An Easy Method to Discuss Properties of Simplified Solid-state Tesla Coil
Wireless transmission products are widely used in our daily life. In this research, we focus on knowing how solid-state tesla coil works in different conditions and finding the best parameters through an easy way. In our work, a commercial electroscope was used as detector for measuring the strength of radio wave created by our simplified tesla coils. In fact, many factors would lead to experimental erorrs such as detectors, selected types of NPN BJT components, applied voltage and measuring position of height. Therefore, all of the factors were under control to make sure of accuracy and precision for our designed measuring method. In our experiment, graphics of radio wave distribution around tesla coils were drew by mathemetic software of GeoGebra. It shows the BJT types of 2n2222 had good performance for wireless transmisstion efficiency. To our surprised, we found the extended wires (called antenna) from the top of tesla coil also had an ability to transfer electromagnetic energy, and had good retention if the extended wires were within the length of main coil’s height. Finally, the shape’s and size’s effect was determined by our testing work. The result shows that pipe’s length, pipe’s diameter and turns ratio of two coils had great influence on tesla coil’s transmission efficiency. It was found that the tesla’s performance would be more efficient if wire was used to make the length twice rather than make the diameter twice. However, the turns ratio of secondary coil to primary coil would change while making the length twice. To avoid that, we fixed the length and decrease the turns of primary coil. At last, we found tesla coil must work at the turns of primary coil higher than two. Furthermore, the frequency of radio wave not only had less relationship with their length or diameter but also had less relationship with types of BJT In our study, our handmade tesla coil was succesfully applied for wireless charging and we find that the induced voltage decrease in propotion to cube root of distance between tesla coil and induced coil.
Hydrogen Functionalization of Graphene using RF Plasma for photodetection
The growth of the internet is propelling an ever-increasing need for faster communication. Modern telecommunication data is mainly carried through fibre-optic cables, with pulses of light representing bits of data; the main factor limiting data transfer speed is the rate at which the optical receiver at the opposite end of the cable can detect light pulses. Graphene-silicon Schottky photodiodes are a promising alternative to traditionally-used germanium photodiodes, promising higher detection frequency and better contrast between light and dark. To make it less susceptible to erroneous measurements due to graphene having a low band gap, hydrogen functionalisation was used to increase the barrier potential of the Schottky diode so that a higher voltage would be required to allow current to pass through in forward voltage bias and trigger the sensor. This study seeks to determine the optimal conditions — of physical proximity, duration of exposure, and plasma power — for hydrogen functionalisation using radio frequency plasma. Graphene was synthesised using low pressure chemical vapour deposition, then transferred onto P-type silicon to create a photodiode. The graphene-silicon photodiode was then doped with hydrogen plasma to introduce defects in the graphene layer to increase the barrier potential of the photodiode. To assess the effectiveness of hydrogen functionalisation, photocurrent measurements were conducted while light was shone onto the photodiode in pulses of increasing frequency to find the magnitude and spontaneity of the response. Light was shone in pulses of 100ms, and was successfully detected by the photodiode. The pulse spacings were gradually decreased and it was found that the diode was able to detect pulse spacings as low as 1µs, significantly better than germanium photodetectors. The sample demonstrated clear optoelectronic response and was sensitive to changes in frequency. Results show that the intensity of the optoelectronic response in graphene-silicon diodes is inversely related to its physical proximity to the plasma source during hydrogen functionalization; and directly related to the power of the plasma and to the duration of exposure up to a point, after which it will deteriorate. Thus, it can be concluded that graphene-silicon Schottky diodes offer much promise in electronic communication.
CONTACTLESS AND NON-DESTRUCTIVE DETECTION OF CHICKEN MEAT CONTAMINATION WITH LASER SPECKLE METHOD
Harmful microorganisms in food can cause deterioration of human health, poisoning and in some cases even death. Especially fresh meat and chicken products create a suitable environment for the growth of microorganisms in terms of the nutrients it contains, water activity and pH level. For this reason, detection of microorganisms in meat products is an important issue in terms of food safety and human health. In this project, it is aimed to detect live microorganisms in meat products, especially chicken meat, in a simple, non-destructive, non-contact and fast way using laser speckle method. Laser speckle images of healthy and stale chicken meat were taken, contrast parameter and correlation analysis of the obtained patterns were made. It was observed that the contrast parameter for staled chicken meat increased by approximately 3 times compared to fresh chicken. This increase provides an understanding of the difference between contaminated chicken and fresh chicken. Speckle density changes over time in relation to the movements of living microorganisms. Thus, the correlation in laser speckle density patterns taken from contaminated tissues is disrupted. In the measurements taken with photodiode, by analyzing the change of light intensity of the speckle patterns on fresh and contaminated tissues over time, the detection of microorganisms was made easier and more precisely without the need for image processing. The proposed measurement system is a new method that detects meat contamination with laser speckle imaging. It can be developed and made portable and can be used easily in homes. Since it is a simple, non-destructive and fast method, it can be used to determine the shelf life of meat in food distribution places and markets. In addition, it has the potential to be calibrated and used for other food products other than meat products. The system developed with this study is cheap and easy to use, and the laser speckle imaging method is used in a different field other than biomedical, contributing to the literature.