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1.
Ultrasonics ; 104: 106108, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32145443

RESUMO

High intensity focused ultrasound (HIFU) has great potential to thermally ablate diseased tissues with minimal invasion. Yet, HIFU practice has limited cancer treatment potential since the absorption, diffusion, and reflection of ultrasound prevent HIFU from penetrating the body to deep and concealed diseased tissue. To explore a vision of deployable HIFU transducers, this research introduces an origami-inspired concept wherein a deployable tessellated acoustic array is employed to reduce the distance between the HIFU transducer and diseased tissues. A flat-foldable HIFU transducer array is considered, such that the compact shape is used to pass through the human body and then deployed into the operational form for treatment. Here a theoretical framework is developed to study the focusing and thermal heating capabilities of the tessellated array in a multilayer environment. It is observed that the wavefield and thermal elevation realized by the foldable array are functionally similar to those of an ideal arc-shaped transducer. Folding patterns that permit adequate curvature and high quality factor, and that balance slenderness and conformability are found to be beneficial for an ultrasound focusing practice. The efficacy of the analytical predictions are verified through direct numerical simulations. All together, the results encourage attention to foldable array concepts as potential means to advance in-vivo HIFU-based procedures.


Assuntos
Ablação por Ultrassom Focalizado de Alta Intensidade/instrumentação , Transdutores , Acústica , Desenho de Equipamento , Análise de Elementos Finitos , Temperatura Alta , Propriedades de Superfície
2.
Ultrasonics ; 104: 106093, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32151876

RESUMO

Color Doppler (CD) ultrasound has been commonly employed in biomedical field to get hemodynamic information. However, reliable diagnostic evaluation and criteria for vascular diseases may not be provided due to technical limitations of CD, including single-directional measurement, aliasing, and limited imaging conditions. In this study, adaptive hybrid (AH) scheme is proposed to enhance measurement accuracy of conventional CD. It can improve the accuracy of velocity field measurement by replacing erroneous vectors in the measured CD results with the correct vectors obtained from a speckle image velocimetry (SIV) technique. The performance of the proposed AH technique was validated through in vitro experiments for various flow rates and insonation angle conditions, comparing conventional velocimetry techniques. The in vitro experiments demonstrated that the AH technique could measure flow velocity with better accuracy than the CD with bias errors of below 0.7 mm/s. The clinical applicability of the AH was also validated by measuring venous flows at human lower extremity, checking constant volumetric flow rates. Flow rates measured by the AH were maintained along the vein, while the CD and SIV results varied. As a result, the AH can provide improved measurement accuracy without installing a new supplementary equipment. It would be effectively utilized for analyzing flow dynamics and diagnosing valve-related disease.


Assuntos
Velocidade do Fluxo Sanguíneo/fisiologia , Extremidade Inferior/irrigação sanguínea , Ultrassonografia Doppler em Cores/métodos , Doenças Vasculares/diagnóstico por imagem , Adulto , Algoritmos , Feminino , Humanos , Aumento da Imagem , Masculino , Imagens de Fantasmas , Transdutores
3.
Ultrasonics ; 103: 106067, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32018093

RESUMO

Controlled capture of single biological micro particles, with effective capture function, little heat damage to and good stability of captured samples simultaneously, has been a technological challenge in the area of micro manipulation. This paper presents an ultrasonic tweezers based new strategy to meet the challenge. In the strategy, being different from the other ultrasonic methods, the MMP (micro manipulating probe), which vibrates elliptically, is in contact with the substrate. Single yeast cells with a diameter of 3-7 µm and Chlorella vulgaris powders with a diameter of 2-10 µm near the MMP can be sucked onto the MMP's tip. The captured particle can be transferred to a desired location at the interface between the water film and substrate by moving the ultrasonic tweezers. The temperature rise in the capture region is less than 0.1 °C, and the sucking distance can be up to 20 µm. The captured particle is in contact with the MMP's tip, which results in a good stability of the captured particle. The experiments also show that it is possible to use multiple MMPs to individually capture single cells. The finite element analyses indicate that acoustic radiation force generated by the ultrasonic field around the MMP is responsible for the capture. Moreover, the effects of the orthogonal vibration components, tilt angle and length of the MMP on the capture capability are clarified.


