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In its main definition, piezoelectrets are polymeric structures with electric charged internal cavities. The bipolar-trapped charges form macro-dipoles that can be mechanically deformed, thus presenting a high piezoelectric coefficient in the order of hundreds of pC/N. Such results outperform most of the traditional piezoelectric polymers. As piezoelectrets can be manufactured by different methods, some of the techniques allow the inner cavities to be geometrically controlled, therefore providing some degree of freedom in the piezoelectric behavior. This report provides a description of the most relevant methods, starting with a brief introduction of piezoelectret origin and reaching recent achievements in piezoelectret production, such as additive manufacturing (3D printing). Materials that are frequently employed in piezoelectret fabrication and methods for improving their characteristics are also presented.

The imagiology using Narrow Band Light (NBL) is widely employed in detection of mucosa's premature changes of gastrointestinal tract, while taking advantage of light spectral features by enhancing the vascular structures without the application of any type of dye. NBL uses two specific spectral bands centered in blue (415 nm) and green (540 nm). Despite their greater advantages, this technique is not available on intra-corporal imagiology devices yet. Thus, this paper presents a low-cost method to adapt such devices without the need to develop specific and expensive LEDs (Light-Emitting Diodes) centered at 415 nm and 540 nm. The method combines optical filters with commercial LEDs to provide transmitted light with the desired peaks at 415 nm and 540 nm. Two optical filters were designed and fabricated, using 7 thin-films layers of SiO2 and TiO2 deposited by RF sputtering. The measurements showed that the transmitted light through the filters presented relative transmittance peaks located at 414 nm and 542 nm wavelengths with relative transmittances of 31% and 62% and FWHM (Full-Width-Half-Maximum) of 17 nm and 29 nm, respectively. The measurements also showed significant relative transmittances located at NBL central wavelengths of 415 and 540 nm with 30% and 60%.

The design of solid-state materials whose properties and functions can be manipulated in a controlled manner by the application of electron beam irradiation is important in modern materials chemistry and physics. In this paper, we present a progress in the development of scalable electron beam irradiation platform to obtain innovative materials for technological and industrial applications, since one of the problems to be solved in this research area is the scalability of these new nanomaterials induced by electron beam irradiation (EBI). In particular, we focus on carbon structures due to its excellent and exciting properties applied in the technological area in the last years, where we show for the first time a new strategy for carbon allotropic transformation through the portable EBI. This new platform is particularly effective, fast, versatile, clean and easy-to-use, facilitating the preparation of many types of nanomaterials that cannot be obtained by conventional chemical and physical methods. The EBI on flat graphite pellets resulted in a covering of it surface with rod-like particles composed of different allotropic forms of carbon. Furthermore, the developed system allowed the implantation of the Fe as a catalytic material through steel sputtering of the high voltage acceleration anode during the EBI process. It was observed by HRTEM analyses that the rod-like particles are preferentially composed of highly oriented graphite in its bottom, polycrystalline graphite in its middle and magnetite nanoparticles in its top.

This study demonstrates that the electron beam irradiation of materials, typically used in characterization measurements, could be employed for advanced fabrication, modification, and functionalization of composites. We developed irradiation equipment using an electron beam irradiation source to be applied in materials modification. Using this equipment, the formation of a thick Ag film on the Ag3PO4 semiconductor is carried out by electron beam irradiation for the first time. This is confirmed by various experimental techniques (X-ray diffraction, field-emission scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy) and ab initio molecular dynamics simulations. Our calculations demonstrate that, at the earlier stages, metallic Ag growth is initiated preferentially at the (110) surface, with the reduction of surface Ag cations forming metallic Ag clusters. As the (100) and (111) surfaces have smaller numbers of exposed Ag cations, the reductions on these surfaces are slower and are accompanied by the formation of O2 molecules.

