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A small, hermetic, wirelessly-controlled retinal prosthesis was developed for pre-clinical studies in Yucatan mini-pigs. The device was implanted on the outside of the eye in the orbit, and it received both power and data wirelessly from external sources. The prosthesis drove a sub-retinal thin-film array of sputtered iridium oxide stimulating electrodes. The implanted device included a hermetic titanium...
Epidural spinal cord stimulation (ESCS) combined with partial weight bearing therapy (PWBT) has been reported to facilitate recovery of functional walking for individuals after chronic incomplete spinal cord injury. This paper describes a low cost, fully implantable, advanced ESCS stimulator that can be manufactured in a research laboratory for use in small animals. The system is composed of four...
Among numerous magnetic resonance imaging (MRI) techniques, perfusion MRI provides insight into the passage of blood through the brain's vascular network non-invasively. Studying disease models and transgenic mice would intrinsically help understanding the underlying brain functions, cerebrovascular disease and brain disorders. This study evaluates the feasibility of performing continuous arterial...
Established and emerging molecular and cellular modalities, such as optical imaging and spectroscopy, offer new opportunities for assessing tissue pathophysiology in situ. A challenge with such applications is their limited tissue penetration and low sensitivity that can be addressed with trans-needle or trans-catheter access. In this work, we describe the use of an actuated manipulator to physically...
In this study, an electromagnetics-based inverse sensitivity mapping method is introduced for applications in high field MRI. Instead of using simplistic numerical approximations, the sensitivity of the radio-frequency coil was determined through a field approach by using iterative optimization. The current study is an extension to previous studies on the inverse method, which has restricted itself...
Split magnet systems for hybrid imaging, such as positron emission tomography-magnetic resonance imaging (PET-MRI) and Radiotherapy-MRI, require gradient coils designed with similar shapes as their corresponding main magnet. This introduces challenges in the gradient coil design of good performance and manufacturing. In this paper the effect of the gap size in shielded transverse split gradient coils...
This paper reports an approach to the physical design of the coils used in a dual inductive link to provide two-way wireless communication and power for a neural recording system. The design approach makes use of an analytic model of the link performance in terms of the physical parameters of the link, which allows physical parameters to be iterated on a computer rather than on the bench to find the...
For many emerging neural prosthesis designs that are powered by inductive coupling, their small physical size requires large current in the extracorporeal transmitter coil, and the Class-E power amplifier topology is often used for the transmitter design. Tuning of Class-E circuits for efficient operation is difficult and a self-tuned circuit can facilitate the tuning. The coil current is sensed and...
We present a numerical investigation of the RF fields generated inside a human head by single and dual-row loop arrays. For a uniform circular polarization (CP) mode excitation, a dual-row array has no advantage for human brain excitation. Significant improvement of B1+ homogeneity with a simultaneous increase of coverage in the axial direction can be obtained by using a dual-row array together with...
Combining single coils to form a coil array provide advantages for magnetic induction measurements of breathing or heart activity. The main goal for such combination could be a coil configuration which makes the whole measurement system less sensitive for moving artifacts of the patient due to the capability of using many coils for signal acquisition. Such setup could be designed and tested with FEM...
This paper presents in vivo experimental results for a closed loop wireless power transmission system to implantable devices on an awake behaving animal subject. In this system, wireless power transmission takes place across an inductive link, controlled by a commercial off-the-shelf (COTS) radio frequency identification (RFID) transceiver (TRF7960) operating at 13.56 MHz. Induced voltage on the implantable...
We report on the development of a novel system that enables the wireless transmission of high-bandwidth physiological data from a freely moving mouse. The system employs inductive power transfer (IPT) to continuously power a battery-less transmitter using an array of overlapping planar coils placed under the animal. This arrangement provides a minimum of 20mW at all locations and orientations across...
Printed Spiral Coil (PSC) is a coil antenna for near-field wireless power transmission to the next generation implant medical devices. PSC for implant medical device should be power efficient and low electromagnetic radiation to human tissues. We utilized a physical model of printed spiral coil and applied our algorithm to design PSC operating at 13.56 MHz. Numerical and electromagnetic simulation...
In this paper, we formulate the parallel magnetic resonance imaging(pMRI) as a multichannel blind deconvolution problem with subsampling. First, the model allows formal characterization of image solutions consistent with data obtained by uniform subsampling of k-space. Second, the model allows analysis of the minimum set of required calibration data. Third, the filter bank formulation provides analysis...
A shielded, non-overlapped 9.4T 8-element transceive volume array was designed and constructed for small animal MRI studies. The coil configuration was optimized to obtain an appropriate trade-off between coil sensitivity, field penetration, and mutual decoupling. The simulated and experimental results presented herein demonstrate that the new volume array is capable of offering higher RF penetration,...
Telemetric sensing has received a great deal of attention in noncontact human disease detection. To take advantage of this method, this paper presents a SU-8-based compact (1.52 mm × 3.23 mm × 0.2 mm) passive wireless pressure sensor, especially designed to measure the intraocular pressure. The sensor was microfabricated using biocompatible materials such as gold and SU-8 [1] to form the LC parallel...
Three dimensional spatial selective RF pulse of practical length has been demonstrated using parallel transmission technique in Magnetic Resonance Imaging. Currently, spoke trajectory, which is a set of parallel k-space straight lines, is widely used for 3-D slab excitation to achieve sharp slice profile and a uniform or smoothly varying in-plane profile. The better control of in-plane profile mainly...
The development of compact magnetic stimulators will enable us to treat some intractable neurological diseases at one's home. In this study, we propose eccentric spiral coils which induce sufficient eddy currents in the brain at lower driving currents for the stimulator circuit. Numerical simulations based on the finite element method showed the advantages of the proposed design. A prototype coil...
Blinded studies with transcranial magnetic stimulation (TMS) require a valid sham condition. A wide range of sham approaches have been implemented but they have various limitations including residual electric field in the brain, inadequate reproduction of auditory and cutaneous sensations, and/or need for electrical stimulation with scalp electrodes. We propose a quadrupole TMS coil configuration...
This paper presents the preliminary results of a study to determine dorsolateral prefrontal cortex sensitivity to rTMS stimulation presented at clinically accepted amplitudes, frequencies and locations. A specially developed EEG system with 10–20 electrode locations was used to record the short latency magnetically evoked potentials. Sixteen normal subjects were stimulated using 10 Hz for the left...
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