No abstract

No abstract

Strain monitoring allows obtaining critical information regarding the conditions of several systems. It would help, for example, to avoid possible structural damages. However, not all the existing devices are suitable to accomplish this task for a great number of applications, because of the characteristics of measurement environment, which prevent the use of batteries or wired connections. The use of telemetric devices may overcome these limitations, since they rely on the magnetic coupling between two inductors for wireless sensor supply and data transmission. The work treated in this paper presents a technique that permits us to calculate the output of a resistive strain gauge from a measurement of system impedance phase performed at a specific frequency, when distance between the inductors is fixed. We validated the method using a real device working with a low-cost sensor fabricated through inkjet-printing technology on a flexible substrate. We applied successive deformations, until 1% of sensor length at rest position. Calculated strain presents a percentage deviation from measured values going from 0.7% to 7%, whereas the highest uncertainty is 0.02% of sensor length at rest. Experimental results put in evidence, on one hand, the potential of inkjet printing to fabricate valid sensing elements and, on the other hand, that the proposed approach is successful in strain estimation

No abstract

Body motion tracking technologies are widespread in military, medical and sport fields. The work proposes a modular wireless wearable system able to detect hand fingers motion. Such system is composed by a readout unit that analyses the data and by a wearable measuring device directly applied on the tracked finger. This device is equipped with an Inertial Motion Unit (IMU) used to track the first phalanx motion and orientation and with a stretch sensor to monitor the bending angle between the first and second phalanxes. We carried out an experimental study, which is divided in two main parts. In the first one, the transducer performance was evaluated, whereas, in the second part, we tested the capability of the overall system to recognize simple finger movements and different objects grabbed. The preliminary results pave the possibility of developing a modular device, one for each hand finger, able to recognize the grabbed object shape or detect complex gestures.

No abstract

The present work describes a telemetric resistive sensor to be exploited in biomedical applications, in order to monitor vital parameters in real time. The corresponding telemetry technique is based on an impedance measurement performed at its input terminal and on a theoretical study which identifies a complex mathematical relation between sensor's resistance and impedance phase value at a specific frequency point. A model for this system is proposed, analysed and discussed, while the telemetric technique based on it is described

Measuring strain is a task frequently required in many applications and, often, measurement devices have to adopt technologies that respect specific requirements, especially concerning power supply and transmission of information. In particular, the exploitation of wired solutions or batteries has several problems or it should be avoided in harsh environments. A valid answer to these issues is provided by telemetric systems, which consist of a reading unit that communicates with a passive sensor through the magnetic field established between two inductors connected to these components. The present work describes a study carried out on a telemetric system that has some elements of novelty with respect to the major part of those found in the literature. In fact, it operates with a resistive strain gauge realized through the innovative technology of inkjet printing on a flexible substrate. This permits to introduce advantages relating to design variability and low production cost of the components. Experimental tests were conducted in order to characterize the strain gauge and analyze overall system frequency behavior. Preliminary achieved results are satisfying, highlighting the possibility to measure telemetrically the strain from an inkjet-printed resistive sensor