In this paper, a microwave biosensor with unprecedented sensitivity based on encoded pulse propagation and microfluidics is theoretically investigated and experimentally demonstrated. The structure consists of a double-spiral transmission line on FR4 substrate electromagnetically coupled to a copper coiled capillary tube above it. The working principle for improved sensitivity consists of propagating an encoded sequence of short pulses (Walsh-Hadamard spreading code with variable temporal length) in a recirculating manner so that the pulses are deformed both due to dispersive and time-delay effects. Once the recirculation is finished, the energy of the code at the sensor output is calculated, providing an indicator directly related with the analyte concentration. The experimental results demonstrate the improved sensitivity of this sensor approach for the case of glucose with 2.9 mg/ml resolution. Furthermore, we demonstrate the potential of this technology as a sensor platform by investigating other chemical compounds such as isopropyl alcohol (IPA) and acetone with a sensitivity of 20% of the volume. Finally, the outstanding performance, both in terms of accuracy and sensitivity, situates the present multi-purpose approach within the state-of-the-art of microwave (bio)chemical sensors.

The non-invasive intracranial pressure (NIICP) method based on a skull deformation has been proven to be a significant tool for an assessment of the intracranial pressure (ICP) and compliance. Herein, we present the development and characterization of a novel wireless sensor that uses this method as its working principle and was designed to be easy to use, to have a high resolution, and to achieve a good accessibility. Initially, a brief review of the physiology fundamentals of the ICP and the historic evolution of the NIICP method are mentioned. The sensor architecture and the rationale for the chosen components are then presented, aiming to ensure nanometer displacement measurements, the conversion of analog resolution to digital at a high speed, the fewest amount of distortion, wireless communication, and signal calibration. The NIICP signal has a typical amplitude of $5~\mu \text{m}$ , and thus a resolution of at least 1% of this amplitude is required for an NIICP waveform analysis. We also demonstrate a 40-nm resolution of the sensor using a nanometric displacement test system that can also respond dynamically for NIICP signals from 50 to 180 bpm without any significant distortion (maximum deviation of P2/P1 ratio of 2.6%). The future applications for this device are broad and can enhance a clinical assessment of the intracranial dynamics.

Electrical impedance spectroscopy has been used extensively for sensing and biosensing due to the multiple electrical properties that can be interrogated through varying the frequency of the electrical excitation. In this paper, we review the basic concepts and key issues for applying impedance spectroscopy in sensing and biosensing, with emphasis on the development of precise, low-cost and portable instruments. An impedance spectroscopy system can be divided into three parts: the signal processing unit, the sensing unit and the data analysis unit. Herein, we focus on the signal processing unit, responsible for generating the excitation signal and performing the impedance readout. Special attention is given to small and low-cost signal processing circuits, which are essential for portability and point-of-care diagnosis. We also elaborate upon the various methods to fabricate the sensing units, including the choice of nanomaterials and biomolecules in controlled molecular architectures. From an instrumentation perspective, we discuss possible sources of interference in the measurement protocols. When impedance spectroscopy measurements are performed with arrays of sensing units, as with electronic tongues, large amounts of data are generated. This has motivated an increasing use of statistical and computational methods for data analysis. We present some of these methods, with examples of information visualization and machine learning techniques, which have been employed in analyzing impedance spectroscopy data in recent years.

Photodynamic Therapy (PDT) is a technique used in the selective destruction of cancer cells and requires the previous knowledge of light dosimetry and photosensitizer drug (PS) concentration to apply on cells. Therefore, a laboratory platform is required for further evaluation, e.g. to make evaluation and assays on previously collected cells by biopsy to determine the best combination of light dose and PS concentration. In this context, this paper presents a low-cost, low-sized and flexible Wireless Portable Evaluation Platform for PDT assays on cells. The W-PEP was tested and evaluated using assays with Human Gastric Adenocarcinoma (AGS) cells. The AGS cells were exposed to the 5-aminolevulinic acid (ALA), which is a precursor of the photosensitive agent Protoporphyrin IX (PpIX) with absorption at 635nm. The W-PEP is composed by 16 small-sized LEDs matrix with peak transmittance at 634nm mounted in a PCB and controlled by ESP32-DevKitC®, a power bank to supply the lighting and the controlling systems and 3D printed components specially designed to allow portability and PDT assays. A graphical user interface (GUI) application for mobile devices was developed allowing the bi-directional communication between the smartphone and W-PEP via Bluetooth. The measurements with AGS cells proved this W-PEP was effective in its purpose and promoted cell death in samples treated with ALA and a final light dose of 5J/cm2 after 49 minutes of light exposure. This W-PEP has 140mm of both length and width, 75mm of height and costs about $82.10. To finish, this system checks the optimal conditions that will be applied in the treatment after, thereby decreasing the costs and time of the application.

