Recent Advances in Neural Recording Microsystems

The accelerating pace of research in neuroscience has created a considerable demand for neural interfacing microsystems capable of monitoring the activity of large groups of neurons. These emerging tools have revealed a tremendous potential for the advancement of knowledge in brain research and for the development of useful clinical applications. They can extract the relevant control signals directly from the brain enabling individuals with severe disabilities to communicate their intentions to other devices, like computers or various prostheses. Such microsystems are self-contained devices composed of a neural probe attached with an integrated circuit for extracting neural signals from multiple channels, and transferring the data outside the body. The greatest challenge facing development of such emerging devices into viable clinical systems involves addressing their small form factor and low-power consumption constraints, while providing superior resolution. In this paper, we survey the recent progress in the design and the implementation of multi-channel neural recording Microsystems, with particular emphasis on the design of recording and telemetry electronics. An overview of the numerous neural signal modalities is given and the existing microsystem topologies are covered. We present energy-efficient sensory circuits to retrieve weak signals from neural probes and we compare them. We cover data management and smart power scheduling approaches, and we review advances in low-power telemetry. Finally, we conclude by summarizing the remaining challenges and by highlighting the emerging trends in the field

A multiband inductive wireless link for implantable medical devices and small freely behaving animal subjects

The objective of this research is to introduce two state-of-the-art wireless biomedical systems: (1) a multiband transcutaneous communication system for implantable microelectronic devices (IMDs) and (2) a new wireless power delivery system, called the “EnerCage,” for experiments involving freely-behaving animals. The wireless multiband link for IMDs achieves power transmission via a pair of coils designed for maximum coupling efficiency. The data link is able to handle large communication bandwidth with minimum interference from the power-carrier thanks to its optimized geometry. Wireless data and power links have promising prospects for use in biomedical devices such as biosensors, neural recording, and neural stimulation devices. The EnerCage system includes a stationary unit with an array of coils for inductive power transmission and three-dimensional magnetic sensors for non-line-of-sight tracking of animal subjects. It aims to energize novel biological data-acquisition and stimulation instruments for long-term experiments, without interruption, on freely behaving small animal subjects in large experimental arenas. The EnerCage system has been tested in one-hour in vivo experiment for wireless power and data communication, and the results show the feasibility of this system. The contributions from this research work are summarized as follows: 1. Development of an inductive link model. 2. Development of an accurate PSC models, with parasitic effects for implantable devices. 3. Proposing the design procedure for the inductive link with optimal physical geometry to maximize the PTE. 4. Design of novel antenna and coil geometry for wireless multiband link: power carrier, forward data link, and back telemetry. 5. Development of a model of overlapping PSCs, which can create a homogenous magnetic in a large experimental area for wireless power transmission at a certain coupling distance. 6. Design and optimization for multi-coil link, which can provide optimal load matching for maximum PTE. 7. Design of the wireless power and data communication system for long-term animal experiments, without interruption, on freely behaving small animal subjects in any shape of experimental arenas.Ph.D

Further Study of (Pincer)Iridium-Catalyzed Aromatic C-H Borylation and the Development of New Arylgermanes for Palladium-Catalyzed Cross-Coupling Reactions

