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The initial motivation for this work was to accomplish an easy way to manufacture different geometries of ultrasonic transducers and arrays using a PZT powder, combined with a standard process to have repetitive series of them. The piezoelectric thick film was obtained using a PZT paste and applying it by screen printing on an alumina substrate. Then, the film was drying and sintered with a temperature-time...
The development of a cell based biochip-sensing platform that examines the effects of toxic chemicals both electrically and optically is presented. The name of this sensing platform is called Toxichip. Toxichip aims to develop and promote alternative novel in-vitro testing methods for the monitoring of a vast array of toxins, thus alleviating the current demand for animal sacrifice while also permitting...
Recent attempts at estimating the parameters for respiratory impedance models from data obtained by Impulse Oscillometry (IOS) have come across difficulties when using the well-established Mead's model of human respiratory impedance. Unconstrained optimization of this model often yields values of chest wall compliance (CW) and lung compliance (Cl) too large to be physiologically feasible. We hypothesize...
This paper presents contributions on respiratory impedance and its phase constancy effects at high frequencies; i.e. 7.5-247.5 Hz. Measurements of 14 healthy volunteers are used to provide the input impedance values. It is shown, via the modulus-phase characteristics, that the impedance poses a typical frequency-independent behavior, known as phase constancy. We propose an electrical ladder network...
Biomedical signals are customarily overlaid with interferences and noise, furthermore, baseline wandering is another significant drawback to their accurate interpretation, especially if the implementation platform is a wheelchair. The nonlinear processes which generate the physiologic signals, and the disturbances, regularly exclude, or limit, the usage of classical linear techniques, hence, among...
Systolic time intervals (STI) have shown significant diagnostic and prognostic value to assess the global cardiac function. Their value has been largely established in hospital settings. Currently, STI are considered a promising tool for long-term patient follow-up with chronic cardiovascular diseases. Several technologies exist that enable beat-by-beat assessment of STI in personal health application...
Bio-recognition devices have captured special attention because they combine biological specificity and selectivity with electronics to perform environmental and biomedical analysis. Lindane is a recalcitrant pesticide considered potential carcinogen that has caused serious pollution problems. The purpose of the present study is to evaluate Streptomyces sp. M7 ability to dechlorinate lindane in liquid...
Radio frequency identification technology is used to power a novel platform of sensor devices. The employed energy harvesting system of the individual sensors enables a blanking of the radio frequency field for a defined period, while supplying the sensor electronics with a highly stable voltage. This guarantees interference free operation of the electronic circuitry during measurements. The implementation...
Here we present a new technique to monitor dynamic conformational changes in voltage-sensitive membrane-bound proteins using radio frequency (RF) impedance measurements. Xenopus oocytes were transfected to express ShakerB-IR K+ ion channels, and step changes in membrane potential were applied using two-electrode voltage clamp (TEVC). Simultaneously, bipolar extracellular electrodes were used to measure...
This paper reports a fabrication method for producing piezoelectric poly (vinylidene fluoride) films in their electroactive β-phase that features controlled thickness, smooth and flat surface, and high transparency. These piezoelectric films are suitable for being used as integrated microactuators, such as piezoelectric pumps and/or mixers, in microfluidic applications. Their actuation circuit design...
The aim of this study is to develop a method for measuring the respiratory waveform using non-contact electrodes during bathing. To determine the most appropriate electrode arrangement, we modeled a composite system consisting of a body submerged in bath water. We calculated the frequency dependence of the impedance amplitude using a three-dimensional finite difference method (3D-FDM). The simulation...
Gastric impedance spectroscopy has been proposed as a method of monitoring mucosal injury due to hypoperfusion and ischemia in the critically ill. During validation tests for this procedure, it was found that 60% of the measurements had errors by factors inherent to the clinical setting, indicating that some kind of automatic error detection should be incorporated to potentially avoid the loss of...
A new drip infusion solution monitoring system has been developed for hospital and care facility use. The system detects the fall of each drip chamber drop of fluid and also a free-flow situation. Three non-contacting copper foil electrodes are used. The electrodes are wrapped around the infusion supply polyvinyl chloride (PVC) tube from the solution bag, the drip chamber, and the infusion PVC tube...
For the reduction of common-mode noise level in Indirect-contact ECG (IDC-ECG) measurement, a driven-right-leg grounding method was applied to the IDC-ECG. Because the IDC-ECG does not require any direct contact between the electrodes and the human skin, it is adequate for un-constraining long-term ECG measurement at home and its various applications are now under development. However, larger 60 Hz...
Radiofrequency (RF) ablation uses RF current to heat and kill cancer applied via an electrode inserted under image-guidance, and is in clinical use for tumors in liver, lung kidney, and bone. Mathematical models are frequently used to determine tissue temperature during RF ablation, but most prior models do not include accurate implementation of power control algorithms as are used in clinical devices...
Tuning the electrode impedance through the DC biasing of iridium oxide is presented. Impedance reduction of up to two orders of magnitude was reproducibly observed in 20 μm diameter microelectrodes at a biasing of 1 V.
In many medical applications a well-directed positioning of a cannula in body tissue is mandatory. Especially the accurate placing of the cannula tip in the tissue is important for efficient drug delivery or for accessing blood vessels and nerves. This paper presents a new approach for a universal cannula navigation system based on tissue classification on the cannula tip by impedance spectroscopy...
Epilepsy affects nearly 3 million people in the United States alone. Given the fact that many people suffer from seizures that are intractable to pharmacological intervention, research groups are investigating the use of electrical stimulation to interact with and ameliorate symptoms of epileptic seizures. In mouse cortical slices made seizuregenic through chemical means, we applied precision controlled...
We describe our real-time, label-free, electrochemical impedance biosensor system with an emphasis on the use of an impedance response signal model to quantify assays. The signal processing for estimating model parameters from noisy data and the quantitative verification against target concentration and affinity are also presented.
Electrical Impedance Tomography (EIT) calculates the internal conductivity distribution within a body using electrical contact measurements. Conventional EIT reconstruction methods solve a linear model by minimizing the least squares error, i.e., the Euclidian or L2-norm, with regularization. Compressed sensing provides unique advantages in Magnetic Resonance Imaging (MRI) when the images are transformed...
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