This work focuses on acoustic analysis as a way of discriminating mineral oil, providing a robust technique, immune to electromagnetic noise, and in some cases, depending on the applied sensor, a low-cost technique. Thus, we propose a new method for the diagnosis of the quality of mineral oil used in electrical transformers, integrating a ferroelectric-based hydrophone and an acoustic transducer. Our classification solution is based on a supervised machine learning technique applied to the signals generated by an in-home built hydrophone. A total of three statistical datasets entries were collected during the acoustic experiments on four types of oils. The first, the second, and third datasets contain 180, 240, and 420 entries, respectively. Eighty-four features were considered from each dataset to apply to two classification approaches. The first classification approach is able to distinguish the oils from the four possible classes with a classification error less than 2%, while the second approach is able to successfully classify the oils without errors (e.g., with a score of 100%).

This work presents a capacitive modulator design and modeling of a new waveguide architecture using silicon and poly-si technologies. We use a methodology involving the entire lumped-type modulator design process, from the optical design to the small-signal RF analysis. By means of geometric and physical parameters adjustments, the trade-offs among several figures of merit are analyzed in this paper. Due to the waveguide configuration, it is shown that the modulator can improve the trade-off between $V_{\pi }$ and bandwidth compared to the state-of-the-art for this kind of device. For instance, the best combinations are $V_{\pi }\simeq$ 1 V @ 20.4 GHz and $V_{\pi }$ = 5.7 V @ $\sim$ 31 GHz, with equivalent optical losses of 3 dB and 1.1 dB, respectively.

The exponential demand for bandwidth in data centers is on high alert with the increase in data traffic. In this scenario, the design of optical modulators is crucial for the continuous evolution of communication systems. For data center interconnect (DCI) applications, this mean that modulators should offer high bandwidth and low optical loss. In addition, devices must operate with low power consumption and be compatible with complementary metal–oxide–semiconductor (CMOS) processes for low-cost and large-scale manufacturing. These facts show the importance of advancement in Silicon (Si) modulators solutions, since they have the potential to fulfill all these requirements. However, designing a device that meets all these requirements at the same time is still challenging, because there are several trade-offs problems involved for which different Silicon modulators types are not yet able to solve. In this context, this paper reviews the challenges in Silicon photonics (SiPh) modulators for data center interconnect applications.

A Silicon (Si) modulator and a design methodology using a system-oriented numerical approach are proposed. The main contributions of this work are to provide a Silicon modulator as an alternative solution for intra-data center interconnect (DCI) applications and a single figure-of-merit (FOM) for the modulator design, which takes as input the main device parameters (modulation efficiency ( V π × L ), optical loss, and electro-optical bandwidth ( f 3 d B )) and provides a global optical system optimization. By using a numerical approach, the modulator physical parameters are analyzed according to system performance metrics such as the required receiver sensitivity to reach a target bit error rate (BER), and the required transmitter launch power. A capacitive Silicon device and a 4-level pulse amplitude modulation (PAM-4) system simulator is presented. The results show an efficient modulator ( V π = 3.5 V ) with high bandwidth ( f 3 d B > 38 GHz ), which is promising for data centers solutions, where power consumption is critical and high-speed is required.

This paper presents a system for characterization of thermoelectric generators (TEGs) for energy harvesting. This system can monitor and characterize up to three TEGs simultaneously and it is comprised by two main electronic circuits: The first one is composed by twelve input channels being three for reading voltage, three for reading current by making use of instrumentation amplifiers (reference ACS712) and six thermocouples for signal reading (

