Solenoid

About: Solenoid is a research topic. Over the lifetime, 19278 publications have been published within this topic receiving 114721 citations.

Analytical Modeling and Optimization of Small Solenoid Coils for Millimeter-Sized Biomedical Implants

Abstract: The new trend towards minimally invasive millimeter-sized and free-floating distributed implants promises to enable emerging applications, such as chronic neural recording with minimal damage to the surrounding tissue. However, wireless power transmission (WPT) to these medical devices is quite challenging. The magnetic field produced by external transmitter (Tx) coils at the position of small implants can be considered homogeneous to separate the optimization of Tx and receiver (Rx) coils for efficient WPT. This paper focuses on the optimization of the solenoid-type Rx coils, which are suitable for this application. We have developed an analytical model of solenoid coils that includes the impact of tissue and coating around the coils, verified through simulations and measurements. Using the proposed model, under a given size restriction and a specific load, we find the optimal operating frequency and coil geometry to maximize a figure of merit (FoM) for the Rx that includes the loaded quality factor and its internal efficiency as well as a factor related to the coupling coefficient. For a millimeter-sized coil, the optimal operating frequency for the Rx and the number of turns are found to be 500 MHz and six, respectively, if the coil is closely wound using AWG36 copper wires. If the pitch is also optimized, then 700 MHz and four turns provide the best FoM for the solenoid Rx.

Homogeneous weak solenoids

Abstract: A (generalized) weak solenoid is an inverse limit space over manifolds with bonding maps that are covering maps. If the covering maps are regular, then we call the inverse limit space a strong solenoid. By a theorem of M.C. McCord, strong solenoids are homogeneous. We show conversely that homogeneous weak solenoids are topologically equivalent to strong solenoids. We also give an example of a weak solenoid that has simply connected path-components, but which is not homogeneous.

Barkhausen Noise Properties Measured by Different Methods for Deformed Armco Samples

Abstract: The main goal of this research is the comparison of Barkhausen effect (BN) properties evaluated by means of two different methods: 1) using a ?point probe? appropriate for industrial application; and 2) using a surrounding coil. The point probe contains ferrite core with searching coil perpendicular to the surface, and the sample is magnetized with a C-core electromagnet. Three quantities have been measured using first method: V1- rms voltage over many periods, Nc-number of BN pulses with amplitude higher than a given threshold, V2-maximal value of the flux derivative in the C-core. In the second method, the sample is magnetized with external solenoid and voltage signal induced in surrounding coil is analyzed providing several quantities: hysteresis loop of magnetic flux density, envelopes of BN rms voltage and pulse count rate over one period of magnetization, In-an integral of the rms envelope, N-total number of pulses, ? m-maximal value of differential permeability. The samples made from Armco iron sheet have been plastically deformed by tensile load at room temperature up to ? p =20%. The differences in BN properties revealed by these two methods are discussed qualitatively and explained.