Metal-catalyzed cross-coupling reactions of aryl halides or pseudohalides with nucleophiles have been ubiquitous and powerful tools to construct new C–C bonds in synthetic organic chemistry. Among the nucleophiles, arylboronic acids and their esters (arylboronates) are the most popular reagents due to their versatile reactivity and reasonable stability. In 2016, our group reported a highly efficient aromatic C–H borylation catalyzed by (POCOP)Ir complexes. Here we continued the development of the (pincer)Ir-catalyzed system by surveying a series of iridium and rhodium complexes of pincer ligands. We have disclosed that only iridium complexes supported by pincer ligands with a central aryl donor are capable of catalyzing aromatic C–H borylation. The newly tested (PCP)Ir complex has shown improved chemoselectivity (C–H borylation vs. olefin hydroboration, and sp² C–H vs. sp³ C–H borylation) compared to the previously reported (POCOP)Ir complexes. In terms of regioselectivity, C–H borylation of PhF showed certain variations when different precatalysts were examined. On the other hand, C–H borylation of PhCF₃ generally followed the state-of-the-art C–H borylation catalyzed by the iridium complexes supported by neutral bidentate ligands. In addition to arylboron reagents, group 14 main group reagents have also shown their utility in cross-coupling chemistry. Germanium, positioned between silicon and tin on the periodic table, however, receives much less attention. There are only a few examples of cross-coupling reactions using organogermanes as nucleophiles in the existing literature. Here we have developed a robust and efficient ligandless Pd-catalyzed germylation protocol to prepare arylgermanes with tert-butoxy substituents from aryl bromides. The germylation reagent, sodium tri-tert-butoxygermanate, is readily prepared from commercially available GeCl₂·C₄H₈O₂. This highly efficient catalytic system has a wide substrate scope with excellent isolated yields and only produces NaBr as a byproduct. The newly prepared arylgermanes have been studied in the subsequent Pd-catalyzed cross-coupling reaction. We undertook a detailed screening of reaction conditions to identify the optimal condition. Using fluoride as a base is required for successful catalysis and adding water significantly increases the yield of the desired cross-coupling product. The possible roles of fluoride and water have been discussed. The reaction scope and preliminary chemoselective cross-coupling experiments have shown that the newly prepared arylgermanes indeed have useful and unique reactivity compared to the existing reagents

Transimpedance amplifier using negative impedance compensation

A transimpedance amplifier (TIA) with negative impedance compensation comprises a TIA element and a negative impedance compensator connected to the output terminal of the TIA element. The major components of the negative impedance compensator are a negative impedance element formed by a positive feedback circuit, and a compensation circuit for the parasitic capacitance at the output terminal. The negative impedance compensator changes the equivalent impedance of the output terminal from low to high with respect to the ground, and compensates the parasitic capacitance at the output terminal. Thus, an increase of both bandwidth and voltage gain is achieved

Transimpedance amplifier with negative impedance compensation function

This invention relates to an impedance-transfer amplifier with a negative impedance compensation function including elements of single-stage impedance-transfer amplifier and a negative impedance compensator connected to the output end of the amplifier element, which is realized in many ways including a negative resistance element composed of positive and negative circuits and a compensation circuit against the parasitic capacitance effect generated by its output end, and the compensator increases the equivalent earth impedance of the output of the single-stage impedance-transfer amplifier and compensates the parasitic capacitance effect

A 10Gb/s burst-mode/continuous-mode laser driver with current-mode extinction compensation circuit

No description supplie

Application of Nondestructive Testing in Cyclic Fatigue Evaluation of Endodontic Ni-Ti Rotary Instruments

The purpose of this study was to investigate the application of nondestructive testing in cyclic fatigue evaluation of endodontic ProFile( R) nickel-titanium (NiTi) rotary instruments. As-received ProFile(R) instruments were made to rotate freely in sloped metal blocks by a contra- angle handpiece mounted on a testing machine. Rotation was interrupted periodically, and the instrument removed and engaged onto a device to monitor its stiffness by using two strain gauges in four different directions. This monitoring method has the potential to be developed into a convenient, nondestructive turnkey system that allows in situ assessment of the integrity of NiTi instruments in the clinic. Upon fracture, which was indicated by a change in instrument stiffness, the fractured surface would be examined under a scanning electron microscope. Microscopic evaluation indicated a small area of fatigue fracture with a large area of final ductile fracture, whereby the latter was the major cyclic failure mode. Based on the results of this study, we concluded that a potential nondestructive integrity assessment method for NiTi rotary instruments was developed

Multifocal synchronous angiomyolipomas in a kidney and lungs

Angiomyolipoma (AML) is a benign tumor composed of vascular, adipose, and muscle tissues. AML commonly occurs in the kidneys, and is associated with tuberous sclerosis. Different sizes of AML have been reported in the literature. In general, a giant or huge AML usually refers to a tumor size greater than 10 cm in diameter. Several studies have suggested that a giant AML is associated with an increased risk of complications. Herein, we report a case of a giant AML in a 56-year-old patient with abdominal bloating for 6 months. Ultrasound and computed tomography examinations revealed a giant renal AML as well as multiple pulmonary tumors, and thus the patient was scheduled for nephrectomy and pulmonary wedge resection. The resected mass measured 24.6 × 18.4 × 27.3 cm. This report also reviews all previously described cases of large AMLs. Keywords: Angiomyolipoma, Tuberous sclerosis, Nephrectomy, Therapeuti