As an alternative to conventional batteries and other energy scavenging techniques, this paper introduces the idea of using micro-turbines to extract energy from wind forces at the microscale level and to supply power to battery-less microsystems. Fundamental research efforts on the design, fabrication, and test of micro-turbines with blade lengths of just 160 µm are presented in this paper along with analytical models and preliminary experimental results. The proof-of-concept prototypes presented herein were fabricated using a standard polysilicon surface micro-machining silicon technology (PolyMUMPs) and could effectively transform the kinetic energy of the available wind into a torque that might drive an electric generator or directly power supply a micro-mechanical system. Since conventional batteries do not scale-down well to the microscale, wind micro-turbines have the potential for becoming a practical alternative power source for microsystems, as well as for extending the operating range of devices running on batteries.

In this paper, a novel microgripper based on two perpendicular arrangements of beams and a chevron actuator is shown. In each perpendicular arrangement, the constrained displacement of the double clamped beams, joined at their endpoint, produces a buckling in each beam, which favors the displacement of each arm of the microgripper, normally open. These arrangements constitute the highly flexible structures of the microgripper. Their buckling is produced by the force applied by chevron arrow, producing a reaction force in the range of 174.44 μN in the microgripper jaws. Chevron actuator is fed by a thermal source. Temperature in microgripper tips is of 34.42°C and the operation frequency is 33.966 kHz, at maximum load thermal applied of 200°C. The mechanical, thermal and modal analyses of this integrated structure was supported by SIMSOLID TM , based on Finite Element Analysis. The simulation was developed with Polysilicon as structural material.

Agriculture represents the main source of food in the world, but it also represents challenges such as population growth, urbanization and aging, global economic growth, investment, trade, and food prices and competition for natural resources. The development of technology can help us cope with these challenges. The internet of things (IoT) technology represents the future of computing and communications. These can be useful to improve traditional agriculture methods around the world. By implementing these modern technologies is possible to reduce costs and maintenance and, to increase the performance of our agriculture processes and goods. Particularly, one of this relatively new technology is the LoRa communication protocol that uses long wavelengths for the communication link to obtain long ranges. This is extremely useful in agriculture where the communicating areas are extensive crop fields and greenhouses. This paper proposes and presents the development of a mobile LoRaWAN gateway device that can be applied to increase greenhouses' productivity and accuracy. The presented development includes the use of a Heltec's Mini LoRa Gateway controlled by a Raspberry Pi 3 B+. It is powered by an external Li-On battery and uses a defined number of LoRa nodes with sensors. Sensors will measure humidity and temperature and send the data, which are gathered by the mobile LoRaWAN gateway. These data are processed using third-party free online services. This document illustrates and explains the development and application of data collectors for agriculture and their advantages.

Real-time haptic interactions occur under two exploration modes: active and passive. In this paper, we present a series of experiments that evaluate the main perceptual characteristics of both exploration modes. In particular, we focus on haptic shape recognition as it represents a fundamental task in many applications using haptic environments. The results of four experiments conducted with a group of 10 voluntary subjects show that the differences in motor activity between active and passive haptics ease the perception of surfaces for the first case and the perception of pathways for the latter. In addition, the guidance nature of passive haptics makes the pathway direction easy to recognize. This work shows that this last observation could find application in more challenging tasks such as navigation in space.

The electrical output of a photovoltaic system is often related to the plane-of-array global irradiance and the cell operating temperature. However, the spectral distribution of the irradiance also influences the system electrical behaviour, through its coupling with the spectral response of the photovoltaic material employed. Many authors have evaluated the spectral performance of different types of semiconductors under real operating conditions worldwide by using different methods and spectral indexes. However, there are not comparative studies on the accuracy of these methods in the literature. In this paper, two simplified existing indexes and a novel introduced index are compared to the spectral factor method in order to assess their relative accuracy for the climate of Granada, Southern Spain, and considering the most widespread used photovoltaic materials. Results show the election of a suitable index depends on the type of material, availability of spectral response information of the material, computing capabilities and required accuracy. The maximum annual relative error with respect to the spectral factor considering every index and material is 1.77%, while the maximum monthly relative error can reach 4.22%. (C) 2018 Elsevier Ltd. All rights reserved.

This article presents the design and implementation of a microgripper device actuated by a piezoelectric stack. In order to reduce fabrication costs, conventional piezoelectric buzzers are used that are easily found in the market at very low cost. Polylactic Acid (PLA) was chosen as the structural material for the design of the mechanisms of the microgripper, the choice of this material considerably reduces the total implementation cost. The originality of this work resides in the material used and in the stacked piezoelectric actuator. The main contribution is the demonstration of a design methodology that implements prototype compliance mechanisms at millimeter scale for validation purposes before proceeding to the fabrication in micrometric scale. Even so, the system in mm scale can also be used for micromanipulation due to the range of its microgripper jaws' aperture and its reliability. ANSYS™ was used as the software tool for simulation.