Assuntos
Micromanipulação/instrumentação , Ultrassom/instrumentação , Chlorella vulgaris , Desenho de Equipamento , Análise de Elementos Finitos , Tamanho da Partícula , Pós , Temperatura Ambiente , Transdutores , Vibração , Água , Leveduras
4.
Ultrasonics ; 103: 106086, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32070827

RESUMO

Ultrasonic bioreactors have been used for in vitro experimentation to study cellular responses to low-intensity pulsed ultrasound. The presence of an air interface in these bioreactors contributes to variability in the acoustic pressure field, reducing experimental reproducibility. A multiphysics finite element model was developed to simulate the acoustic field in an in-dish ultrasonic bioreactor, where the transducer is immersed in culture medium above the dish surface, and the effects of replacing air below the dish in the bioreactor with a water layer bounded by an acoustic absorbent layer were evaluated. Frequency domain simulations showed that the spatially-averaged pressure at the dish surface alternated between a minimum and maximum level as the distance between the dish and transducer increased. The ratio of the maximum to minimum level was 6.5-fold when the air interface was present, and this ratio dropped to 1.8-fold with replacement of the air interface. However, radial pressure variability was present with or without the air interface in the bioreactor model. Time-dependent simulations showed that the increase in acoustic pressure to a maximum level after US signal activation and the pressure drop after signal cessation were faster when the water-coupled non-reflective layer was used to replace the air layer below the dish, generating a pressure pattern that more closely followed the applied pulsed ultrasound signal due to reduced wave reflection and interference. Overall, this work showed that having water rather than air in contact with the lower dish surface when paired with an acoustic absorbent layer resulted in a less variable pressure field, providing an improved bioreactor design for in vitro experiments.


Assuntos
Acústica , Reatores Biológicos , Análise de Elementos Finitos , Fenômenos Biofísicos , Meios de Cultura , Desenho de Equipamento , Pressão , Software , Propriedades de Superfície , Transdutores , Ultrassom , Água
5.
Bioelectromagnetics ; 41(1): 21-33, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31755122

RESUMO

The present study is part of an ongoing effort to develop a simple diagnostic technology for detecting internal bleeding in the brain, which can be used in lieu or in support of medical imaging and thereby reduce the cost of diagnostics in general, and in particular, would make diagnostics accessible to economically disadvantaged populations. The study deals with a single coil inductive device to be used for detecting cerebral hemorrhage. It presents a first-order experimental study that examines the predictions of our recently published theoretical study. The experimental model employs a homogeneous cylindrical phantom in which internal head bleeding was simulated by way of a fluid inclusion. We measured the changes in amplitude and phase across the coil with a network vector analyzer as a function of frequency (100-1,000 MHz), volume of blood simulating fluid, and the site of the fluid injection. We have developed a new mathematical model to statistically analyze the complex data produced in this experiment. We determined that the resolution for the fluid volume increase following fluid injection is strongly dependent on frequency as well as the location of liquid accumulation. The experimental data obtained in this study supports the predictions of our previous theoretical study, and the statistical analysis shows that the simple single coil device is sensitive enough to detect changes due to fluid volume alteration of two milliliters. Bioelectromagnetics. 2020;41:21-33 © 2019 Bioelectromagnetics Society.


Assuntos
Determinação do Volume Sanguíneo/métodos , Simulação por Computador , Imagens de Fantasmas , Acidente Vascular Cerebral/diagnóstico , Volume Sanguíneo , Condutividade Elétrica , Campos Eletromagnéticos , Desenho de Equipamento , Transdutores
6.
Sensors (Basel) ; 19(19)2019 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-31590351

RESUMO

Blood pressure wave monitoring provides interesting information about the patient's cardiovascular function. For this reason, this article proposes a non-invasive device capable of capturing the vibrations (pressure waves) produced by the carotid artery by means of a pressure sensor encapsulated in a closed dome filled with air. When the device is placed onto the outer skin of the carotid area, the vibrations of the artery will exert a deformation in the dome, which, in turn, will lead to a pressure increase in its inner air. Then, the sensor inside the dome captures this pressure increase. By combining the blood pressure wave obtained with this device together with the ECG signal, it is possible to help the screening of the cardiovascular system, obtaining parameters such as heart rate variability (HRV) and pulse transit time (PTT). The results show how the pressure wave has been successfully obtained in the carotid artery area, discerning the characteristic points of this signal. The features of this device compare well with previous works by other authors. The main advantages of the proposed device are the reduced size, the cuffless condition, and the potential to be a continuous ambulatory device. These features could be exploited in ambulatory tests.