A cápsula endoscópica é um instrumento revolucionário, que permite a realização de um exame livre de desconfortos para o paciente e possibilitou a técnica de endoscopia chegar a partes do sistema gastrointestinal que antes não era possível, como grande parte do intestino delgado. Este trabalho apresenta um módulo fotônico para realizar Terapia Fotodinâmica (PDT, Photodynamic Therapy) em cápsulas endoscópicas. A PDT é uma forma de tratamento para lesões que envolve a administração prévia de um medicamento fotossensível (PS, Photosensitizer) e posterior ativação com irradiação de luz em um comprimento de onda (λ) específico. Geralmente para a ativação do PS utiliza-se λ na região vermelha do espectro visível, pois a penetração nos tecidos é elevada. Células de adenocarcinoma gástrico humano (AGS, Adenocarcinoma Gastric of Stomach) foram preparadas com ácido 5-aminolevulínico (5-ALA) que é um Pró-fármaco precursor do agente fotossensível Protoporfirina IX (PpIX) com máximo de absorção nos 635 nm. Para realizar a irradiação com luz vermelha nas células, 16 LEDs do modelo LRQ396-P1Q2-1 da Osram Opto Semiconductors com dimensões muito reduzidas foram selecionados, caracterizados, montados em uma PCB (Printed Circuit Board) e alimentados por um Arduino Mega 2560. Este sistema de iluminação foi eficaz em seu propósito e causou morte celular nas células submetidas ao tratamento com o ALA em uma concentração de 2 milimol por litro e dose de luz em 5 Joules por centímetro quadrado que resulta em uma exposição de 49 minutos. Com o objetivo de se construir um módulo para controle de iluminação em cápsulas endoscópicas, foi desenvolvido em tecnologia CMOS 0.7 μm da ON Semiconductor um dispositivo capaz de controlar a intensidade dos LEDs utilizando PWM (Pulse Width Modulation). Unindo este componente com os LEDs selecionados é perfeitamente possível construir o módulo e inseri-lo CEs para realizar PDT em locais do trato gastrointestinal (GI) não acessíveis pela endoscopia convencional. The endoscopic capsule is a revolutionary instrument that gives a free examination of discomforts for patient and allows the endoscopic technique to reach parts of the gastrointestinal system that were previously not possible, such as a large part of the small intestine. This work presents a photonic module to perform Photodynamic Therapy (PDT) in endoscopic capsules. PDT is a form of treatment for injuries involving prior administration of a photosensitive drug (PS, Photosensitizer) and subsequent activation with light irradiation at a specific wavelength (λ). Usually for PS activation, λ is used in the red region of the visible spectrum, because the tissue penetration is high. Human gastric adenocarcinoma cells (AGS) were prepared with 5-aminolevulinic Acid (5-ALA) which is a Pro-drug precursor of the photosensitive agent Protoporphyrin IX (PpIX) with maximum absorption at 635 nm. To perform red light irradiation on the cells, 16 LEDs, model LRQ396-P1Q2-1 of the Osram Opto Semiconductors with very small dimensions were selected, characterized, mounted on a PCB (Printed Circuit Board) and powered by an Arduino Mega 2560. This system was effective in its purpose and caused cell death in cells treated with ALA at a concentration of 2 mMol/L and dose of light at 5 J/cm² resulting in a 49 minutes exposure. With the objective of build a module for control of lighting in endoscopic capsules, a device able to controlling the intensity of the LEDs using PWM (Pulse Width Modulation) was developed in CMOS technology 0.7 μm of the ON Semiconductor. Combining this component with the selected LEDs, it is perfectly possible to construct the module and insert in CEs to perform PDT at sites of the gastrointestinal tract (GI) not accessible by conventional endoscopy.

Several industrial applications require liquid characterization during manufacturing to ensure quality in their products. Examples of such products are those related to food and oil industries in which one of the concerns regards the different concentration of liquids in a mixture. In this context, it is presented a system based on ferroelectret transducers and low-cost technology to perform liquid analysis through acoustic measurements. The developed system is composed of three parts: a piezoelectric actuator, a medium chamber and a ferroelectret transducer (acoustic sensor). The system was assembled with a ferroelectret (with open tubular channels) housed on a cylindrical aluminum case (48 mm × 63 mm) in which a 24 dB preamplifier was mounted. The specifically designed chamber was manufactured in ABS plastic using a 3D printer and the piezoelectric actuator consisted in commercial piezoelectric ceramic which is connect to signal generator configured to generate a sinusoidal sweep between 0 Hz up to 50 kHz during 1 s. In order to characterize the device setup and validate the suitableness of the measuring system, three distinct mediums were analyzed (air, water and oil). Through the experimental tests it was identified, on time domain, distinct signatures for each medium, which were later used in a blind classification with a developed algorithm.

