Increase In Transference Number Research Articles

Dexterous Control of Seven Functional Hand Movements Using Cortically-Controlled Transcutaneous Muscle Stimulation in a Person With Tetraplegia.

Individuals with tetraplegia identify restoration of hand function as a critical, unmet need to regain their independence and improve quality of life. Brain-Computer Interface (BCI)-controlled Functional Electrical Stimulation (FES) technology addresses this need by reconnecting the brain with paralyzed limbs to restore function. In this study, we quantified performance of an intuitive, cortically-controlled, transcutaneous FES system on standardized object manipulation tasks from the Grasp and Release Test (GRT). We found that a tetraplegic individual could use the system to control up to seven functional hand movements, each with >95% individual accuracy. He was able to select one movement from the possible seven movements available to him and use it to appropriately manipulate all GRT objects in real-time using naturalistic grasps. With the use of the system, the participant not only improved his GRT performance over his baseline, demonstrating an increase in number of transfers for all objects except the Block, but also significantly improved transfer times for the heaviest objects (videocassette (VHS), Can). Analysis of underlying motor cortex neural representations associated with the hand grasp states revealed an overlap or non-separability in neural activation patterns for similarly shaped objects that affected BCI-FES performance. These results suggest that motor cortex neural representations for functional grips are likely more related to hand shape and force required to hold objects, rather than to the objects themselves. These results, demonstrating multiple, naturalistic functional hand movements with the BCI-FES, constitute a further step toward translating BCI-FES technologies from research devices to clinical neuroprosthetics.

One-Dimensional Glass Micro-Fillers in Gel Polymer Electrolytes for Li-O2 Battery Applications

Gel polymer electrolytes (GPEs) are composed of liquid electrolytes in polymer matrices and have been widely used in lithium batteries. The incorporation of fillers in electrolytes has been shown to improve Li+ transport properties due to the interaction of filler materials with the polymer, solvent, or salt. In this work, we report on the preparation of composite GPEs (cGPEs) that contain one-dimensional glass micro-fillers of approximately 1micron in diameter and with an aspect ratio exceeding 100. The cGPEs were electrochemically characterized for Li+ transport properties and were shown to have as high as 37% improvement in ionic conductivity and 25% increase in transference number compared to GPEs, using cGPE with 1% micro-fillers. Li-oxygen batteries containing these cGPEs have also demonstrated superior charge/discharge cycling performance with as a high as 86% more cycles of 500 mAh·g−1 for cGPE-1% batteries compared to GPE batteries. Using electrochemical impedance spectroscopy, this improvement was traced to the stabilization of the interfacial resistances in the batteries owing to the improved Li+ transport properties.

Fast Charge/Discharge of Li Metal Batteries Using an Ionic Liquid Electrolyte

Because of their potentially superior safety characteristics, room temperature ionic liquids (RTILs or ILs) have been vigorously researched as a potential replacement for current commercial lithium battery electrolytes, which are based on volatile and flammable organic carbonates. However, relatively poor battery performance, which is a consequence of the higher viscosity and lower conductivity of these materials, has prevented them becoming mainstream electrolytes for commercial lithium batteries. Amongst various RTILs, those containing the bis(fluorosulfonyl)imide (FSI) anion exhibit high conductivities and diffusivities, making them interesting potential electrolytes for lithium metal batteries. Here, we evaluate the electrochemical stability, lithium electrochemistry, and Li+ transference numbers of FSI-based ionic liquid electrolytes intended for use in rechargeable Li metal batteries. We show that ILs containing high concentrations of lithium, up to 3.2 mol.kg−1 in C3mpyr FSI, have excellent rate capability (higher than that of standard battery electrolytes) with both the lithium metal electrode and LiCoO2 cathode, in spite of their significantly higher viscosities and lower conductivities. This unusual behavior is ascribed to the concomitant increase in transference number with increasing Li-salt concentration.