Assuntos
Monitorização Ambulatorial da Pressão Arterial/métodos , Pressão Sanguínea/fisiologia , Monitorização Fisiológica , Análise de Onda de Pulso/métodos , Adulto , Monitorização Ambulatorial da Pressão Arterial/instrumentação , Eletrocardiografia/métodos , Feminino , Frequência Cardíaca/fisiologia , Humanos , Masculino , Fotopletismografia/métodos , Análise de Onda de Pulso/instrumentação , Transdutores
7.
Environ Monit Assess ; 191(11): 657, 2019 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-31630271

RESUMO

Iran has experienced a severe drought during the past two decades. Increasing water demand and decreasing available water resources have led the country to critical conflicts, particularly in shared watersheds. In these basins, the precise measurement of releasing water from upstream to downstream can be a key data for resolving water conflicts. The Iranian Ministry of Energy (MOE) makes the streamflow measurements through regional water administrative offices, mainly using the classical rating curve (RC) method. The documented measurements of runoff by adjacent offices usually present different estimations of the water resources, due to high uncertainties of the RC approach. Fluvial acoustic tomography (FAT) is a reliable technology for continuously monitoring streamflow, which can be implemented to solve this problem of shared basins. In this study, FAT is applied to the Zayanderud basin, an Iranian shared watershed and its results are compared with the RC methods. The main terms of FAT streamflow measurement uncertainty are velocity resolution component, and the selected flow angle between the stream direction and acoustic transmission path. Therefore, a new equation is proposed to carefully choose accurate angles for different river widths to decrease FAT measurement error in this paper. The obtained results show that the measured streamflow by FAT and RC are 9.89 m3/s and 10.3 m3/s, respectively, and the largest possible error of FAT is less than 15%.


Assuntos
Acústica/instrumentação , Monitoramento Ambiental/métodos , Hidrodinâmica , Rios , Monitoramento Ambiental/instrumentação , Irã (Geográfico) , Transdutores
8.
Sensors (Basel) ; 19(20)2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31623215

RESUMO

Current cochlear implant (CI) systems provide substantial benefits for patients with severe hearing loss. However, they do not allow for 24/7 hearing, mainly due to the external parts that cannot be worn in all everyday situations. One of the key missing parts for a totally implantable CI (TICI) is the microphone, which thus far has not been implantable. The goal of the current project was to develop a concept for a packaging technology for state-of-the-art microelectromechanical systems (MEMS) microphones that record the liquid-borne sound inside the inner ear (cochlea) as a microphone signal input for a TICI. The packaging concept incorporates requirements, such as biocompatibility, long-term hermeticity, a high sensing performance and a form factor that allows sensing inside the human cochlea and full integration into the existing CI electrode array. The present paper (1) describes the sensor packaging concept and the corresponding numerical and experimental design verification process and (2) gives insight into new engineering solutions for sensor packaging. Overall, a packaging concept was developed that enables MEMS microphone technology to be used for a TICI system.


Assuntos
Implantes Cocleares , Orelha Interna/fisiopatologia , Auxiliares de Audição , Sistemas Microeletromecânicos , Humanos , Modelos Teóricos , Desenho de Prótese/métodos , Som , Transdutores
9.
Anal Chim Acta ; 1088: 1-19, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31623704

RESUMO

Application of the impedance spectroscopy technique to detection of bacteria has advanced considerably over the last decade. This is reflected by the large amount of publications focused on basic research and applications of impedance biosensors. Employment of modern technologies to significantly reduce dimension of impedimetric devices enable on-chip integration of interdigitated electrode arrays for low-cost and easy-to-use sensors. This review is focused on publications dealing with interdigitated electrodes as a transducer unit and different bacteria detection systems using these devices. The first part of the review deals with the impedance technique principles, paying special attention to the use of interdigitated electrodes, while the main part of this work is focused on applications ranging from bacterial growth monitoring to label-free specific bacteria detection.


