Millimetre Wave Power Measurement

There is currently no traceable power sensor for millimetre wave frequencies above 110 GHz. This thesis investigates a novel approach to remove this limitation by combining the placement of a uniquely designed microchip directly in waveguide. The design of the chip is novel in that it does not rely on a supporting structure or an external antenna when placed in the waveguide. The performance of the design was primarily analysed by computer simulation and verified with the measurement of a scale model. The results show that it is feasible to measure high frequency power by placing a chip directly in waveguide. It is predicted that the chip is able to absorb approximately 60% of incident power. Any further efficiency would require modification of the chip substrate. However, this proposed design should allow the standards institutes a reference that will enable the calibration of equipment to beyond 110 GHz

Design study of a thermocouple power sensor as a monolithic fin-line

Making traceable power measurements above 110 GHz using current measurement technologies is challenging. We investigate a design of power sensor consisting of a thermocouple-based integrated circuit (IC) mounted as a finline component in WR-6 waveguide. The design is original in that it contains an antenna, terminating resistor and thermocouples on-chip. We detail the design and report results from simulations and measurements made on a two-port 16:1 scale model. Our design of scale model provides both insertion and reflection loss measurements. Electromagnetic simulation and easily-calibrated model measurements confirm that the short antenna fins feasible on a monolithic microwave integrated circuit (MMIC) can achieve acceptable specifications. The design proves to be relatively insensitive to the value of the terminating resistance or the size of the antenna fins

Scaling of Electrode-Electrolyte Interface Model Parameters In Phosphate Buffered Saline

We report how the impedance presented by a platinum electrode scales with the concentration of phosphate buffered saline (PBS). We find that the constant phase element of the model scales with approximately the log of concentration, whereas the resistivity is inversely proportional. Using a novel DC measurement technique we show that the Faradaic response of a platinum electrode, and thus the safe exposure limit, does not scale with concentration below 900mV overpotential across a pair of electrodes. We compare objective measurements made in saline to those made in the spinal cavity of live sheep. We comment upon the appropriateness of using PBS as a substitute for living sheep

The energy efficiency of 8-bit low-power microcontrollers

We have measured the energy cost of processing, sleeping, non-volatile memory writes and ADC measurements of six 8-bit microprocessors from three manufacturers. These measurements compare the chips directly to one another and reveal ideal operating points which can be used to reduce energy consumption

Feasibility of Harvesting Power To Run A Domestic Water Meter Using Streaming Cell Technology

We investigate the possibility of using streaming cells as a means of harvesting energy from the town water supply. We measure the electrical power developed from streaming cells using tap water as a working fluid. We estimate the amount of energy available from a typical domestic household based on water usage data. We estimate the amount of energy required to operate a simple data logger and transmitter. From these estimates we calculate the required efficiency and physical form of a streaming cell energy converter. We comment on the feasibility of using streaming cell technology as a means of harvesting energy from a domestic water supply

Choosing the right microcontroller: A comparison of 8-bit Atmel, Microchip and Freescale MCUs

When choosing a microcontroller there are many options, so which platform should you choose? There is little independent information available to help engineers decide which platform might best suit their needs and most designers tend to stick with the brand with which they are familiar. This is a difficult question to answer without bias if the people conducting the evaluations have had previous experience with MCU programming predominantly on one platform. This article draws on a case study. We built three “Smart” Sprinkler Taps, small, self-contained irrigation controllers, differing only in the microcontroller unit (MCU) on the inside. We compare cost, development software quality and hardware performance from the perspective of a new user to each of the platforms

