vivo tests. The device is a prototype mainly intended, in a future engineered version, for monitoring freely moving test animals for pharmaceutical research and drug safety assessment purposes, but it could have multiple uses in environmental and industrial applications

A Time-of-Flight Based Energy Measurement System for the LIGHT Medical Accelerator

The LIGHT proton therapy facility is the first compact Linac that will deliver proton beams up to 230 MeV for cancer treatment. The proton beam is pulsed; pulses repetition rate can reach 200 Hz. LIGHT prototype is currently being commissioned by AVO/ADAM at CERN, while the first full installation is foreseen in 2019. Beam energy translates directly to range penetration in the body, so it is of the utmost importance to monitor it accurately especially for Linacs, since each beam pulse is directly transported to the patient. We present the implementation of a non-interceptive beam energy measurement system based on the Time-of-Flight technique. Unlike state of the art ToF systems this one has been designed to measure autonomously the mean energy of the beam with medical resolution (0.03 %) by processing as little as 1 us of data providing the result within 1 to 2 ms over an energy range from 5 to 230 MeV. The first results for beams up to 7.5 MeV are shown

Miniaturized Blood Pressure Telemetry System with RFID Interface

This work deals with the development and characterization of a potentially implantable blood pressure telemetry system, based on an active Radio-Frequency IDentification (RFID) tag, International Organization for Standardization (ISO) 15693 compliant. This approach aims to continuously measure the average, systolic and diastolic blood pressure of the small/medium animals. The measured pressure wave undergoes embedded processing and results are stored onboard in a non-volatile memory, providing the data under interrogation by an external RFID reader. In order to extend battery lifetime, RFID energy harvesting has been investigated. The paper presents the experimental characterization in a laboratory and preliminary in-vivo tests. The device is a prototype mainly intended, in a future engineered version, for monitoring freely moving test animals for pharmaceutical research and drug safety assessment purposes, but it could have multiple uses in environmental and industrial applications

Measurement of the inter-foot distance using a Time-of-Flight proximity sensor: preliminary evaluation during leg oscillation exercises

The distance between the feet during walking could be a key factor to better understand gait stability. The aim of this work was to investigate the application of an Infrared Timeof-Flight sensor in the inter-foot distance estimation during leg oscillation exercises. The results, compared to a stereophotogrammetric system used as gold standard, showed a mean absolute error between 3.6 mm and 6.9 mm and a mean absolute percentage error in the range of 1.9% to 3.8%. An improvement of 50% (6 mm) in the inter-foot distance accuracy, compared to a wearable platform based on ultrasound and inertial sensors, was observed

Indoor distance estimated from Bluetooth Low Energy signal strength: Comparison of regression models

Bluetooth Low Energy (BLE) is a wireless technology for exchanging data, over short distances, designed for the Internet-of-Things era. As widely supported by wearable devices, BLE has the potential to become an alternative for indoor-localization and proximity sensing. The aim of this work was to perform a thorough characterization of the RSSI-distance relationship under controlled conditions using two BLE devices. Four calibration models underwent to a comparative evaluation analysis. The best results were obtained using a polynomial model with a mean distance percentage error equal to 25.7% (0.4 m) in the range 0-3 m. An overall improvement of 14.3% (0.24 m) in the distance estimate compared to the exponential model commonly adopted in the literature was reported