Assuntos
Bactérias/isolamento & purificação , Microbiologia/instrumentação , Transdutores , Impedância Elétrica , Eletrodos , Humanos
10.
Zhongguo Yi Liao Qi Xie Za Zhi ; 43(5): 313-317, 2019 Sep 30.
Artigo em Chinês | MEDLINE | ID: mdl-31625324

RESUMO

The ultrasound endoscopic probes with very small size transducers are normally imaging by focused ultrasound beamforming technology. So the imaging frame rate is not very high, which cannot meet the needs of some clinical applications based on high imaging rate. In recent years, plane-wave ultrafast imaging technology can obtain high image frame rate and guarantee the image quality. In this paper, a plane wave ultra-fast imaging technique based on a home-made small line array ultrasound transducer is presented. Feasibility of the method is verified by simulation estimations and phantom experiments. The results show that for the small size transducer design of plane wave ultrafast imaging, it is necessary to fully consider the combination of the array element width and the number of array elements. So that a good plane wave imaging quality can be obtained. It lays a foundation for the ultra-fast imaging of plane wave in the interventional ultrasound imaging and ultrasound endoscopy.


Assuntos
Transdutores , Ultrassonografia , Imagens de Fantasmas , Ultrassonografia/instrumentação
11.
Nat Commun ; 10(1): 4405, 2019 09 27.
Artigo em Inglês | MEDLINE | ID: mdl-31562319

RESUMO

The emergence of smart electronics, human friendly robotics and supplemented or virtual reality demands electronic skins with both tactile and touchless perceptions for the manipulation of real and virtual objects. Here, we realize bifunctional electronic skins equipped with a compliant magnetic microelectromechanical system able to transduce both tactile-via mechanical pressure-and touchless-via magnetic fields-stimulations simultaneously. The magnetic microelectromechanical system separates electric signals from tactile and touchless interactions into two different regions, allowing the electronic skins to unambiguously distinguish the two modes in real time. Besides, its inherent magnetic specificity overcomes the interference from non-relevant objects and enables signal-programmable interactions. Ultimately, the magnetic microelectromechanical system enables complex interplay with physical objects enhanced with virtual content data in augmented reality, robotics, and medical applications.


Assuntos
Fenômenos Fisiológicos da Pele , Percepção do Tato/fisiologia , Tato , Dispositivos Eletrônicos Vestíveis , Algoritmos , Eletricidade , Fenômenos Eletromagnéticos , Eletrônica/instrumentação , Eletrônica/métodos , Humanos , Magnetismo , Robótica , Transdutores
12.
Sensors (Basel) ; 19(18)2019 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-31514319

RESUMO

Innovative monitoring systems based on sensor signals have emerged in recent years in view of their potential for diagnosing machining process conditions. In this context, preliminary applications of fast-response and low-cost piezoelectric diaphragms (PZT) have recently emerged in the grinding monitoring field. However, there is a lack of application regarding the grinding of ceramic materials. Thus, this work presents an analysis of the feasibility of using the acoustic emission signals obtained through the PZT diaphragm, together with digital signal processing in the time-frequency domain, in the monitoring of the surface quality of ceramic components during the surface grinding process. For comparative purpose, an acoustic emission (AE) sensor, commonly used in industry, was used as a baseline. The results obtained by the PZT diaphragm were similar to the results obtained using the AE sensor. The time-frequency analysis allowed to identify irregularities throughout the monitored process.


Assuntos
Acústica , Cerâmica/química , Transdutores , Processamento de Sinais Assistido por Computador , Propriedades de Superfície , Fatores de Tempo
13.
Ultrasonics ; 99: 105966, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31394481

RESUMO

The acoustic microscope is a powerful tool for the observation of biological matters. Non-invasive in-situ observation can be performed without any staining process. Acoustic microscopy is contrasted by elastic parameters like sound speed and acoustic impedance. We have proposed an acoustic microscope that can acquire three-dimensional acoustic impedance profile. The technique was applied to cell-size observation. Glial cells were cultured on a 70 µm-thick polypropylene film substrate. A highly focused ultrasound beam was transmitted from the rear side of the substrate, and the reflection was received by the same transducer. An acoustic pulse, its spectrum spreading briefly 100 through 450 MHz, was transmitted. By analyzing the internal reflections in the cell, the distribution of characteristic acoustic impedance along the beam direction was determined. Three-dimensional acoustic impedance mapping was realized by scanning the transducer, exhibiting the intra-cellular structure including nucleus and cytoskeleton.


