A Synthetic Phased Array Surface Acoustic Wave Sensor for Quantifying Bolt Tension

In this paper, we report our findings on implementing a synthetic phased array surface acoustic wave sensor to quantify bolt tension. Maintaining proper bolt tension is important in many fields such as for ensuring safe operation of civil infrastructures. Significant advantages of this relatively simple methodology is its capability to assess bolt tension without any contact with the bolt, thus enabling measurement at inaccessible locations, multiple bolt measurement capability at a time, not requiring data collection during the installation and no calibration requirements. We performed detailed experiments on a custom-built flexible bench-top experimental setup consisting of 1018 steel plate of 12.7 mm (1/2 in) thickness, a 6.4 mm (in) grade 8 bolt and a stainless steel washer with 19 mm (3/4 in) of external diameter. Our results indicate that this method is not only capable of clearly distinguishing properly bolted joints from loosened joints but also capable of quantifying how loose the bolt actually is. We also conducted detailed signal-to-noise (SNR) analysis and showed that the SNR value for the entire bolt tension range was sufficient for image reconstruction

Damariçi yanabakan ultrasonik görüntüleme için statik dizi ve demetleme devresi yapıları

Text in English; Abstract: English and TurkishIncludes bibliographical references (leaves 54-55)xiv, 60 leavesCurrent solid-state intravascular ultrasound (IVUS) devices use a one-dimensional (1-D) rectangular array wrapped around the cylindrical catheter. Beamforming in these devices is limited to synthetic phased array processing, and the image quality is degraded by low signal to noise ratio (SNR) and lack of focusing in elevation. We propose new solid-state reconfigurable cylindrical array configurations, based on non-uniform aperture sampling, enabling realization of low-cost integrated phased array beamformers based on the latest IC and transducer integration techniques. We employed non-uniform (Fresnel) aperture sampling with identical differential delays between adjacent elements to reduce dynamic beamformer complexity. For this purpose, the angles of the element boundaries and centers are determined by equalizing path difference of neighboring elements. For Side Looking-IVUS (SLIVUS), the image plane is scanned through stepping the active aperture, and the active array must be reformed in each step. Fresnel sampled ring array leads to a simplified phased array beamformer with N/2 identical differential delays. The same logic applies to a two-dimensional (2-D) array with NL×NE-elements over a cylindrical patch. We compared the proposed and existing array designs through numerical point spread function (PSF) simulations. The uniform and Fresnel sampled 1-D ring arrays perform similarly in terms of beam quality while the latter improves image SNR by a factor of √NL due to synthetic vs full phased array processing. The Fresnel sampled 2-D array performs dramatically better in elevation compared to 1-D ring array. The additional contribution of 2-D array on image quality is high SNR produced by phased array beamforming. The proposed Fresnel sampling of cylindrical aperture simplifies phased array beamformer by halving the required delay element count and transforms the complex 2-D beamformer into a separable beamformer that requires simple 1-D beamformers. The resulting 1-D and 2-D SLIVUS array configurations could be realizable using monolithic integration of the analog beamformers with transducer arrays.Günümüzde kullanılan damar içi ultrasonik kateterler, statik kateterler, silindirik bir boyutlu (1-D) dizi yapıları kullanmaktadırlar. Bu yapılarda, derinlik yönünde dizi uzantısı olmadığından bu yönde demetleme yapılamaması ve yerleştirilen yüksek yoğunluklu dizi için gerekli kanal sayısı en temel problemlerdir. Artan kanal sayısı yapay dizi tekniğini kullanmayı zorunlu kılar ki bu teknik SNR değerini yükseltmektedir. Önerilen değişken boyutlu örneklenmiş (Fresnel örneklenmiş) statik dizi yapıları demetleme devrelerini basitleştirerek hem kateter üzerine iki boyutlu dizi yapıları yerleştirmeyi mümkün kılar hem de azalan kanal sayısı ile evreli dizi kullanılabilir. Fresnel örnekleme tekniği komşu elemanlara uygulanacak gecikme farklarının birbirinin aynısı olmasını sağlamalıdır ki bu gereken demetleme devresinin büyüklüğünü dramatik olarak düşürmektedir. B-scan görüntüsü elde etmek için silindirik dizi üzerinde bir alt-dizi seçilir ve lateral yönde kaydırılır. Her kaydırma adımında alt-dizi yeniden oluşturulmaktadır ve N/2 adet kanal kullanarak demetleme yapmaktadır. Aynı prensibi ikinci boyuta da uygularsak, kaydırılan 2- boyutlu (2-D) alt dizi NL/2×NE/2 kanal kullanacak ve ayrıca eksenel simetri sayesinde her eleman ile ilgili iki boyuta ait gecikmeler birbirinden ayrılabilecektir. Bahsedilen yöntemle elde edilen dizi yapıları, mevcut yapılar ile demetleme devreleri kompleksliği ve görüntü kaliteleri açısından numerik PSF benzetimleri kullanılarak karşılaştırılmıştır. Elde edilen sonuçlar Fresnel örneklenmiş dönüştürücüler ile tekdüze örneklenmiş dönüştürücülerin benzer sonuç verdiğini göstermiştir. Farklı olarak Fresnel örneklenmiş yapılar SNR seviyesini yükseltmektedir. Derinlik yönündeki dizi bu yöndeki çözünürlüğü ciddi bir biçimde iyileştirmiştir. Fresnel örnekleme bir yöndeki gecikme elemanı sayısını yarıya indirerek evreli demetleme elektroniğini basitleştirir, ayrıca 2-D dizide her eleman için her iki boyuttaki gecikme miktarının ayrıştırılabilir hale gelmesi 2-D demetleme devresinin basit 1-D demetleme devrelerinin birleşimi ile yapılabilmesini sağlar

