Development of a spin-injection device utilising Gadolinium Nitride

<p>In this thesis, the first steps in creating a realisable spin-injection transistor using ferromagnetic semiconductor electrodes are detailed. A spin-injection device utilising the ferromagnetic semiconductor gadolinium nitride has been designed, fabricated and electrically tested. In addition, an experimental setup for future measurements of a spin current in spin-injection devices was adapted to our laboratory-based off one developed by the Shiraishi group at Kyoto University. Issues encountered during fabrication were identified, and an optimal method for fabricating these devices was determined. Gadolinium nitride and copper were used to make the devices on Si/SiO2 substrates. The electrical integrity and applicability of the devices for future measurements of injected spin-current was determined through electrical device testing. Resistance measurements of electrical pathways within the device were undertaken to determine the successful deposition of the gadolinium nitride and copper. IV measurements to determine if the devices could withstand the current required for spin current measurements were done. The durability of the devices through multiple measurement types was observed. It was determined that although spin-injection devices utilising gadolinium nitride can be successfully fabricated, more work needs to be done to ensure that the electrical pathways through the copper and gadolinium nitride can be consistently reproducible to allow spin-injection measurements to be done.</p>

Development of a spin-injection device utilising Gadolinium Nitride

<p>In this thesis, the first steps in creating a realisable spin-injection transistor using ferromagnetic semiconductor electrodes are detailed. A spin-injection device utilising the ferromagnetic semiconductor gadolinium nitride has been designed, fabricated and electrically tested. In addition, an experimental setup for future measurements of a spin current in spin-injection devices was adapted to our laboratory-based off one developed by the Shiraishi group at Kyoto University. Issues encountered during fabrication were identified, and an optimal method for fabricating these devices was determined. Gadolinium nitride and copper were used to make the devices on Si/SiO2 substrates. The electrical integrity and applicability of the devices for future measurements of injected spin-current was determined through electrical device testing. Resistance measurements of electrical pathways within the device were undertaken to determine the successful deposition of the gadolinium nitride and copper. IV measurements to determine if the devices could withstand the current required for spin current measurements were done. The durability of the devices through multiple measurement types was observed. It was determined that although spin-injection devices utilising gadolinium nitride can be successfully fabricated, more work needs to be done to ensure that the electrical pathways through the copper and gadolinium nitride can be consistently reproducible to allow spin-injection measurements to be done.</p>

Considering Pedicle Screw Resistance in Electromyography of the Spine

BACKGROUND Evoked electromyographic (EMG) monitoring of pedicle screws has been shown to be an effective adjuvant to image guidance or direct visualization of pedicle screw placement. Electrical stimulation is delivered to the head of the screw at various intensities until a muscle potential is evoked. This practice is based on the fact that an intact pedicle effectively shields nerve roots from electrical stimulus. Several factors have been debated that may affect the interpretation of results; however, to the best of our knowledge, the electrical resistance of modern manufactured pedicle screws and stimulation devices has not been studied. OBJECTIVE To determine if pedicle screw resistances affect triggered EMG. METHODS Samples of the most commonly implanted pedicle screws in Canada were obtained, with diameters ranging from 4.5 to 7 mm. The resistance between the screw head and thread and core at the midpoint and tip of the screw was recorded using a Multimeter in accordance with IEEE standards. For screws with variable threads, the midpoint was considered the point at which the thread pitch changed. RESULTS All screws had low impedances when tested at the point of the screw, but much higher when the cup is tested. The resistance of different manufactures' screws was significantly different, ranging from 0.514 to 2156 Ohms. CONCLUSION Despite differences in resistance, most screws had resistances in ranges that allow for triggered EMG pedicle integrity testing. Resistance from pedicle screws is an important consideration in EMG monitoring of the spine.

Manufacture and Sensor’s Characterization for Optimizing the Manufacture of Resistance Sensors Based on Tea with Natural Sugar and Artificial Sugar

This research aims to identify sensors. This research was carried out through 3 stages, namely: designing resistance sensors, making resistance sensors, testing resistance sensors. The sensor sheceme by using software Fritzing. The tools used in making these sensors include Power and solder, for materials used are plain PCB, 2.2KΩ resistors, copper wire, paper, pens, rulers, and materials for testing are tea, natural sugar and artificial sugar. Sensor testing is performed in data collection by measuring voltage. Because the data generated is in the form of voltage. By doing 2 variations of the volume of 50ml and 100ml which is done 5 times with each volume repetition. The data obtained is then processed by calculating the mean and its uncertainty. The results of this research provide information that the natural sugar tea voltage for 50ml volume (0.958 ± 0.1916) 80% repeatability. And for 100ml volume (0.884 ± 0.1768) the compatibility is 80%. While the artificial sugar tea voltage for 50ml volume (1.488 ± 0.2976) 80% compatibility and for 100ml volume (1.484 ± 0.2968) 80% repeability. From the data obtained, both can be seen to have different voltage values and the same compatibility value, which is 80%. Because the resulting repeatability does not reach national standards, this sensor cannot be used.