Assuntos
Imagem Tridimensional , Microscopia Acústica/métodos , Neuroglia , Análise de Célula Única/métodos , Animais , Células Cultivadas , Impedância Elétrica , Ratos , Processamento de Sinais Assistido por Computador , Transdutores
14.
Ultrasonics ; 99: 105943, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31398497

RESUMO

The evaluation of the performance of nine physiotherapy ultrasound transducers used clinically was performed in the hospital environment using an acoustically absorbing thermocromic tile developed at the National Physical Laboratory (UK). The method consists of exposing an acoustic absorber tile, part of which contains a thermochromic pigment, to the ultrasonic beam, thereby forming an image of the intensity profile of the transducer. Images acquired using thermochromic materials were postprocessed in order to estimate effective radiating area (ERA) and beam nonuniformity ratio (BNR) for ultrasound transducers operating within the frequency range from 1.0 to 3.3 MHz, and nominal applied intensities in the range of 1-2W/cm2. Results of our measurements have shown that thermocromic tile can be used for quality control of ultrasound transducers in the hospital environment. Experimental results show that proposed method can be used to distinguish highly non - uniform ultrasound beams with high value of BNR. Influence of exposure duration on obtained ERA and BNR values was also analysed. Our results show that values for ERA increase with insonation time, while BNR values decrease. In order to compare our results with theory we have estimated temperature rise in thermochromic material experimentally and compare it with theoretical prediction.


Assuntos
Modalidades de Fisioterapia/instrumentação , Modalidades de Fisioterapia/normas , Terapia por Ultrassom/instrumentação , Terapia por Ultrassom/normas , Humanos , Teste de Materiais , Garantia da Qualidade dos Cuidados de Saúde , Transdutores
15.
Sensors (Basel) ; 19(15)2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31375011

RESUMO

Negative-capacitance shunted piezoelectric polymer was investigated in depth due to its considerable damping effect. This paper discusses the novel controlled stiffness performance from a rhombic piezoelectric stack transducer with three hybrid negative-impedance shunts, namely, negative capacitance in series with resistance, negative capacitance in parallel with resistance, and negative inductance/negative capacitance (NINC) in series with resistance. An analytical framework for establishing the model of the coupled system is presented. Piezoelectric shunt stiffness (PSS) and piezoelectric shunt damping (PSD) are proposed to analyze the stiffness and damping performances of the hybrid shunts. Theoretical analysis proves that the PSS can produce both positive and negative stiffness by changing the negative capacitance and adjustable resistance. The Routh-Hurwitz criterion and the root locus method are utilized to judge the stability of the three hybrid shunts. The results point out that the negative capacitance should be selected carefully to sustain the stability and to achieve the negative stiffness effect of the transducer. Furthermore, negative capacitance in parallel with resistance has a considerably better stiffness bandwidth and damping performance than the other two shunts. This study demonstrates a novel electrically controlled stiffness method for vibration control engineering.


Assuntos
Capacitância Elétrica , Impedância Elétrica , Polímeros/química , Vibração , Acústica , Modelos Teóricos , Transdutores
16.
Comput Methods Programs Biomed ; 179: 104982, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31443869

