Design and Validation of Miniaturized Repetitive Transcranial Magnetic Stimulation (rTMS) Head Coils.

Repetitive transcranial magnetic stimulation (rTMS) is a rapidly developing therapeutic modality for the safe and effective treatment of neuropsychiatric disorders. However, clinical rTMS driving systems and head coils are large, heavy, and expensive, so miniaturized, affordable rTMS devices may facilitate treatment access for patients at home, in underserved areas, in field and mobile hospitals, on ships and submarines, and in space. The central component of a portable rTMS system is a miniaturized, lightweight coil.

A Compact Circuit for Boosting Electric Field Intensity in Repetitive Transcranial Magnetic Stimulation (rTMS).

The concept of a portable, wearable system for repetitive transcranial stimulation (rTMS) has attracted widespread attention, but significant power and field intensity requirements remain a key challenge. Here, a circuit topology is described that significantly increases induced electric field intensity over that attainable with similar current levels and coils in conventional rTMS systems. The resultant electric field is essentially monophasic, and has a controllable, shortened duration.

A Compact Battery-Powered rTMS Prototype.

This paper describes the design and testing of a compact, battery-powered repetitive Transcranial Magnetic Stimulation (rTMS) prototype. This device generates a 10 Hz magnetic pulse train with peak flux density of 100 mT at 2 cm distance. Circuit component design, including the inductor, switched LC resonator, and boost converter, are discussed in the context of weight and size reduction, and performance optimization.

Intrinsically Linear Transistor for Millimeter-Wave Low Noise Amplifiers.

Transistors are the backbone of any electronic and telecommunication system but all known transistors are intrinsically nonlinear introducing signal distortion. Here, we demonstrate a novel transistor with the best linearity achieved to date, attained by sequential turn-on of multiple channels composed of a planar top-gate and several trigate Fin field-effect transistors (FETs), using AlGaN/GaN structures. A highly linearized transconductance plateau of >6 V resulted in a record linearity figure of merit OIP3/P of 15.

A reusable microfluidic plate with alternate-choice architecture for assessing growth preference in tissue culture.

We present the design of a chamber to evaluate in vitro how species and concentrations of soluble molecules control features of cell growth-potentially including cell proliferation, cell motility, process extension, and process termination. We have created a reusable cell culture plate that integrates a microfluidic media delivery network with standard cell culture environment. The microfluidic network delivers a stream of cell culture media with a step-like concentration gradient down a 50-100 microm wide microchannel called the presentation region.