Numerical and Experimental Studies on the Effect of Surface Roughness and Ultrasonic Frequency on Bubble Dynamics in Acoustic Cavitation

With many emerging applications such as chemical reactions and ultrasound therapy, acoustic cavitation plays a vital role in having improved energy efficiency. For example, acoustic cavitation results in substantial enhancement in the rates of various chemical reactions. In this regard, an applied acoustic field within a medium generates acoustic streaming, where cavitation bubbles appear due to preexisting dissolved gas in the working fluid. Upon cavitation inception, bubbles can undergo subsequent growth and collapse. During the last decade, the studies on the effects of different parameters on acoustic cavitation such as applied ultrasound frequency and power have been conducted. The bubble growth and collapse mechanisms and their distribution within the medium have been classified. Yet, more research is necessary to understand the complex mechanism of multi-bubble behavior under an applied acoustic field. Various parameters affecting acoustic cavitation such as surface roughness of the acoustic generator should be investigated in more detail in this regard. In this study, single bubble lifetime, bubble size and multi-bubble dynamics were investigated by changing the applied ultrasonic field. The effect of surface roughness on bubble dynamics was presented. In the analysis, images from a high-speed camera and fast video recording techniques were used. Numerical simulations were also done to investigate the effect of acoustic field frequency on bubble dynamics. Bubble cluster behavior and required minimum bubble size to be affected by the acoustic field were obtained. Numerical results suggested that bubbles with sizes of 50 µm or more could be aligned according to the radiation potential map, whereas bubbles with sizes smaller than 10 µm were not affected by the acoustic field. Furthermore, it was empirically proven that surface roughness has a significant effect on acoustic cavitation phenomena

Design and implementation of a low cost telematic control system

Text in English; Abstract: English and TurkishIncludes bibliographical references (leaves 54)vii, 57 leavesThe thesis explains phases from ideation to concretize of a device that aims to solve continuously increase security needs in everyday life more effective, more reliable and cheaper way; however the device has so many application fields such as home automation projects, factory automation, SCADA systems, alarm and security systems, agricultural watering systems etc. A device that controls any desired event has been occurred, then informs the user over GSM, or activates any other electronic device when the user sends an SMS message over GSM, has been designed and realized in this thesis. All of the adjustments can be configured by user via SMS and serial port. Also all of the inform messages and output setting messages can be configured by serial port. For example, device's first input can be configured to send such a message 2Alert!3 when it is activated.GSM üzerinden data haberleşmesi çok kullanışlı ve modüler olmasına karşın fazla yaygınlaşamamıştır. Özellikle mobilite rekabet edilemez bir özelliktir. Fazla yaygınlaşmama nedeni araştırıldığında ana sebebin aşırı üretim maliyetinin ürün fiyatına yansıması olduğu anlaşılmıştır. Sonuçta bireysel kullanıcılar bir yana kurumsal kullanıcıların dahi bu teknolojiye sahip olamadıkları görülmüştür. Söz konusu cihazların maliyet analizi yapıldığında maliyeti arttıran en önemli unsurun GSM modülü olduğu anlaşılmıştır. Bu durumda piyasada bol miktarda bulunan ve ucuz olan bir GSM modulü araştırılmış, Ericsson GSM telefonları uygun bulunmuştur. Ericsson telefonları bir GSM modülü olarak kullanılması için neler yapılması gerektiği araştırılmış ve bu telefonlar için haberleşme protokolü çözülmüştür. Bu sayede hedeflenen cihazın maliyet bireysel kullanım için bile uygun hale gelmiş ve söz konusu cihaz daha önceden uygulamada kendine yer bulamayan alanına bir çok yeni alanda da düşük maliyetten dolayı uygulama sahasına girmeye fırsat bulmuştur

