Proceedings of the Cold Electronics Workshop

The benefits and problems of the use of cold semiconductor electronics and the research and development effort required to bring cold electronics into more widespread use were examined

NASA SBIR abstracts of 1991 phase 1 projects

The objectives of 301 projects placed under contract by the Small Business Innovation Research (SBIR) program of the National Aeronautics and Space Administration (NASA) are described. These projects were selected competitively from among proposals submitted to NASA in response to the 1991 SBIR Program Solicitation. The basic document consists of edited, non-proprietary abstracts of the winning proposals submitted by small businesses. The abstracts are presented under the 15 technical topics within which Phase 1 proposals were solicited. Each project was assigned a sequential identifying number from 001 to 301, in order of its appearance in the body of the report. Appendixes to provide additional information about the SBIR program and permit cross-reference of the 1991 Phase 1 projects by company name, location by state, principal investigator, NASA Field Center responsible for management of each project, and NASA contract number are included

Fuzzy logic based temperature control of thermoelectric cooler (TEC) for single photon avalanche diode (SPAD) application

Single photon avalanche diode (SPAD) is a temperature sensitive device. Even a slight variation of temperature can cause unstable performance in quantum efficiency, responsitivity and dark counts. Due to these reasons,unstable temperature could cause overall poor performance of SPAD. It is common for thermoelectric cooler (TEC) to be used as cooling of photodetectors. SPAD was mounted onto the TEC where it needs to be maintained at a constant low temperature under variation of ambient temperature. The system is simulated using Fuzzy Logic Toolbox in MATLAB Simulink. Simulated using P-type fuzzy logic with the set point temperature of 20˚C and ambient temperature of 16˚C, produce a result of -19.44˚C. The P-type fuzzy logic control design has shown a good overall performance where the steady state error is ±0.56˚C, which is equivalent to ±2.8% and the settling time for the output simulation, ts, is 35.91s

Low-Temperature Technologies and Applications

This book on low-temperature technology is a notable collection of different aspects of the technology and its application in varieties of research and practical engineering fields. It contains, sterilization and preservation techniques and their engineering and scientific characteristics. Ultra-low temperature refrigeration, the refrigerants, applications, and economic aspects are highlighted in this issue. The readers will find the low temperature, and vacuum systems for industrial applications. This book has given attention to global energy resources, conservation of energy, and alternative sources of energy for the application of low-temperature technologies

On-chip magnetic cooling of a nanoelectronic device

We demonstrate significant cooling of electrons in a nanostructure below 10mK by demagnetisation of thin-film copper on a silicon chip. Our approach overcomes the typical bottleneck of weak electron-phonon scattering by coupling the electrons directly to a bath of refrigerated nuclei, rather than cooling via phonons in the host lattice. Consequently, weak electron-phonon scattering becomes an advantage. It allows the electrons to be cooled for an experimentally useful period of time to temperatures colder than the dilution refrigerator platform, the incoming electrical connections, and the host lattice. There are efforts worldwide to reach sub-millikelvin electron temperatures in nanostructures to study coherent electronic phenomena and improve the operation of nanoelectronic devices. On-chip magnetic cooling is a promising approach to meet this challenge. The method can be used to reach low, local electron temperatures in other nanostructures, obviating the need to adapt traditional, large demagnetisation stages. We demonstrate the technique by applying it to a nanoelectronic primary thermometer that measures its internal electron temperature. Using an optimised demagnetisation process, we demonstrate cooling of the on-chip electrons from 9mK to below 5mK for over 1000 seconds

Development of suspended thermoreflectance technique and its application in thermal property measurement of semiconductor materials

Doctor of PhilosophyDepartment of Mechanical and Nuclear EngineeringGurpreet SinghThis dissertation details the development of a new scientific tool for the thermal characterization of freestanding micro/nano-scale materials, with specific application to thin films. The tool consists of a custom-designed and calibrated opto-electric system with superior spatial and temporal resolutions in thermal measurement. The tool, termed as Suspended ThermoReflectance (STR), can successfully perform thermal mappings at the submicron level and is able to produce unconstrained thermal conductivity unlike other optical measurement techniques where independent conductivity measurement is not possible due to their reliance on heat capacity. STR works by changing the temperature of a material and collecting the associated change in light reflection from multiple points on the sample surface. The reflection is a function of the material being tested, the wavelength of the probe light and the composition of the specimen for transparent and quasi-transparent materials. Coupling the change in reflection, along the sample’s length, with the knowledge of heat conduction allows for the determination of the thermal properties of interest. A thermal analytical model is developed and incorporated with optical equations to characterize the conductivity of thin films. The analytical model is compared with a finite element model to check its applicability in the STR experiment and data analysis. Ultimately, thermal conductivity of 2 µm and 3 µm thick Si samples were determined using STR at a temperature range of 20K – 350K and compared to literature as a validation of the technique. The system was automated using a novel LabView-based program. This program allowed the user to control the equipment including electronics, optics and optical cryostat. Moreover, data acquisition and real-time monitoring of the system are also accomplished through this computer application. A description of the development, fabrication and characterization of the freestanding thin films is detailed in this dissertation. For the most part, the thin films were fabricated using standard microfabrication techniques. However, different dry and wet etching techniques were compared for minimum surface roughness to reduce light scattering. The best etching technique was used to trim the Si films for the desired thicknesses. Besides, vapor HF was used to avoid stiction-failure during the release of suspended films

Portable Bicycle-Powered Refridgeration

Lack of access to viable, life-saving vaccines is a major public health problem worldwide. Our project objective is to create a feasible, frugal, and environmentally conscious transportation solution for vaccines. Our design for a bicycle-powered refrigeration system can function in both urban environments and rural areas with unreliable electricity and minimal infrastructure. This is enabled by integrating power generation from bicycle kinetic energy, thermoelectric cooling, voltage regulation, temperature control, and heat dissipation subsystems. The system is enclosed in solid housing to protect fragile vials against bumps and crashes and can be adapted to fit onto existing bicycle racks

Portable Thermoelectric Refrigerator

This project created a versatile thermoelectric refrigerator that can be used via a wall outlet. The product is durable and effective. The refrigerator is functional in any ambient temperature, and uses thermoelectric cooling, and work from a standard 120V power outlet. By understanding existing products’ limitations and strengths, this project produced a product that outperforms what’s currently on the market. Many of the existing products’ operating temperature is dependent on the ambient temperature of the surroundings, which is a large drawback. Additionally, most of them take a long time to reach their lowest temperature, around 3 hours. One team member, Josh DiMaggio, did research with the Cal Poly Physics department over the Summer of 2017 on the effectiveness of Peltier devices in refrigeration. Josh discovered that when Peltiers are thermally in series they can create a much larger temperature difference. A Peltier is a thermoelectric cooling device, therefore satisfying the design requirement. Key design challenges included the following: heat transfer through the insulation, power draw, thermodynamic efficiency, structure strength, intuitive interface, along with other crucial factors. Following design, the refrigerator was built, tested, and the preliminary analysis was validated against the test results. There are plenty of existing patents regarding thermoelectric cooling, but only a few like what this project achieved. The final design is presented in this document