Design and simulation of a novel pressure microgripper based on Microelectromechanical, MEM technology, and composed by several electrothermal microactuators were carried out in order to increment the displacement and the cutoff force. The implementation of an element of press or gripping in the arrow of chevron actuator was implemented to supply stability in the manipulation of micro-objects. Each device of the microgripper and its fundamental equations will be described. The fundamental parameters to understand the operation and behaviour of the device are analyzed through sweeps of temperature (from 30 °C up to 100 °C) and voltage (from 0.25 V up to 5 V), showing the feasibility to operate the microgripper with electrical or thermal feeding. The design and simulation were development with Finite Element Method (FEM) in Ansys-Workbench 16.0. In this work, the fundamental parameters were calculated in Ansys-Workbench. It is shown, that structural modifications have great impact in the displacement and the cut-off force of the microgripper.
Due to the diversity and multiple energy domains involved, Micro-Electromechanical Systems MEMS devices are vulnerable to several mechanical failures such as fatigue. They been widely used in military applications, radio frequency systems, pressure sensors, automotive industry, among several others. Most MEMS devices contain moving parts that are subjected to cyclic loading, which degrade the device´s efficiency. Due to the high importance of MEMS in various applications, it is necessary to know their lifetime to prevent any damage or process discontinuity to which the system is subject. There have been several investigations in particular on the fatigue analysis in presence of cracks, however in terms of lifetime under cycling load, information is not abundant. The fatigue analysis can be performed for characterizing the ability of materials to support many cycles. Some parts of systems are exposed to strong stress level experiences during its usable lifetime, so the analysis must be focused on them. In this paper, a simulated fatigue analysis of classic, Z-shape and optimized chevron with Z shape arms is shown. Simulations are made using Ansys 15.0, to obtain the arms lifetime of the system because they are subjected to greater stresses in the presence of cyclic loading.
For illumination sources designers is important to know the illumination distribution of their products. They can use several viewers of IES files (standard file format determined by Illuminating Engineering Society). This files are necessary not only know the distribution of illumination, but also to plain the construction of buildings by means of specialized softwares, such as Autodesk Revit. In this paper, a complete portable system for luminaries’ characterization is given. The components of the systems are: Irradiance profile meter, which can generate photometry of luminaries of small sizes which covers indoor illumination requirements and luminaries for general areas. One of the meter´s attributes is given by the color sensor implemented, which allows knowing the color temperature of luminary under analysis. The Graphic Unit Interface (GUI) has several characteristics: It can control the meter, acquires the data obtained by the sensor and graphs them in 2D under Cartesian and polar formats or 3D, in Cartesian format. The graph can be exported to png, jpg, or bmp formats, if necessary. These remarkable characteristics differentiate this GUI. This proposal can be considered as a viable option for enterprises of illumination design and manufacturing, due to the relatively low investment level and considering the complete illumination characterization provided.
A complete adjustable and automated system has been developed on the base of three blocks: the first one is the mechanical and adjustable structure, which is composed by a mobile base and a rectangular arc, where the photodetector is located. The structure describes semi-spherical trajectories by means of two servomotors. Its lightweight and robustness constitutes two advantages which make it portable. The second stage corresponds to the automation of the structure movements. For controlling the motors and data acquisition, a microcontroller is employed that in turns helps keeping the cost of the overall system low. One of the servomotors is located on the lateral axis of the device; that displaces the sensor along a semi-circular trajectory of 160°, almost half meridians; the other one is located at the base of the illumination source, which enables it to realize an almost complete rotation around its axis. Finally, the last stage is formed by the graphical interface. The communication protocol between the data acquisition stage and the computer is USART. The graphical user interface (GUI) is developed using Visual C#. In the same window the data acquisition deployment and the data graph generator are given; the graphs can be shown in a polar or Cartesian formats showing more than one curve, if necessary, avoiding the use of additional software. The GUI keeps the low cost of the device, obtaining a comprehensive solution to generate the irradiance patterns of light sources.
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.
The semi-spherical meter uses a photo-detector mounted on a mobile rectangular arc, which by means of two stepper
motors describes the semi-spherical trajectories required. For controlling motors and data acquisition, a Peripheral
Interface Controller (PIC) is employed, which helps keeping the low cost of the overall system. One of the stepper
motors is located on the lateral axis of the device; that displaces the sensor along a semi-circular trajectory of 170°,
almost complete meridians. Another motor located at the base of the device enables 360° rotation of the illumination
source under test. The precision is increased by the using of two angle sensors located on the opposite lateral axis and on
the mobile base of the illumination source. Additionally, before the data obtained from the photo-detector arrive to the
PIC, a stage of signal conditioning is used. This step allows us to increase not only the precision, but also the versatility
of the meter to analyze illumination sources of different sizes and fluxes. The communication protocol between the data
acquisition stage and the computer is USART. A graphical user interface (GUI) is employed on the base of the
The number of measurement points is determined by programming the two motors. The mechanical structure provides
enough rigidity for supporting the accuracy required by the data acquisition circuitry based on a PIC. Measurement of
illumination sources of different sizes is possible by using adjustable lengths of the mobile base and the ring.