RESUMO

BACKGROUND AND OBJECTIVE: Transcranial focused ultrasound (tFUS) is a promising neuromodulation technique because of its non-invasiveness and high spatial resolution (within millimeter scale). However, the presence of the skull can lead to disrupting and shifting the acoustic focus in the brain. In this study, we propose a computationally efficient way to determine the optimal position of a single-element focused ultrasound transducer which can effectively deliver acoustic energy to the brain target. We hypothesized that the placement of a single element transducer with the lowest average reflection coefficient would be the optimal position. METHODS: The reflection coefficient is defined by the ratio of the amplitude of the reflected wave to the incident wave. To calculate the reflection coefficient, we assumed ultrasound waves as straight lines (beam lines). At each beam line, the reflection coefficient was calculated from the incidence angle at the skull interface (outer/inner skull surfaces). The average reflection coefficient (ARC) was calculated at each possible placement of the transducer using a custom-built software. For comparison purposes, acoustic simulations (k-Wave MATLAB toolbox) which numerically solved the linear wave equation were performed with the same transducer positions used in the ARC calculation. In addition, the experimental validation of our proposed method was also performed by measuring acoustic wave propagation through the calvaria skull phantom in water. The accuracy of our method was defined as the distance between the two optimal transducer placements which were determined from the acoustic simulations and from the ARC method. RESULT: Simulated acoustic pressure distribution corresponding to each ARC showed an inverse relationship with peak acoustic pressures produced in the brain. In comparison to the acoustic simulations, the accuracy of our method was 5.07 ± 4.27 mm when targeting the cortical region in the brain. The computing time of ARC calculations were 0.08% of the time required for acoustic pressure simulations. CONCLUSION: We calculated the ARC to find the optimal position of the tFUS transducer used in the present study. The optimal placement of the transducer was found when the ARC was the lowest. Our numerical and experimental results showed that the proposed ARC method can effectively be used to find the optimal position of a single-element tFUS transducer for targeting the cortex region of the brain in a computationally inexpensive way.


Assuntos
Crânio , Transdutores , Terapia por Ultrassom/instrumentação , Acústica/instrumentação , Encéfalo/anatomia & histologia , Simulação por Computador , Humanos , Imagem Tridimensional , Imagens de Fantasmas , Crânio/anatomia & histologia , Software , Terapia por Ultrassom/métodos , Terapia por Ultrassom/estatística & dados numéricos
17.
J Strength Cond Res ; 33(9): 2370-2380, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31460987

RESUMO

Chéry, C and Ruf, L. Reliability of the load-velocity relationship and validity of the PUSH to measure velocity in the deadlift. J Strength Cond Res 33(9): 2370-2380, 2019-This study investigated the reliability between load and mean velocity, mean propulsive velocity, peak velocity, mean power, and peak power in the deadlift. Also, we looked at the validity of an inertial sensor (PUSH) and a linear-position transducer (Tendo) to measure velocity variables. Ten strength-trained men (23.4 ± 1.3 years) were involved in three 1 repetition maximum (1RM) testing sessions, separated by at least 72 hours. The protocol used 6 different lifting intensities, comprising 20, 40, 60, 80, 90, and 100% of 1RM. Reliability of the load-velocity and load-power relationship was assessed by comparing velocity and power measurements from session 2 and 3 for each relative %1RM. The validity of tested devices was analyzed regarding to each relative intensity by comparing results from each instrument to a reference instrument (GymAware). The findings revealed that intermediate intensities (ranging from 60 to 90% of 1RM) seem to be reliable. Furthermore, extreme points of the load-velocity curve (20, 40, and 100% of 1RM) were found to be less reliable and should therefore be used with caution when implemented as part of autoregulating strategies. Tendo produced measurements that were highly correlated with GymAware and thus, constitutes a valid and cheaper alternative. By contrast, measurements from the PUSH presented a low level of precision and accuracy. Therefore, PUSH cannot be considered as a valid tool to measure velocity variables in the deadlift.


Assuntos
Treinamento de Resistência/métodos , Transdutores , Levantamento de Peso/fisiologia , Acelerometria/instrumentação , Humanos , Masculino , Conceitos Matemáticos , Força Muscular/fisiologia , Reprodutibilidade dos Testes , Adulto Jovem
18.
Sensors (Basel) ; 19(17)2019 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-31454907

RESUMO

Sound sensing finds wide applications in various fields, such as underwater detection, structural health monitoring, and medical diagnosis, to name just a few. Based on our previously developed MEMS-on-fiber sensors, showing the advantages of low cost, small volume, and high performance, a three-dimensional ultrasonic localization system employing four such sensors was established in this work. A time difference of arrival (TDOA) algorithm was utilized to analyze the acquired data and then calculate the accurate position of the ultrasonic signal source. Plenty of practical measurements were performed, and the derived localization deviation in the region of 2 m × 2 m × 1 m was about 2-5 mm. Outside this region, the deviation tended to increase due to the directional sensitivity existing in these sensors. As a result, for a more accurate localization requirement, more sensing probes are needed in order to depict a completely suitable application situation for MEMS technology.


