Vibration energy harvesting using piezoelectric transducer and non-controlled rectifiers circuits

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Characterization of the temperature, load and damage effects using piezoelectric transducer patches based on fuzzy clustering

Structural Health Monitoring (SHM) denotes a system with the ability to detect and interpret adverse changes in a structure. One of the critical challenges for practical implementation of SHM system is the ability to detect damage under changing environmental conditions. This paper aims to characterize the temperature, load and damage effects in the sensor measurements obtained with piezoelectric transducer (PZT) patches. Data sets are collected on thin aluminum specimens under different environmental conditions and artificially induced damage states. The fuzzy clustering algorithm is used to organize the sensor measurements into a set of clusters, which can attribute the variation in sensor data due to temperature, load or any induced damage.

Jacalin interaction with human immunoglobulin A1 and bovine immunoglobulin G1: Affinity constant determined by piezoelectric biosensoring

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of Excitation Signal on Impedance-based Structural Health Monitoring

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

High sensitivity fiber optic angular displacement sensor and its application for detection of ultrasound

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Sistema de extração de potência (power harvesting) usando transdutores piezelétricos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desenvolvimento e implementação de um sistema para detecção de falhas em estruturas usando microcontrolador

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Novas técnicas de detecção de fase óptica em interferômetros homódinos aplicadas à caracterização de atuadores piezoelétricos flextensionais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Leakage detection in water pipe networks using electromechanical impedance (EMI) based technique

The electromechanical impedance (EMI) technique has been successfully used in structural health monitoring (SHM) systems on a wide variety of structures. The basic concept of this technique is to monitor the structural integrity by exciting and sensing a piezoelectric transducer, usually a lead zirconate titanate (PZT) wafer bonded to the structure to be monitored and excited in a suitable frequency range. Because of the piezoelectric effect, there is a relationship between the mechanical impedance of the host structure, which is directly related to its integrity, and the electrical impedance of the PZT transducer, obtained by a ratio between the excitation and the sensing signals.This work presents a study on damage (leaks) detection using EMI based method. Tests were carried out in a rig water system built in a Hydraulic Laboratory for different leaks conditions in a metallic pipeline. Also, it was evaluated the influence of the PZT position bonded to the pipeline. The results show that leaks can effectively be detected using common metrics for damage detection such as RMSD and CCDM. Further, it was observed that the position of the PZT bonded to the pipes is an important variable and has to be controlled.

Transducer Loading Effect on the Performance of PZT-Based SHM Systems

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Piezoelectric transducers assessed by the pencil lead break for impedance-based structural health monitoring

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evaluating the equilibrium association constant between artinM lectin and myeloid leukemia cells by impedimetric and piezoelectric label free approaches

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ultrathin films of lignins as a potential transducer in sensing applications involving heavy metal ions

Lignins extracted from sugar cane bagasse using different alcohols in the organosolv-CO(2) supercritical pulping process have been applied in the fabrication of ultrathin films through the Langmuir-Blodgett technique. Langmuir films were characterized by surface pressure versus mean molecular area (Pi-A) isotherms to exploit the sensitivity of nanostructured lignin films to metallic ions (Cu(2+), Cd(2+) and Pb(2+)). The Pi-A isotherms were shifted to larger molecular areas when heavy metal ions are present into the subphase, which might be related to electrostatic repulsions between metallic ions entrapped within the lignin molecular structure. Taking the advantage of metal incorporation, Langmuir monolayers were transferred onto solid substrates forming Langmuir-Blodgett (LB) films to be used as a transducer in an "electronic tongue" system to detect Cu(2+) in aqueous solution below threshold standard established by the Brazilian regulation. Both techniques impedance spectroscopy and electrochemistry have been used in these experiments. Complementary, Fourier transform infrared (FTIR) spectroscopy recorded for LB films before and after soaking into Cu(2+) aqueous solution revealed an interaction between the lignin phenyl groups and the metallic ion. (C) 2007 Elsevier B.V.. All rights reserved.

Piezoelectric biosensors for real-time monitoring of hybridization and detection of hepatitis C virus

The piezoelectric quartz crystal resonators modified with oligonucleotide probes were used for detection of hepatitis C virus (HCV) in serum. The gold electrodes on either rough or smooth surface crystals were modified with a self-assembled monolayer of cystamine. After activation with glutaraldehyde, either avidin or streptavidin were immobilized and used for attachment of biotinylated DNA probes (four different sequences). Piezoelectric biosensors were used in a flow-through setup for direct monitoring of DNA resulting from the reverse transcriptase-linked polymerase chain reaction (RT-PCR) amplification of the original viral RNA. The samples of patients with hepatitis C were analyzed and the results were compared with the standard RT-PCR procedure (Amplicor test kit of Roche, microwell format with spectrophotometric evaluation). The piezoelectric hybridization assay was completed in 10 min and the same sensing surface was suitable for repeated use. (C) 2004 Elsevier B.V. All rights reserved.

Signal transducer and activator of transcription 3-regulated sarcoendoplasmic reticulurn Ca2+-ATPase 2 expression by prolactin and glucocorticoids is involved in the adaptation of insulin secretory response during the peripartum period

During pregnancy, the maternal endocrine pancreas undergoes, as a consequence of placental lactogens and prolactin (PR,L) action, functional changes that are characterized by increased glucose-induced insulin secretion. After delivery, the maternal endocrine pancreas rapidly returns to nonpregnant state, which is mainly attributed to the increased serum levels of glucocorticoids (GCs). Although GCs are known to decrease insulin secretion and counteract PRL action, the mechanisms for these effects are poorly understood. We have previously demonstrated that signal transducer and activator of transcription 3 (STAT3) is increased in islets treated with PRL. In the present study, we show that STAT3 expression and serine phosphorylation are increased in pancreatic islets at the end of pregnancy (P19). STAT3 serine phosphorylation rapidly returned to basal levels 3 days after delivery (U). The expression of the sarcoendoplasmic reticulum Ca2+-ATPase 2 (SERCA2), a crucial protein involved in the regulation of calcium handling in P-cells, was also increased in P19, returning to basal levels at L3. PRL increased SERCA2 and STAT3 expressions and STAT3 serine phosphorylation in RINm5F cells. The upregulation of SERCA2 by PRL was abolished after STAT3 knockdown. Moreover, PRL-induced STAT3 serine phosphorylation and SERCA2 expression were inhibited by dexamethasone (DEX). Insulin secretion from islets of PI 9 rats pre-incubated with thapsigargin and L3 rats showed a dramatic suppression of first phase of insulin release. The present results indicate that PRL regulates SERCA2 expression by a STAT3-dependent mechanism. PRL effect is counteracted by DEX and might contribute to the adaptation of maternal endocrine pancreas during the peripartum period.