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°, almost half meridians. Another motor located at the base of the device enables 360° 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".
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.
Communication systems require devices that allow rapid distribution of signals to multiple users. We presented a
proposal for a demultiplexer based on the fanning effect. Beam fanning is a process similar to two-beam coupling, except
in this case, in where only one beam is incident on the material and its energy is transferred into scattered light. As a
result of the energy transfer, scattered light is amplified, and a "fan" is observed. Since energy transfer direction can be
changed by switching the polarity of the applied electric field, beam fanning effect can be maximized or minimized on
depending of the polarity. We propose an optical router method with the photorefractive beam-fanning. In this method, a
Gaussian modulated beam passing through a photorefractive BaTiO<sub>3</sub> crystals spreads into a some beams that arises from
stimulated scattering. This fanning can be controlled changing the polarization of the beam or the incident angle toward
the crystal. Each scattered beam maintains the input modulated frequency in a wide range. Our results show the possible
application of the fanning effect as an optoelectronic demultiplexer.
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
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.
In this work, the development of a spherical irradiance meter is presented. The illumination intensity measurements are
made by means of a photo-detector assembled on a mechanical setup. The received power by the detector is useful to
obtain the irradiance profile of the lighting source under test, considering a discrete set of points. This detector is located
at the edge of the mobile arm of the mechanical system, which makes a sweep considering two movements directed by
the azimuthal and zenithal angles, generating analogous paths to the terrestrial meridians, covering a semi-sphere of 27
cm of radius. The concentric trajectories consider lighting source under test at their center. The radiation pattern of each
lighting source is generated using the irradiance data and the detector positions.
The mechanical structure has a horizontal mobile base, which allows a 360° rotation. At the same time, one of its
extremes serves as base of the mobile arm, which allows the vertical movements and provides the sensor support. The
movements are controlled by step motors determining the data collection points. They also define the horizontal and
vertical resolution. The obtained data is visualized by means of a display.
In order to determine the irradiance profile of a directive source on a plane XY, we present an arrangement of geometry
similar to conventional scanners. It is formed by two vertical bases of a mobile rail. On this rail, a photodetector is
located, making it able to move from right to left, covering a mesh of 14x15 detection points.
The XY movements of the setup are determined by servo motors, which determine the resolution, but considering the
interest of researchers in this area, and the feasibility to use a table XY for the scanning, we implement its use as a part
of this meter. The detector is located at the corner of the mobile section. The height of the light source under test is
located at the central part of the described area.
The utilization of only one photo-detector was decided with the purpose of a higher homogeneity of the irradiance
measurements. The detector must have high stability and low noise. The resolution XY is determined by the movements
on the axes of a length determined by the DSPIC programming. The use of this device instead of commercial hardware
for data acquisition contributes to the low costs of the prototype. It was realized all the necessary tests for the generation
of reliable information, establishing the time needed to achieve the stability of the system, as well as the levels of noise
due to the presence of the detector and of the electronic elements.
This prototype has a very simple geometry and relatively low cost. It constitutes a good option to determine the
irradiance profile of directive sources.
In this work, we present the basic considerations of a solar follower, realized with a control module based on a Dspic
30F40011. The Dspic was programmed considering the basic equations to track the apparent sun position. The Dspic
programming was realized considering three fundamental blocks: Real time clock, the movement determined by the hour
angle, and the movement determined by the declination angle (based on a CD motor). The mechanical design was
realized considering a parabolic antenna used as concentrator, with a diameter of 60 cm, a depth of 6 cm, weight of
approximately 1.5 kg, made of glass fiber.
The control module is easy to use due to the LCD implementation, which indicates all necessaries entries to the correct
operation of each block. The LCD is also used to display the date, hour, and the temperature obtained by the sensor
temperature located at the antenna focus.
As a proof of the correct system calibration and operation, the shadow of the sensor temperature circuit was located at
the antenna center, during all realized probes. Due to the antenna characteristics, which were made by hands, the amount
of thermal energy is relatively small but for example, enough to heating water. The obtained temperature can be
increased by replace the antenna, without to redesign the mechanical and electronic systems because they can be used for
antennas weight until 15 kg.