Semiconducting metal oxide-based
gas sensors have inadequate selectivity
as they are responsive toward a variety of gases. Here, we report
the implementation of gas sensing kinetic analysis of the sensor to
identify the tested volatile organic compounds (VOCs) (2-propanol,
formaldehyde, methanol, and toluene) precisely. A single chemiresistive
sensor was employed having tin oxide-based hollow spheres as the sensing
material, which were obtained by chemical synthesis. The gas sensing
measurements were conducted in a dynamic manner where the sensor displayed
excellent response with high sensitivity. Eley–Rideal model
was adopted to obtain the kinetic properties of the gas sensing phenomenon
through theoretical fitting of response transient curves and their
corresponding kinetic parameters. The calculated characteristic kinetic
properties were further examined to discriminate among different VOCs.
The approach of using gas sensing kinetic analysis for multiple gas
discrimination is an attractive solution to mitigate the problem of
cross-sensitivity for resistive gas sensors.
Neuromodulation of peripheral nerves with bioelectronic devices is a promising approach for treating a wide range of disorders. Wireless powering could enable long-term operation of these devices, but achieving high performance for miniaturized and deeply placed devices remains a technological challenge. We report the miniaturized integration of a wireless powering system in soft neuromodulation device (15 mm length, 2.7 mm diameter) and demonstrate high performance (about 10%) during in vivo wireless stimulation of the vagus nerve in a porcine animal model. The increased performance is enabled by the generation of a focused and circularly polarized field that enhances efficiency and provides immunity to polarization misalignment. These performance characteristics establish the clinical potential of wireless powering for emerging therapies based on neuromodulation.
Myelination is governed by neuron-glia communication, which in turn is modulated by neural activity. The exact mechanisms remain elusive. We developed a novel in vitro optogenetic stimulation platform that facilitates subcellular activity induction in hundreds of neurons simultaneously. The light isolation was achieved by creating a biocompatible, light-absorbent, black microfluidic device integrated with a programmable, high-power LED array. The system was applied to a compartmentalized culture of primary neurons whose distal axons were interacting with oligodendrocyte precursor cells. Neural activity was induced along whole neurons or was constrained to cell bodies with proximal axons or distal axons only. All three modes of stimulation promoted oligodendrocyte differentiation and the myelination of axons as evidenced by a decrease in the number of oligodendrocyte precursor cells followed by increases in the number of mature oligodendrocytes and myelin sheath fragments. These results demonstrated the potential of our novel optogenetic stimulation system for the global and focal induction of neural activity in vitro for studying axon myelination.
Neural stimulation using injected electrical charge is widely used both in functional therapies and as an experimental tool for neuroscience applications. Electrical pulses can induce excitation of targeted neural pathways that aid in the treatment of neural disorders or dysfunction of the central and peripheral nervous system. In this review, we summarize the recent trends in the field of electrical stimulation for therapeutic interventions of nervous system disorders, such as for the restoration of brain, eye, ear, spinal cord, nerve and muscle function. Neural prosthetic applications are discussed, and functional electrical stimulation parameters for treating such disorders are reviewed. Important considerations for implantable packaging and enhancing device reliability are also discussed. Neural stimulators are expected to play a profound role in implantable neural devices that treat disorders and help restore functions in injured or disabled nervous system.
Abstract-We demonstrate a novel photoplastic nanoelectromechanical device that includes an encapsulated polysilicon piezoresistor. The temperature limitation that typically prevents deposition of polysilicon films on polymers was overcome by employing a hotwire CVD process. In this paper, we report the use of this process to fabricate and characterize a novel polymeric cantilever with an embedded piezoresistor. This device exploits the low Young's modulus of organic polymers and the high gauge factor of polysilicon. The fabricated device fits into the cantilever holder of an atomic force microscope (AFM) and can be used in conjunction with the AFM's liquid cell for detecting the adsorption of biochemicals. It enables differential measurement while preventing biochemicals from interfering with measurements using the piezoresistor. The mechanical and electromechanical characterization of the device is also reported in this paper.
[2008-0108]Index Terms-Affinity cantilevers, bio-microelectromechanical system (bio-MEMS), hotwire CVD (HWCVD), piezoresistive sensing, polymeric cantilevers, surface stress.
Electrical stimulations of neuronal structures must ensure net injected charges to be zero for biological safety and voltage compliance reasons. We present a novel architecture of general purpose biphasic constant current stimulator that exhibits less than 5.6 fC error while injecting 140 nC charges using 1.4 mA currents. The floating current sources and conveyor switch based system can operate in monopolar or bipolar modes. Anodic-first or cathodic-first pulses with optional inter-phase delays have been demonstrated with zero quiescent current requirements at the analog front-end. The architecture eliminates blocking capacitors, electrode shorting and complex feedbacks. Bench-top and in-vivo measurement results have been presented with emulated electrode impedances (resistor-capacitor network), Ag-AgCl electrodes in saline and in-vivo (acute) peripheral nerve stimulations in anesthetized rats.
Image Registration is the process of aligning two or more images of the same scene with reference to a particular image. The images are captured from various sensors at different times and at multiple view-points. Thus to get a better picture of any change of a scene/object over a considerable period of time image registration is important. Image registration finds application in medical sciences, remote sensing and in computer vision. This paper presents a detailed review of several approaches which are classified accordingly along with their contributions and drawbacks. The main steps of an image registration procedure are also discussed. Different performance measures are presented that determine the registration quality and accuracy. The scope for the future research are presented as well.
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