The Electrical Properties of Interfacial Double Layers

When solids and liquids are brought together, interfacial double-layers are likely to form. They are too small to feel or see so their presence goes mostly unnoticed at the macroscopic level. A double layer is essentially a cluster of ions and/or charged molecules which are drawn from the body of a liquid to the surface of a solid. They are responsible for stabilising some of our most important fluids -- blood, milk, paints, and inks. Without the protection of double-layers, these mixtures clump and lose their fluidity. This thesis examines both electricity generation from, and the electrical impedance of, interfacial double layers. Interfacial double-layers represent the underlying theme of this work, which is broken into two parts. In part I, double layers are used as a means of converting fluid-mechanical energy into electrical energy. My application for this is an energy harvester that could power electronic water meters. Domestic water meters are typically installed where electrical connection is not feasible. Harvesting energy at the meter may make electronic metering a feasible long-term solution. My findings show that double layer based energy harvesters are not efficient enough for this application yet. However, recent literature on the subject suggests large gains in efficiency may be possible using more exotic materials. Such gains would allow a compact harvester to generate enough energy to operate an electronic meter with wireless transmitter. Part II models the electrical impedance of electrodes submerged in electrolytes. Double-layers contribute to the electrical impedance between solid-fluid interfaces. This work is important to designers of medical implants. Engineers use solutions of saline to mimic the environment experienced by their implants once implanted. This provides a way to test implant electronics without putting a patient at risk. A way of characterising the interface between electrodes and an electrolyte is to model it mathematically. An electrical model of an electrode-electrolyte interface was recently developed by my supervisor, Jonathan Scott. I use that model to compare electrodes placed in solutions of saline to those placed in a living animal. Measurements of the two show that no one concentration of saline matches the situation inside a live spinal cavity. I then create a low-cost electrolyte test solution that better matches the impedance measured in a living animal's spinal cavity

Use of electrofishing for capturing invasive fish

Electrofishing is the use of electricity to capture fish. The response of fish to pulsed direct current (DC) occurs in five phases, as shown in Figure 4.5. Electrotaxis occurs as a result of the electrical effect on fish muscles that contract with each electrical pulse, rather than its effect on the central nervous system. Each pulse of electrical current in a pulsed DC field causes the fish’s body to flex; it then relaxes between each of the pulses. This flexing and straightening action accentuates the involuntary swimming towards the anode (galvanotaxis). Pulsed DC causes tetany and narcosis at a much lower voltage gradient than continuous DC, so this is the preferred current delivery (Brousseau et al. 2005). Because invasive fish species inhabit a wide variety of non-wadeable habitats, this chapter will focus on boat electrofishing

Glucagon like peptide-1 receptor agonists as neuroprotective agents for ischemic stroke: a systematic scoping review

Stroke mortality and morbidity is expected to rise. Despite considerable recent advances within acute ischemic stroke treatment, scope remains for development of widely applicable neuroprotective agents. Glucagon like peptide-1 receptor agonists (GLP-1RAs), originally licensed for the management of Type 2 Diabetes Mellitus, have demonstrated pre-clinical neuroprotective efficacy in a range of neurodegenerative conditions. This systematic scoping review reports the pre-clinical basis of GLP-1RAs as neuroprotective agents in acute ischemic stroke and their translation into clinical trials. We included 35 pre-clinical studies, 11 retrospective database studies, 7 cardiovascular outcome trials and 4 prospective clinical studies. Pre-clinical neuroprotection was demonstrated in normoglycemic models when administration was delayed by up to 24-hours following stroke induction. Outcomes included reduced infarct volume, apoptosis, oxidative stress and inflammation alongside increased neurogenesis, angiogenesis and cerebral blood flow. Improved neurological function and a trend towards increased survival were also reported. Cardiovascular outcomes trials reported a significant reduction in stroke incidence with semaglutide and dulaglutide. Retrospective database studies show a trend towards neuroprotection. Prospective interventional clinical trials are on-going, but initial indicators of safety and tolerability are favourable. Ultimately, we propose that repurposing GLP-1RAs is potentially advantageous but appropriately designed trials are needed to determine clinical efficacy and cost-effectiveness

Robotic Pollination - Targeting kiwifruit flowers for commercial application

This paper contains the initial evaluation of a novel platform mounted robotic pollination system. Advancement in artificial pollination is an important step forward in agricultural sectors due to the global decline of natural pollinators. Robotic pollination allows for potentially autonomous, precision operation; however, background research suggested that prior development in the area has been sparse. The featured wet-application robotic pollination system was capable of detecting >70% of flowers whilst driving at a slow-pace through kiwifruit orchard rows. Over 80% of flowers were robotically pollinated