A Urinary Bcl-2 Surface Acoustic Wave Biosensor for Early Ovarian Cancer Detection

In this study, the design, fabrication, surface functionalization and experimental characterization of an ultrasonic MEMS biosensor for urinary anti-apoptotic protein B-cell lymphoma 2 (Bcl-2) detection with sub ng/mL sensitivity is presented. It was previously shown that urinary Bcl-2 levels are reliably elevated during early and late stages of ovarian cancer. Our biosensor uses shear horizontal (SH) surface acoustic waves (SAWs) on surface functionalized ST-cut Quartz to quantify the mass loading change by protein adhesion to the delay path. SH-SAWs were generated and received by a pair of micro-fabricated interdigital transducers (IDTs) separated by a judiciously designed delay path. The delay path was surface-functionalized with monoclonal antibodies, ODMS, Protein A/G and Pluronic F127 for optimal Bcl-2 capture with minimal non-specific adsorption. Bcl-2 concentrations were quantified by the resulting resonance frequency shift detected by a custom designed resonator circuit. The target sensitivity for diagnosis and identifying the stage of ovarian cancer was successfully achieved with demonstrated Bcl-2 detection capability of 500 pg/mL. It was also shown that resonance frequency shift increases linearly with increasing Bcl-2 concentration

A novel numerical model to simulate acoustofluidic particle manipulation

Acoustofluidic systems are attracting more attention in recent years because of their specifications, like versatility, high biocompatibility, high controllability, and simple design. However it is important to optimize the system parameters, which affects system performance. Simulation techniques have a crucial role in optimization since high fabrication costs limit the number of runs. However, the complex Multiphysics structure of the system makes the optimization process very elaborate. Here, an innovative and feasible numerical method to simulate and optimize the acoustofluidic particle manipulation process is reported. The proposed numerical method consists of three main steps. In the first step, surface acoustic waves are generated and propagated on a piezoelectric substrate. Next, the particle motion under the effect of the acoustophoresis force is simulated using successive two-dimensional models representing the different regions along the microfluidic channel. Finally, the particle trajectory is calculated using the superposition method. The proposed numerical method was validated using a reference experimental study available in the literature. The proposed method successfully simulated the separation of particles with diameters of 10 and 15 mu m. This numerical method can be used as an optimization tool for acoustofluidic particle manipulation systems

A Low-cost Biomarker-based SAW-Biosensor Design for Early Detection of Prostate Cancer

Early detection of prostate cancer is crucial for the treatment. Currently rectal examination, ultrasound and ELISA test for blood-PSA biomarker level are used for diagnosis. However these methods require professional assistance that makes point-of care (POC) testing impossible. A POC, low-cost, high-precision biosensor can increase the early-detection and survival rates. Recently, we have proposed a low-cost and an easy-to-use surface acoustic wave biosensor that enables the quantification of PSA level. In this study, we focused to the electronic circuitry and signal processing algorithms for accurate protein level assessment using cost efficient and low-profile hardware. Simplifying the hardware will potentially lead to the development of single chip monolithic integrated biosensor. The MEMS based biosensor designed in our studies utilizes shear-horizontal (SH) SAWs on ST-cut Quartz substrate to sense the mass loading change by protein adhesion. The driver circuitry employs signal-processing algorithms to detect the phase change, which quantifies the protein level in the sample dropped on the surface. The signal applied to the sensor input is a 16.9 MHz square wave generated by using a simple counter circuit. The output is under-sampled at an extremely low rate (100 KHz), then, the phase information is extracted using the under-sampled signal. A low-profile microcontroller (mu C) is used to determine the phase shift. The simulated and experimental results are demonstrated, and they agreed well with each other. The results show that, the phase error level is 1% and minimum delay measured is 0.3 ns. Increasing number of samples used for calculation enhances the detection performance. Our studies also showed that using excessive number of samples enables the accurate phase calculation even if a simple 1-bit ADC is employed. (C) 2017 The Authors. Published by Elsevier Ltd

