This work presents the design, fabrication, and characterization of a printed radio frequency identification tag in the ultra-high frequency band with multiple sensing capabilities. This passive tag is directly screen printed on a cardboard box with the aim of monitoring the packaging conditions during the different stages of the supply chain. This tag includes a commercial force sensor and a printed opening detector. Hence, the force applied to the package can be measured as well as the opening of the box can be detected. The architecture presented is a passive single-chip RFID tag. An electronic switch has been implemented to be able to measure both sensor magnitudes in the same access without including a microcontroller or battery. Moreover, the chip used here integrates a temperature sensor and, therefore, this tag provides three different parameters in every reading.

This paper illustrates the application of the discrete wavelet transform (DWT) for wandering and noise suppression in electrocardiographic (ECG) signals. A novel one-step implementation is presented, which allows improving the overall denoising process. In addition an exhaustive study is carried out, defining threshold limits and thresholding rules for optimal wavelet denoising using this presented technique. The system has been tested using synthetic ECG signals, which allow accurately measuring the effect of the proposed processing. Moreover, results from real abdominal ECG signals acquired from pregnant women are presented in order to validate the presented approach.

The purpose of this study was to validate a new instrumented insole called ECnsole for measuring flight time during vertical jump performance. 66 participants performed 3 different jump tests (squat jump, countermovement jump and Abalakov jump) twice with flight times determined using an instrumented insole composed of 4 pressure sensors (PreECnsole) and an accelerometer sensor (AccECnsole), a laser platform (Sport Jump System Pro), and a high-speed motion capture system (HSC); the latter 2 systems are considered as reference methods. One-way analysis of variance (ANOVA), simple linear regression, and the Bland-Altman method were used to assess validity. Regardless of the jump test performed, the ECnsole system showed a systematic bias close to 0 and a low random error (average random error: ?2.8?cm; ?3.1?cm PreECnsole and AccECnsole vs. HSC system respectively and ??2.3?cm; ?2.9?cm PreECnsole and AccECnsole vs. SJS system respectively). The associations between PreECnsole and AccECnsole with the HSC were very high (R2=0.967 and 0.958 respectively). Furthermore, the associations between PreECnsole and AccECnsole with the SJS were very high (R2=0.978 and 0.966 respectively) as well. Therefore, the ECnsole system can be considered an alternative method for measuring jump height during vertical jump performance.

This work presents the development of a portable, wireless activity monitoring system for the estimation of biomechanical gait parameters. The system uses a pair of instrumented insoles able to measure pressure from different points of the foot including four commercial piezoresistive pressure sensors and a three-axis accelerometer, all together integrated in the insole to determine foot forces during stance and swing phases. The system includes two kinds of analysis data, one on line with a RF communications to a computer, and another off line reading the data from SD memory card. Our system has been validated and tested in different trials, extracting several features during walking for ten participants by means of the combined information from the two kinds of sensors. With the combined data from the complete set of sensors, we can obtain highly valuable information on foot movement during the non-contact period, such as supination or pronation characteristics or anomalous movement during flight time. From our preliminary results, the variation of the lateral acceleration of the foot seems to be correlated with the amount of supination.

The equilibrium of pregnant women is compromised because the falling risk increases as pregnancy progresses. The trajectories of the centers of pressure are related to equilibrium, gait and posture. The purpose of this work was to investigate the fractal behavior of the trajectories of the center of pressure of both feet in standing and walking pregnant women and how they evolve during pregnancy. By using instrumented insoles (F-Scan ® system working at 40 Hz), the trajectories of the center of pressure of both feet were obtained for 71 women in the three trimesters of their pregnancy. The 'detrended fluctuation analysis', a technique designed to extract the fractal properties of a signal, was used to analyze the fractal behavior of both the x and y components of the measured trajectories. Specifically, the fractal characteristic exponents corresponding to the small and large end regions of the corresponding scaling functions were obtained and compared. No differences were found between the characteristic exponents obtained for x and y components nor from the signals found for left and right feet within the statistical uncertainties. In standing conditions all the exponents obtained remained almost constant, regardless of the elapsed pregnancy time, taking values around 0.5. In walking conditions, the small end exponents did not change with respect to those found in static conditions; on the contrary, the large-end exponents reduced as pregnancy progressed, reaching values of the order of −0.6 in the third trimester. The multi-scaling character of the walking signals could be related to the anteroposterior and medio-lateral displacement observed in previous experiments and that could be on the root of the development of musculoskeletal discomfort and a falling risk that increases with the pregnancy time.

No abstract

Low back pain affects around 50% of pregnant women and presents significant morbidity and persistence for years in 20% of postpartum women who report that pain. Numerous studies have documented gait alterations during pregnancy and postpartum. Therefore, an analysis of the relationship between certain gait parameters and low back pain was attempted using low-cost validated instrumented insoles. This work presents a longitudinal cohort study carried out during routine gynecological follow-up visits in the first, second, and third trimesters of pregnancy at an Obstetrics and Gynecology Service. Sample size was 62. Plantar pressure data were collected with specially designed instrumented insoles containing four force sensors to measure peak pressure, center of pressure, and stance phase time in each foot and in each pregnancy trimester. The analysis was carried out on a two-dimensional level, simultaneously considering the data from both feet using Hotelling’s T2 test. This longitudinal study detected relationships between certain gait parameter changes and low back pain during pregnancy. It revealed a cyclic tendency of low back pain prevalence with a maximum in the second trimester and a decrease in the third trimester, which was correlated with alterations of the pregnant gait: excessive foot pronation and rearfoot pressure increase.

An RFID tag with energy harvesting and sensing capabilities is presented in this paper. This RFID tag is based on an integrated circuit (SL900A) that incorporates a sensor front-end interface capable of measuring voltages, currents, resistances, and capacitances. The aim of this work is to improve the communication distance from the reader to the tag using energy harvesting techniques. Once the energy source and harvester are chosen according to the environment of work, the conditioning circuit for energy management has to be appropriately designed with respect to the nature of the transductor. As a proof of concept, a photovoltaic panel is used in this work to collect the energy from the environment that is managed by a DC-DC converter and stored in a capacitor acting as battery. Such energy is used to support the power system of the tag, giving autonomy to the device and allowing data logging. In particular, the developed tag monitors the ambient temperature and the power voltage. It would be possible to add external sensors without changing the architecture. An increase in the read range of more than 200% is demonstrated. This feature is especially interesting in environments where the access could be difficult.