Assuntos
Sistemas Microeletromecânicos/métodos , Som , Algoritmos , Humanos , Sistemas Microeletromecânicos/instrumentação , Transdutores , Ultrassom
19.
Ultrasonics ; 99: 105956, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31288119

RESUMO

The improvement of the micromachined ultrasound transducer based (CMUT) biosensor fabrication technology and signal processing, which led to higher signal to noise ratio is reported. The biosensor contains interdigitally arranged CMUT structure with gold-coated analytical area. It is assembled with the plexiglass microchannels. CMUTs were fabricated with the wafer bonding technology for 5 MHz operation in immersion. For signal processing the convolutional neural network (CNN) was developed and trained to classify the sensor data to different propagation delay values. For training of the network 750 thousand signals representing different properties of the bioanalyte and different noise conditions was simulated by the finite time difference domain (FDTD) model. The capability of the CNN algorithm to classify the propagation delay data was compared with the adaptive passband filter signal processing algorithm used in our previous version of the senor. Both sensing channels were run simultaneously with the reference liquids in the microchannel: deionized water switching to 0.9% saline. It was found that CNN channel is capable to improve the signal to noise ratio for this experiment to 75 dB, when the same property for the passband filter channel was only 60 dB. This led to the generalization about the advantage of CNN channel to provide 15 dB less of instrumental noise. Finally, the real-time detection ability of the bovine serum albumin (BSA) deposition on the analytical area of improved sensor was demonstrated.


Assuntos
Técnicas Biossensoriais , Processamento de Sinais Assistido por Computador , Ultrassom , Algoritmos , Animais , Bovinos , Desenho de Equipamento , Soroalbumina Bovina , Razão Sinal-Ruído , Transdutores
20.
Biosens Bioelectron ; 141: 111481, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31260904

RESUMO

Three-dimensional (3D) cell cultures developed with living cells and scaffolds have demonstrated outstanding potential for tissue engineering and regenerative medicine applications. However, no suitable tools are available to monitor dynamically variable cell behavior in such a complex microenvironment. In particular, simultaneously assessing cell behavior, cell secretion, and the general state of a 3D culture system is of a really challenging task. This paper presents our development of a dual-transduction-integrated biosensing system that assesses electrical impedance in conjunction with imaging techniques to simultaneously investigate the 3D cell-culture for bone regeneration. First, we created models to mimic the dynamic deposition of the extracellular matrix (ECM) in 3D culture, which underwent osteogenesis by incorporating different amounts of bone-ECM components (collagen, hydroxyapatite [HAp], and hyaluronic acid [HA]) into alginate-based hydrogels. The formed models were investigated by means of electrical impedance spectroscopy (EIS), with the results showing that the impedances increased linearly with collagen and hyaluronan, but changed in a more complex manner with HAp. Thereafter, we created two models that consisted of primary osteoblast cells (OBs), which expressed the enhanced green fluorescent protein (EGFP), and 4T1 cells, which secreted the EGFP-HA, in the alginate hydrogel. We found the capacitance (associated with impedance and measured by EIS) increased with the increases in initial embedded OBs, and also confirmed the cell proliferation over 3 days with the EGFP signal as monitored by the fluorescent imaging component in our system. Interestingly, the change in capacitance is found to be associated with OB migration following stimulation. Also, we show higher capacitance in 4T1 cells that secret HA when compared to control 4T1 cells after a 3-day culture. Taken together, we demonstrate that our biosensing system is able to investigate the dynamic process of 3D culture in a non-invasive and real-time manner.


Assuntos
Técnicas Biossensoriais/instrumentação , Regeneração Óssea , Técnicas de Cultura de Células/instrumentação , Animais , Linhagem Celular , Células Cultivadas , Colágeno/metabolismo , Durapatita/metabolismo , Impedância Elétrica , Desenho de Equipamento , Matriz Extracelular/metabolismo , Ácido Hialurônico/metabolismo , Camundongos , Osteoblastos/citologia , Osteoblastos/metabolismo , Tecidos Suporte/química , Transdutores
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