This paper presents the design, development, and preliminary evaluation of a computer-based system capable of simulating the consequences of several eye diseases in human vision. The system consists of a video camera, a computer, and a virtual reality (VR) helmet. Real-time image processing techniques are applied to the camera's video signal and the result is projected on the VR helmet. Upon the use of filters or masks, users can experience eye pathologies such as diabetic retinopathy, macular degeneration, hemianopsia, retinitis pigmentosa, among others. The system was evaluated by normally sighted in tasks such as reading and mobility. Results obtained allowed users to develop a greater awareness of the nature of visual impairments. The system is also intended to be used as a technological platform for testing assistive devices for visually impaired people.

This paper presents the design, development, and preliminary evaluation of a computer-based system capable of simulating the consequences of several eye diseases in human vision. The system consists of a video camera, a computer, and a virtual reality (VR) helmet. Real-time image processing techniques are applied to the camera's video signal and the result is projected on the VR helmet. Upon the use of filters or masks, users can experience eye pathologies such as glaucoma, hemianopsia, macular degeneration, retinitis pigmentosa, among others. The system was validated by qualified experts and evaluated by healthy sighted in tasks such as reading and mobility. Results obtained allowed users to develop a greater awareness of the nature of visual impairments. The system is also intended to be used as a technological platform for testing assistive devices for visually impaired people.

This article presents a 3rd Order 1-bit ΔΣ modulator optimized for applications requiring high effective resolution and linearity within the 20-kHz band. Furthermore, this work also describes architectural approaches for designing modulators with different order, oversampling rate, and number of quantization bits. Such approaches can be leveraged in a variety of applications in digital signal processing for data communications, filters, motor controllers, data acquisition, high-fidelity audio, DACs, and others operating in baseband. The 3rd Order modulator was implemented in standard 180nm CMOS; experimental measurements show a SNDR=126dB equivalent to 20-bits of effective resolution with a total harmonic distortion THD=0.03%. The circuit is able to operate in low-voltage conditions from 0.55 to 1.8 Volts.

Resumen es: Como una alternativa a los microactuadores termicos accionados electricamente, este trabajo presenta un microdispositivo que puede operar aprovechando el...

Este trabajo se centra en el desarrollo de una antena de parche diseñada para Sistemas de Posicionamiento Global (GPS), con la finalidad de emplearla como antena de reemplazo en aplicaciones automotrices. En las simulaciones y pruebas se pone énfasis en su ganancia. Las pruebas de transmisión-recepción se realizaron para verificar que la frecuencia de operación de la antena fabricada sea la adecuada. Las pruebas con un kit de GPS comercial fueron realizadas para comparar su desempeño como antena de reemplazo. Las pruebas de laboratorio muestran que se cumple con el mínimo requerido para cubrir ambas frecuencias, de recepción y de transmisión, mientras que las pruebas del prototipo, en el techo vehículo sin movimiento, mostraron ligeras variaciones en los datos de posición, comparados con los obtenidos con el kit con su antena original. Las pruebas de viaje mostraron la suficiente precisión en la determinación de la posición para su uso.

The NiTiNOL diaphragm, under two geometries, were simulated on a Silicon wafer and controlled by an external heat source. As the substrate bottom wall heats and conducts heat, the thermal expansion raises the thin layer which can be used as an actuator. The case of heat source applied on the top walls was also considered. The simulations were realized by means of the mechanical and thermal properties of materials. A comparison among the performance of the diaphragm based on the geometries with a plane layer, a layer with a primary boss, and finally with primary and secondary bosses is presented. Each process was simulated in COMSOL Multiphysics. The distribution of deformation using bosses is similar to the analyzed cases using pressure instead of heat. The maximum obtained displacement for NiTiNOL is of approximately 2.5 micrometers at 343°K, at the same conditions, Silicon case reaches 0.9 μm. The diaphragm behavior is also compared with the cases of Silicon and Cu-Al-Ni. Our interest in the development of MEM actuators only controlled by external heat sources is due to several reasons. At first, because these clean energy sources sometimes reaches high density values, but they have not been well-spent. The most of MEMS thermal actuators need a current flow to heat the MEM device, by means of the Joule effect, and produce the corresponding thermal expansion. In this paper, the displacement depends on the external source, in accordance with the mechanical and electrical properties of the used materials.

This paper presents a novel wearable interface for the foot: a shoe-integrated tactile display that enables users to obtain information through the sense of touch via their feet. A 16-point array of actuators stimulates the sole of the foot by inducing different vibration frequencies. A series of experiments were conducted with 20 sighted and 5 blind voluntary subjects to evaluate the role of tactile perception by the human foot and the tactile sensitivity of the plantar surface. Tests evaluated the perception of simple shapes, patterns and directional instructions. The results showed that some information is discriminable and that tactile-foot stimulation could be used for a wide number of applications in human-machine interaction. Furthermore, the results also suggested that the blind perform better in some key tasks and support the feasibility of footwear providing tactile feedback for situational awareness, mobility and the navigation assistance of the blind.