Made available in DSpace on 2020-12-12T01:42:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-11-15 This paper presents a portable laboratory platform (PLP) with electrochemical amperometric biosensors for the detection of hepatitis C virus (HCV). This PLP is composed by a controller unit, a Bluetooth module to provide communication with mobile devices, and a potentiostat circuit to perform cyclic voltammetry. The Bluetooth communication allows the mobile devices to set up the parameters, e.g., a cycling voltage in the range ±1.5 V, a scan rate in the range 5-1000 mV-1 with a step potential of 2.318 mV, and up to 4000 number of scan cycles. The electrochemical sensors were functionalized with cystamine (C4H12N2S2) and glutaraldehyde (C5H8O2) to make the covalent binding with the recombinant core-HCV protein. The experimental results have revealed a positive detection of HCV, using a redox solution of 5 mmol.L-1 of potassium ferrocyanide (K3 Fe(CN)6) on 0.1 mol.L-1 of phosphate-buffered saline (PBS). The sensitivity of the immunosensor was established at the concentration of 1 ng. μ L-1 of the anti-core-HCV IgG class antibody. This PLP has a plug-and-play connection for the biosensors, and at the same time, it offers good ergonomy with easy operation due to its low dimensions (115 mm × 75 mm × 30 mm). This PLP presents a power consumption of 280.5 mW when supplied with a 3.3-V voltage source. This consumption was measured in the worst operation case, e.g., with the Bluetooth working, resulting in an average battery life of 195 min. Department of Electrical Engineering (SEL) University of São Paulo (USP) Department of Chemistry INCTMN-CDMF Federal University of São Carlos (UFSCar) Department of Clinical Analysis School of Pharmaceutical Sciences Laboratory of Clinical Immunology and Molecular Biology (LICBM) São Paulo State University (UNESP) Institute of Chemistry São Paulo State University (UNESP) Department of Clinical Analysis School of Pharmaceutical Sciences Laboratory of Clinical Immunology and Molecular Biology (LICBM) São Paulo State University (UNESP) Institute of Chemistry São Paulo State University (UNESP)

This paper proposes a Flexible Infrastructure for Dynamic Power Control (FIDPC) of Electric Vehicle (EV) Battery Chargers. This infrastructure dynamically adjusts the EV battery charger current, according to the power demand of the home wherein the vehicle is plugged. An infrastructure was implemented to validate this proposal. Such infrastructure is composed by an EV battery charger and a communication system based on a Radio Frequency interface. The battery charger has nominal power of 3.6 kVA and operates with sinusoidal current and unitary total power factor, while the RF interface provides continuous data flow to the battery charger with information about the home total current consumption (rms value). Experimental tests were performed under realistic conditions to validate the concept behind the proposed FIDPC. These tests served to assess the behavior of the EV battery charger with dynamic power control on a single-phase, 230 V, 16 A, 50 Hz residential electrical installation. The experimental results confirm the quick time response of the FIDPC even when working under heavy home load variations., This work was supported by the Fundacao para a Ciencia e Tecnologia (FCT) through Project PEst-UID/CEC/00319/2013. The work of V. Monteiro was supported by the FCT agency through a doctoral scholarship under Grant SFRH/BD/80155/2011. The review of this paper was coordinated by Dr. D. Cao.

This paper presents a capacitive modulator design and modeling using poly-si and silicon technologies. We propose a methodology involving the entire modulator design process, from the optical design, charge distribution calculation and small-signal RF analysis. Thus, in the case of silicon photonics modulators, the paper proposes means to optimize the trade-offs among several figures of merit. It is shown that high bandwidth operation (>30 GHz) can be achieved by sacrificing a little the modulation efficiency. info:eu-repo/semantics/publishedVersion

Transformers are one of the most important equipment found in electrical power systems. Thus, their status must be constantly monitored to avoid critical failures. The analysis of the dissolved gas (DGA) in the oil is one of the most important technique to detect short-circuits and partial discharges. However, this technique has a serious drawback to get the percentage of water absorbed by the oil, requiring other kind of predictive technique. In this context, this paper presents a technique to detect the water content in oils, which uses ultrasound measurement. The measurement results showed that after the frequency scan, the best results for determining the percentage of water in insulating oils were obtained at frequencies around 5MHz. These preliminary results revealed very promising.