Electrical stimulation of excitable tissue: design of efficacious and safe protocols.

The QRS complex is the most striking waveform within the electrocardiogram (ECG). Since it reflects the electrical activity within the heart during the ventricular contraction, the time of its occurrence as well as its shape provide much information about the current state of the heart. Due to its characteristic shape it serves as the basis for the automated determination of the heart rate, as an entry point for classification schemes of the cardiac cycle, and often it is also used in ECG data compression algorithms. In that sense, QRS detection provides the fundamentals for almost all automated ECG analysis algorithms. Software QRS detection has been a research topic for more than 30 years. The evolution of these algorithms clearly reflects the great advances in computer technology. Within the last decade many new approaches to QRS detection have been proposed; for example, algorithms from the field of artificial neural networks genetic algorithms wavelet transforms, filter banks as well as heuristic methods mostly based on nonlinear transforms. The authors provide an overview of these recent developments as well as of formerly proposed algorithms.

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The principles of software QRS detection

A haptic feedback planar touch control used to provide input to a computer. A touch input device includes a planar touch surface that inputs a position signal to a processor of the computer based on a location of user contact on the touch surface. The computer can position a cursor in a displayed graphical environment based at least in part on the position signal, or perform a different function. At least one actuator is also coupled to the touch input device and outputs a force to provide a haptic sensation to the user contacting the touch surface. The touch input device can be a touchpad separate from the computer's display screen, or can be a touch screen. Output haptic sensations on the touch input device can include pulses, vibrations, and spatial textures. The touch input device can include multiple different regions to control different computer functions.

Haptic feedback for touchpads and other touch control

http://www.ccs.fau.edu/%7Ebressler/EEGCCSBS/ferree2001.pdf

Scalp electrode impedance, infection risk, and EEG data quality

Thin-film electronics in its myriad forms has underpinned much of the technological innovation in the fields of displays, sensors, and energy conversion over the past four decades. This technology also forms the basis of flexible electronics. Here we review the current status of flexible electronics and attempt to predict the future promise of these pervading technologies in healthcare, environmental monitoring, displays and human-machine interactivity, energy conversion, management and storage, and communication and wireless networks.

Flexible Electronics: The Next Ubiquitous Platform

Sensory substitution systems provide their users with environmental information through a human sensory channel (eye, ear, or skin) different from that normally used or with the information processed in some useful way. The authors review the methods used to present visual, auditory, and modified tactile information to the skin and discuss present and potential future applications of sensory substitution, including tactile vision substitution (TVS), tactile auditory substitution, and remote tactile sensing or feedback (teletouch). The relevant sensory physiology of the skin, including the mechanisms of normal touch and the mechanisms and sensations associated with electrical stimulation of the skin using surface electrodes (electrotactile, or electrocutaneous, stimulation), is reviewed. The information-processing ability of the tactile sense and its relevance to sensory substitution is briefly summarized. The limitations of current tactile display technologies are discussed, and areas requiring further research for sensory substitution systems to become more practical are suggested. >

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Electrotactile and vibrotactile displays for sensory substitution systems

An idealized model for a circular electrosurgical dispersive electrode is analyzed by solving Laplace's equation for the potential distribution. The resulting analytical solution shows the origin of the perimetrical burn problem, and, simultaneously, points the way toward improved electrode designs. One possible improved electrode design, a segmented circular electrode in which the annular segments are connected to the RF generator through a series of current-leveling resistors, is proposed and discussed. Extensions of this concept and future areas for research are also discussed.

/pdf/analysis-and-control-of-the-current-distribution-under-3u63afce93.pdf

Analysis and Control of the Current Distribution under Circular Dispersive Electrodes

We report a novel coaxial antenna for hepatic microwave ablation. This device uses a floating sleeve, that is, a metal conductor electrically isolated from the outer connector of the antenna coaxial body, to achieve a highly localized specific absorption rate pattern that is independent of insertion depth. This floating sleeve coaxial dipole antenna has low power reflection in the 2.4-GHz IMS band. Ex vivo experiments confirm our numerical simulation results.

/pdf/a-floating-sleeve-antenna-yields-localized-hepatic-microwave-3moh3ptxj2.pdf

A floating sleeve antenna yields localized hepatic microwave ablation

Presents a silicon-based force sensor packaged in a flexible package and describes the sensors performance on human subjects. The sensing element consists of a circular silicon diaphragm (200-/spl mu/m thick with a 2-mm radius) over a 10-/spl mu/m sealed cavity with a solid Torlon dome providing force-to-pressure transduction to the diaphragm. Two dome heights (0.5 and 1.5 mm) were compared. The sensor with the taller dome showed improved sensitivity. Dynamic calibration and tracking experiments are performed with the sensor mounted on the dominant thumb of 5 human subjects. Both force and loading direction are statistically significant (P<0.05). Subject variability accounted for 8.7% of the variance, while loading direction accounted for 1.9% of the variance. Average errors for the tracking experiment range from -2.8 to 1.0 N and are subject dependent. Three out of 4 subjects showed increasing negative error with increasing load.

/pdf/a-silicon-based-tactile-sensor-for-finger-mounted-44u66wpbls.pdf

A silicon-based tactile sensor for finger-mounted applications

The use of electrical impedance tomography (EIT) imaging techniques in the measurement of lung resistivity for detection and monitoring of apnea and edema is proposed. In EIT, currents are injected into a subject using multiple electrodes, and boundary voltages are measured to reconstruct a cross-sectional image of internal resistivity distribution. It is found that a simplified, therefore fast, version of the impedance imaging method can be used for detection and monitoring of apnea and edema. The feasibility of this method has been shown through computer simulations and human experiments. The authors speculate that the EIT imaging technique will be more reliable than the current impedance apnea monitoring method, since they are monitoring the change of internal lung resistivity. However, more study is required to verify that this method performs better in the presence of motion artifact than the conventional two-electrode impedance apnea monitoring method. >

/pdf/measuring-lung-resistivity-using-electrical-impedance-2b68bbaw96.pdf

J.G. Webster

Papers

Electrotactile and vibrotactile displays for sensory substitution systems

Analysis and Control of the Current Distribution under Circular Dispersive Electrodes

A floating sleeve antenna yields localized hepatic microwave ablation

A silicon-based tactile sensor for finger-mounted applications

Measuring lung resistivity using electrical impedance tomography