Arm Mbed – AWS IoT System Integration [Open access]

This project explores the different Internet of Things (IoT) architectures and the available platforms to define a general IoT Architecture to connect Arm microcontrollers to Amazon Web Services. In order to accommodate the wide range of IoT applications, the architecture was defined with different routes that an Arm microcontroller can take to reach AWS. Once this Architecture was defined, a performance analysis on the different routes was performed in terms of communication speed and bandwidth. Finally, a Smart Home use case scenario is implemented to show the basic functionalities of an IoT system such as sending data to the device and data storage in the Cloud. Furthermore, a Cloud ML algorithm is triggered in real time by the Smart Home to receive a prediction of the current Comfort Level in the room

Graph-search Based UNet-d For The Analysis Of Endoscopic Images

While object recognition in deep neural networks (DNN) has shown remarkable success in natural images, endoscopic images still cannot be fully analysed using DNNs, since analysing endoscopic images must account for occlusion, light reflection and image blur. UNet based deep convolutional neural networks (DNNs) offer great potential to extract high-level spatial features, thanks to its hierarchical nature with multiple levels of abstraction, which is especially useful for working with multimodal endoscopic images with white light and fluoroscopy in the diagnosis of esophageal disease. However, the currently reported inference time for DNNs is above 200ms, which is unsuitable to integrate into robotic control loops. This work addresses real-time object detection and semantic segmentation in endoscopic devices. We show that endoscopic assistive diagnosis can approach satisfy detection rates with a fast inference time

High-efficiency high voltage hybrid charge pump design with an improved chip area

A hybrid charge pump was developed in a 0.13- $\mu \text{m}$ Bipolar-CMOS-DMOS (BCD) process which utilised high drain-source voltage MOS devices and low-voltage integrated metal-insulator-metal (MIM) capacitors. The design consisted of a zero-reversion loss cross-coupled stage and a new self-biased serial-parallel charge pump design. The latter has been shown to have an area reduction of 60% in comparison to a Schottky diode-based Dickson charge pump operating at the same frequency. Post-layout simulations were carried out which demonstrated a peak efficiency of 38% at the output voltage of 18.5 V; the maximum specified output voltage of 27 V was also achieved. A standalone serial-parallel charge pump was shown to have a better transient response and a flatter efficiency curve; these are preferable for time-sensitive applications with a requirement of a broader range of output currents. These findings have significant implications for reducing the total area of implantable high-voltage devices without sacrificing charge pump efficiency or maximum output voltage

The Fabrication and Integration of a 15 MHz Array Within a Biopsy Needle

It is proposed that integrating ultrasound transducer arrays at the tip of tools such as biopsy needles could enable valuable, real-time image feedback during interventional procedures. High-resolution ultrasound imaging has the potential to aid navigation of interventional tools, and to assist diagnosis or treatment via in-vivo tissue characterisation in the breast, amongst many other applications. In order to produce miniature transducer arrays incorporated within biopsy needle-sized packages (2-5 mm diameter), the challenges in micromachining and handling transducer materials at this scale must be overcome. This paper presents fabrication processes used in the micromachining of a 16 element 15 MHz PIN-PMN-PT piezocrystal-polymer composite array and its integration into an 11 G breast biopsy needle. Particular emphasis is given to the manufacturing of the 1-3 dice-and-fill piezocrystal composite, and establishing electrical interconnects. Characterisation measurements have demonstrated operation of each of the 16 elements within the needle case

Periodic shock-emission from acoustically driven cavitation clouds:a source of the subharmonic signal

Single clouds of cavitation bubbles, driven by 254 kHz focused ultrasound at pressure amplitudes in the range of 0.48–1.22 MPa, have been observed via high-speed shadowgraphic imaging at 1 × 10⁶ frames per second. Clouds underwent repetitive growth, oscillation and collapse (GOC) cycles, with shock-waves emitted periodically at the instant of collapse during each cycle. The frequency of cloud collapse, and coincident shock-emission, was primarily dependent on the intensity of the focused ultrasound driving the activity. The lowest peak-to-peak pressure amplitude of 0.48 MPa generated shock-waves with an average period of 7.9 ± 0.5 μs, corresponding to a frequency of f₀/2, half-harmonic to the fundamental driving. Increasing the intensity gave rise to GOC cycles and shock-emission periods of 11.8 ± 0.3, 15.8 ± 0.3, 19.8 ± 0.2 μs, at pressure amplitudes of 0.64, 0.92 and 1.22 MPa, corresponding to the higher-order subharmonics of f₀/3, f₀/4 and f₀/5, respectively. Parallel passive acoustic detection, filtered for the fundamental driving, revealed features that correlated temporally to the shock-emissions observed via high-speed imaging, p(two-tailed) 200 μm diameter, at maximum inflation), that developed under insonations of peak-to-peak pressure amplitudes >1.0 MPa, emitted shock-waves with two or more fronts suggesting non-uniform collapse of the cloud. The observations indicate that periodic shock-emissions from acoustically driven cavitation clouds provide a source for the cavitation subharmonic signal, and that shock structure may be used to study intra-cloud dynamics at sub-microsecond timescales

Improved Performance of d₃₁-Mode Needle-actuating Transducer with PMN-PT Piezocrystal

Prototypes of a PZT-based ultrasound needle-actuating device have shown the ability to reduce needle penetration force and enhance needle visibility with color Doppler imaging during needle insertion for tissue biopsy and regional anesthesia. However, the demand for smaller, lighter devices and the need for high performance transducers have motivated investigation of a different configuration of needle-actuation transducer, utilizing the d 31-mode of PZT4 piezoceramic, and exploration of further improvement in its performance using relaxor-type piezocrystal. This paper outlines the development of the d 31-mode needle actuation transducer design from simulation to fabrication and demonstration. Full characterization was performed on transducers for performance comparison. The performance of the proposed smaller, lighter d 31-mode transducer is comparable with that of previous $d-{33}$-mode transducers. Furthermore, it has been found to be much more efficient when using PMN-PT piezocrystal rather than piezoceramic. </p

Microultraound and small bowel inflammation:Tissue phantom studies

Capsule endoscopy represents a highly convenient but limited means of imaging inflammatory conditions of the small bowel. The inclusion of high frequency microultrasound into a capsule endoscope has the potential to enhance diagnostic capabilities with subsurface imaging of the bowel wall. Experimental studies on abattoir-obtained porcine small bowel have been carried out as an ethical means to characterize healthy and altered tissue in a preclinical setting as well as to explore other means of imaging pathology. Samples of small bowel were cannulated and perfused with phosphate buffered saline followed by variable dilutions of polystyrene microspheres. All samples were scanned with a purpose built step scanner employing a 47 MHz single element transducer. Results indicated that tissue high frequency ultrasound demonstrated sufficient sensitivity to detect the disruption normal histology with microsphere infusion. The combination of microultrasound and capsule endoscopy has the potential to enhance the diagnostic capabilities with improved qualitative and quantitative dimensions