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Guimarães, Portugal

Da Silva A.F.,University of Minho | Goncalves A.F.,TMG Automotive | Mendes P.M.,University of Minho | Correia J.H.,University of Minho
IEEE Sensors Journal

A wearable sensing glove for monitoring hand gestures and posture has been developed. The glove sensing capability is based on optical fiber Bragg gratings (FBGs) sensors. These sensors, due to their inherent self-referencing and multiplexing capability, are a value-added choice for this application. A single optical fiber would cross all the hand with Bragg structures in specific spots, as the finger joints. The functionality and performance of the glove was fully evaluated. The sensor response was linear to the hand movements for opening and closing down. Through the sensor response, it was possible to retrieve information about the joint angles from which other set of information like finger force can be estimated. The developed glove was able to provide numerical data about the angles of the hand posture in real time. The simplicity of the system and performance makes it well suitable for physical therapy applications, study of the human kinematics during sport activity, virtual reality or even remote control applications, among others. © 2006 IEEE. Source

Da Silva A.F.,University of Minho | Goncalves A.F.,TMG Automotive | De Almeida Ferreira L.S.A.,INESC Porto | Araujo F.M.M.,INESC Porto | And 2 more authors.
IEEE Sensors Journal

Monitoring systems can already be found in common applications, from automotive to aeronautics or biomedical. However, the application of these monitoring systems has not yet been a very easy task, especially, at the sensor application step. A smart structure with sensing capabilities would allow to overcome the existing issues in the installation of sensor networks. As the size of this type of systems and the market requirements are significant, an industrial manufacturing process needed to be considered. An integrated solution based in Fiber Bragg Grating sensors embedded in PVC laminates was manufactured by industrial spread-coating process. The resultant structure is a temperature and strain sensitive foil that was characterized in terms of surface structure, optical response and overall performance. The integrated solution behavior had a slope of 0.8 pm by microstrain with a measurement range of 1.2 mm when the fiber was straight in the foil. Different fiber layouts were also tested and defined the minimum curve radius in 10 mm. The foil also presented a dimensional stability above 99%, ensuring the capability to sustain molding process. A mechanical analysis to evaluate the elongation capabilities and optical response was conducted. Three samples with different sensor positioning were subjected to the test. In the end, a sample, with the sensor in a 45° angle regarding the displacement axis, achieved the best compromise between maximum elongation range (25%) and optical response linearity. For the temperature response, a wavelength deviation of 1.7 nm was obtained for a 100°C temperature change. © 2010 IEEE. Source

Silva A.F.,University of Minho | Goncalves F.,TMG Automotive | Ferreira L.A.,FiberSensing | Ferreira L.A.,INESC Porto | And 4 more authors.
Proceedings of SPIE - The International Society for Optical Engineering

Optical fiber sensors are increasingly used for monitoring purposes, but flexible smart structures based in this type of technology have many industrial applications. This paper explores a new approach for integrating optical fiber sensors in flexible substrates that can be mounted in host structures to monitor. This approach combines two well establish components, Fiber Bragg grating (FBG) sensors and flexible skin-foils. A three-layer foil construction based on the spread-coating process was defined, in which the fiber was embedded in the middle layer. Such disposition ensured protection to the optical fiber element without reducing the sensitivity to external stimulus. The functional prototypes were subject to thermal and mechanical tests, in which its performance was evaluated. The smart structure behaves linearly to temperature cycles by 0.01 nm/°C and is able to withstand high strain cycles without affecting the measurement characteristics. The obtained results validated this approach. In addition, the flexibility of the explored method allows custom fiber layouts, finishing patterns and colors, enabling this way a range of possible application fields. © 2010 SPIE. Source

Silva A.F.,University of Minho | Goncalves F.,TMG Automotive | Ferreira L.A.,FiberSensing | Ferreira L.A.,INESC Porto | And 4 more authors.
Materials Science Forum

Optical sensors have hit their maturity and a new kind of systems is being developed. This paper deals with the development of a new sensing structure based on polymeric foils and optic fiber sensors, namely the Fiber Bragg Grating sensors. Sensor integration in polymeric foils, using industrial process is the proposed goal. To achieve this goal, Finite Element Analysis was used for prototype modeling and simulation. The model was subjected to loads and restraints in order to retrieve information about stress distribution and displacement of specific points. From the simulation was possible to predict the sections where the sensor should be positioned. A prototype was then fabricated using industrial processes. Tests indicate that the polymeric foil influence on the sensor performance may exist. However, the prototype was able of transferring the full deformation to the optical sensor. Moreover, the optical sensor, which is incorporated in the polymeric foil, is fully functional with high sensitivity, 0.6 picometer by microstrain, allowing deformation measurements, up to 1.2 millimeter. © (2010) Trans Tech Publications. Source

Ferreira da Silva A.,University of Minho | Goncalves F.,TMG Automotive | Mateus Mendes P.,University of Minho | Higino Correia J.,University of Minho
Polymers for Advanced Technologies

The development of smart solutions based on optical fiber technology for any kind of structure such as buildings, aircrafts, or even for human body kinematics, is becoming more and more common. The ability to provide coverings for different structures that can enable monitoring functions beside the esthetic purpose of the covering is an important add-value characteristic. Nevertheless, an open issue is to find an effective solution for the fabrication and application procedure, preferably that scales at a production level. This article explores the insertion of optical fibers into polymeric PVC foils based on the spread-coating fabrication process. The success of this integration approach allows the use of photonic technology in different fields with minor application issues. The material choice for the substrate is a crucial step when choosing integrated solution. Three PVC paste formulations were explored in order to guarantee the optimal integration of optical fiber. A high-viscosity and not monolithic paste formulation emerged as the best choice. This formulation provided the best adhesion, reducing in great scale the surface undulation and paste displacement that the optical fiber tends to do and, its 362% stretch capability is sufficient for special applications, as strain sensitive one. © 2010 John Wiley & Sons, Ltd. Source

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