Low Magnetic Field Detection Using a CuPt Nano Structure Made on a SiO2/Si Structure

A Si/SiO2/CuPt structure is formed by depositing a very thin SiO2 layer between CuPt and P-type Si layers using e-beam evaporation. SEM images show the formation of CuPt nano clusters with an average size of less than 100 nm. This structure shows high sensitivity to applied magnetic fields at 77K and at low and high dc voltages such that magnetic field as low as 6 mT is detected using I-V and I–B measurements. The variation of current with various magnetic field strength at the constant voltage shows also an oscillatory behavior. The sensitivity of this structure to magnetic fields is believed to be due to small nano size of the platinum–copper structures as well as their discrete energy states and the tunneling of carriers into the insulating layer. Our results indicate that this structure may be a good candidate for small, simple, low cost and sensitive low magnetic field detectors

Observation and Measurement of Negative Differential Resistance on PtSi Schottky Junctions on Porous Silicon

Nanosize porous Si is made by two step controlled etching of Si. The first etching step is carried on the Si surface and the second is performed after deposition of 75 Å of platinum on the formed surface. A platinum silicide structure with a size of less than 25 nm is formed on the porous Si surface, as measured with an Atomic Forced Microscope (AFM). Differential resistance curve as a function of voltage in 77 K and 100 K shows a negative differential resistance and indicates the effect of quantum tunneling. In general form, the ratio of maximum to minimum tunneling current (PVR) and the number of peaks in I–V curves reduces by increasing the temperature. However, due to accumulation of carriers behind the potential barrier and superposition of several peaks, it is observed that the PVR increases at 100 K and the maximum PVR at 100 K is 189.6

Low Magnetic Field Detection Using a CuPt Nano Structure Made on a SiO2/Si Structure

A Si/SiO2/CuPt structure is formed by depositing a very thin SiO2 layer between CuPt and P-type Si layers using e-beam evaporation. SEM images show the formation of CuPt nano clusters with an average size of less than 100 nm. This structure shows high sensitivity to applied magnetic fields at 77K and at low and high dc voltages such that magnetic field as low as 6 mT is detected using I-V and I-B measurements. The variation of current with various magnetic field strength at the constant voltage shows also an oscillatory behavior. The sensitivity of this structure to magnetic fields is believed to be due to small nano size of the platinum–copper structures as well as their discrete energy states and the tunneling of carriers into the insulating layer. Our results indicate that this structure may be a good candidate for small, simple, low cost and sensitive low magnetic field detectors

Optical system design of star sensor and stray light analysis

Background: Star sensor is one of the precise attitude determination sensors. It is an electro-optical system that takes an image from a set of stars and by comparing it with the star catalogue determines angle deviation of the satellite and modifies its attitude. Star sensor is composed of baffle, optical system, detector, and electronic and image processing system. Methods: In this article, first subsystems of a star sensor is briefly described, then by determining the optical parameters, an optical system with proper quality is designed, and the tolerances are considered. Results: The simulation results and the optical evaluation curves indicate that the image quality is close to the diffraction limit. Next, stray lights from off-axis sources like the sun, are analyzed. For this purpose, the main parameters of baffle designing such as its dimensions and arrangement of the vanes inside it, are determined and then a cylindrical baffle with internal vanes for the star sensor is designed. Conclusion: Results show that stray lights reduced 10− 11 times with the presence of baffle and its vanes

Optical system design of star sensor and stray light analysis

Abstract Background Star sensor is one of the precise attitude determination sensors. It is an electro-optical system that takes an image from a set of stars and by comparing it with the star catalogue determines angle deviation of the satellite and modifies its attitude. Star sensor is composed of baffle, optical system, detector, and electronic and image processing system. Methods In this article, first subsystems of a star sensor is briefly described, then by determining the optical parameters, an optical system with proper quality is designed, and the tolerances are considered. Results The simulation results and the optical evaluation curves indicate that the image quality is close to the diffraction limit. Next, stray lights from off-axis sources like the sun, are analyzed. For this purpose, the main parameters of baffle designing such as its dimensions and arrangement of the vanes inside it, are determined and then a cylindrical baffle with internal vanes for the star sensor is designed. Conclusion Results show that stray lights reduced 10− 11 times with the presence of baffle and its vanes

A sensitive and flexible interdigitated capacitive strain gauge based on carbon nanofiber/PANI/silicone rubber nanocomposite for body motion monitoring

Stretchable nanocomposites-based strain gauges have received much attention due to their adjustable properties in various applications, including soft robotics, human health monitoring, body motion detection, structural health monitoring, and artificial intelligence. Although low sensitivity (gauge factor) is one of the challenges of capacitive strain gauges, in this study, we design, manufacture, and illustrate characterizations of a stretchable interdigitated capacitive strain gauge based on carbon nanofiber/polyaniline/silicone rubber nanocomposite by an improvement in sensitivity with linearity, and low hysteresis. This strain gauge reaches a gauge factor of about 14 over an applied strain of 2% and about 2.8 over an applied strain of 20% and demonstrates linearity with negligible hysteresis. The sensitivity of the strain sensor is enhanced not only by the interdigitated design of electrodes but also by the electrodes’ outstanding electrical conductivity, even in a large strain. Due to its sensitivity, the proposed device is suitable for detecting small and large strains and can be used in wearable applications or straight on the skin for human motion detection

Low-cost hydrophobic layer as a top plate in two-plate digital microfluidics

Digital microfluidics is an emerging technology that is able to manipulate droplets individually. To develop this technology it is needed to use cheaper and more accessible materials for its fabrication. At present, materials commonly used for the hydrophobic layer in these devices are expensive materials that require a legal agreement. In this paper, polydimethylsiloxane (PDMS), which is a common and cheap material in the field of microfluidic, is used as a hydrophobic material for both top and bottom plates of digital microfluidic devices. The droplet cannot be actuated using DC voltage in a surrounding air environment. The reason for the droplet pinning is the high contact angle hysteresis of PDMS surface and considerable thickness of hydrophobic layer on the top plate. In order to overcome this problem, we have exploited a suitable AC voltage (230 Vrms and 8 kHz) as well as changing the surrounding environment to the olive oil. Therefore this paper demonstrates the feasibility of using PDMS as a hydrophobic layer in two-plate digital microfluidics