A novel numerical model to simulate acoustofluidic particle manipulation

Acoustofluidic systems are attracting more attention in recent years because of their specifications, like versatility, high biocompatibility, high controllability, and simple design. However it is important to optimize the system parameters, which affects system performance. Simulation techniques have a crucial role in optimization since high fabrication costs limit the number of runs. However, the complex Multiphysics structure of the system makes the optimization process very elaborate. Here, an innovative and feasible numerical method to simulate and optimize the acoustofluidic particle manipulation process is reported. The proposed numerical method consists of three main steps. In the first step, surface acoustic waves are generated and propagated on a piezoelectric substrate. Next, the particle motion under the effect of the acoustophoresis force is simulated using successive two-dimensional models representing the different regions along the microfluidic channel. Finally, the particle trajectory is calculated using the superposition method. The proposed numerical method was validated using a reference experimental study available in the literature. The proposed method successfully simulated the separation of particles with diameters of 10 and 15 μm. This numerical method can be used as an optimization tool for acoustofluidic particle manipulation systems

Tıbbi ultrasonik kanal içi görüntüleme için yeni yöntemler

Yakın zamanda yapılan çalışmalarımızdaki yaklaşımda, aktif kanal sayısını azaltmak için fazlalık (redundant) gönderme-alma eleman ikilileri azalırken gerekli olan (non-redundant) gönderme-alma eleman ikilileri korunmaktadır. Bu işlem, rastgele değil tek düze bir eşdeğer dizi açıklık işlevi oluşturmaya yönelik olarak belirlilik yaklaşımına (deterministik) dayalı yapılmaktadır. Bu yaklaşıma dayalı olarak fazlalık mekânsal frekansları azalmış çok fazla dizi yapıları oluşturmak olanaklıdır. Tasarlanan bazı dizi yapıları yakın tarihli uluslararası bir konferansta grubumuzca sunulmuştur. Bu yapılar, küçük diziler (örneğin NxN=16x16) için gerçek zamanda görüntülemeye olanak vermekle beraber büyük diziler için (örneğin NxN=32x32 ve NxN=64x64) gerçek zamanda görüntüleme için uygun değildir. Bu projede önerilen yeni yaklaşımda, görüntü uzayının taranma zamanını kısaltmak ve böylece görüntüleme hızını artırmak amacıyla, görüntü uzayı, göndermede yelpaze-demet (fanbeam) kullanılarak taranmaktadır. Bu yaklaşım, fazlalık mekânsal frekansları azaltılmış dizilerle yapılan görüntülemenin hızını, dizi büyüklüğünün kareköküne indirgeyerek büyük dizilerle gerçek zamanda görüntülemeye olanak vermektedir. Yaklaşımın bu özelliği esas alınarak, fazlalık mekânsal frekansları tamamen ayıklanmış yeni bir özgün dizi yapısı düşünülmüş ve yelpaze-demetleme yaklaşımı ile birlikte bir bütün olarak kullanılması öngörülmemiştir. Bu proje çalışmasında, fazlalık mekânsal frekansları azaltılmış ve tamamen ayıklanmış dizi yapıları yelpaze-demetleme yaklaşımıyla birlikte teorik olarak ve sayısal benzetim yoluyla irdelenmiş, ön-elektronik donanım mimarileri oluşturulmuştur. Projede önerilen yaklaşımın sistem maliyeti bakımından bir boyutlu dizi kullanan sistemlere yakın ve görüntüleme performansı üç boyutlu kanal içi görüntülemeye uygun olduğu, teorik ve benzetimsel nitel ve nicel sınamalarla gösterilmiş ve proje amaçlarına ulaşılmıştır.TÜBİTA