The meter device presented in this work consists of a photo-detector mounted on the mechanism of a mobile rectangular arc. One stepper motor located on the lateral axis of the device displaces the sensor along a semi-circular trajectory of 170 degrees, almost half meridians. Another motor located at the base of the device enables 360 degrees rotation of the illumination source under test. This arrangement effectively produces a semi-spherical volume for the sensor to move within. The number of measurement points is determined by programming the two stepper motors. Also, the use of a single photo-sensor ensures uniformity in the measurements.The mechanical structure provides enough rigidity for supporting the accuracy required by the data acquisition circuitry based on a DSPIC. Measurement of illumination sources of different sizes is possible by using adjustable lengths of the mobile base and the ring for a maximum lamp length of 0.16 m. Because this work is partially supported by a private entity interested in the characterization of its products, especial attention has been given to the luminaries based on LED technology with divergent beams. The received power by the detector is useful to obtain the irradiance profile of the lighting source under test. The meter device presented herein is a low-cost prototype designed and fabricated using recyclable materials only such as "electronic waste".

In this semi-spherical meter, a single detector is used to realize all measurements, which is located on the extreme of a rectangular ring (assumed as joined two mobile branches in order to compensate the weights), describing half-meridians from 0° up to 170°. The illumination source under test is located at the center of the mobile support, which can rotate 360° horizontally. The two combined movements allow us to obtain a semi-spherical geometry. The number of measurement points is determined by the two step-motors located under the mobile support of the luminary and on one of the two fixed arms, which support the mobile rectangular ring, respectively. The mechanical arrangement has the enough rigidity to support the precision required for the acquisition stage, based on a dsPIC. The main advantages of this arrange are: Its low costs (using recyclable materials only such as "electronic waste"), a reliable detection based on a single photo-detector, with an integrated amplification stage, and the mechanical design. The received power by the detector is useful to obtain the irradiance profile of the lighting sources under test. The semi-spherical geometry of the meter makes it useful for the analysis of directive and non directive sources, in accordance with the angle described by the mobile ring. In this work, special attention is given to LED lamps due to its impact in several sceneries of the daily life. A comparison between the irradiance patterns of two LED lamps is also given.

Antenna characteristics are chosen according to the features determined by the systems where they will be used. While some systems require a very narrow bandwidth, others may operate with a much wider bandwidth. Some techniques used for increasing the bandwidth of a given antenna have considered mechanical adjustment of the air layer thickness, with the consequent change on the effective permittivity and performance. Some other systems consider a suitable choice of feeding techniques and impedance matching network. However, approaches for reducing the bandwidth have not received the same level of attention. Narrow bandwidth antennas are of particular interest in security and surveillance systems. In this work we present a technique, based on the design of a pentagonal antenna array, which allows for adjusting the bandwidth in either direction. The array is formed by an inner patch designed at the desired operating frequency of the system and a gap coupled external ring centered at a different frequency (lower or very near the operating frequency), which determines the potential bandwidth increment or decrement. The feed point is located on the inner patch. As a proof-of-concept, this work offers a tuning range that goes from -40% of the center frequency up to +50% of the center operating frequency of the patch antenna. The single patch antenna of this work was designed and simulated at an operating frequency of 4.9 GHz on RT/Duroid 5880.

We describe the design and experimental characterization of two optimized thermal actuators devised to operate by means of scavenging heat from the environment. Different from the traditional MEMS thermal actuator that relies on electric current to generate heat by Joule effect, the devices presented here are optimized to absorb external heat and convert it into mechanical displacement and force. The behavior of vertical and horizontal microactuators fabricated in a standard surface micromachining process (PolyMUMPs, Research Triangle Park, North Carolina) demonstrates the viability of exploiting heat from the surrounding medium to realize batteryless microsystems. Analytical and finite element models are provided in support of the design. Results show that fairly large and useful displacements can be achieved at commonly available operating temperatures. (c) 2009 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3152001]

This paper reports on the first investigation to design, build and characterize a dual vertical and horizontal microactuator based on the topology of a thermal chevron actuator. The chevron-based vertical actuator displays superior performance in comparison to existing electrostatic and electrothermal vertical actuators. The device has the capacity to produce linear vertical motion without deformation of the upper beam surface and is well suited for a variety of optical and microassembling applications. A methodology that may extend the capabilities of standard surface micromachining MEMS technology to design three-dimensional structures is also presented.

This paper presents the design, implementation and experimental platform of a low-cost intelligent wheelchair for the motor-disabled. The first prototype developed is an electric power wheelchair which cost is one third of the commercially available ones and is capable of both manual and autonomous operation. Manual operation relies on a joystick and is intended for people that, in spite of their disability, are well capable of maneuvering the wheelchair. Autonomous operation relies on a mobile robotics inspired computer vision system to navigate through corridors, halls, indoors/outdoors, among other structured environments and is indented for the severely impaired, such as the tetraplegics. Besides from being an affordable-to-everyone device, its current application is museum guidance: based on a location-aware interactive storytelling platform, the wheelchair guides the user among the museum's rooms while providing audio information.