The Experts below are selected from a list of 11526 Experts worldwide ranked by ideXlab platform
Robert J. Wood - One of the best experts on this subject based on the ideXlab platform.
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untethered flight of an insect sized flapping wing microscale aerial vehicle
Nature, 2019Co-Authors: Michael Karpelson, Robert J. Wood, Noah T Jafferis, Farrell E HelblingAbstract:Heavier-than-air flight at any scale is energetically expensive. This is greatly exacerbated at small scales and has so far presented an insurmountable obstacle for untethered flight in insect-sized (mass less than 500 Milligrams and wingspan less than 5 centimetres) robots. These vehicles1-4 thus need to fly tethered to an offboard power supply and signal generator owing to the challenges associated with integrating onboard electronics within a limited payload capacity. Here we address these challenges to demonstrate sustained untethered flight of an insect-sized flapping-wing microscale aerial vehicle. The 90-Milligram vehicle uses four wings driven by two alumina-reinforced piezoelectric actuators to increase aerodynamic efficiency (by up to 29 per cent relative to similar two-wing vehicles5) and achieve a peak lift-to-weight ratio of 4.1 to 1, demonstrating greater thrust per muscle mass than typical biological counterparts6. The integrated system of the vehicle together with the electronics required for untethered flight (a photovoltaic array and a signal generator) weighs 259 Milligrams, with an additional payload capacity allowing for additional onboard devices. Consuming only 110-120 milliwatts of power, the system matches the thrust efficiency of similarly sized insects such as bees7. This insect-scale aerial vehicle is the lightest thus far to achieve sustained untethered flight (as opposed to impulsive jumping8 or liftoff9).
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Milligram scale high voltage power electronics for piezoelectric microrobots
International Conference on Robotics and Automation, 2009Co-Authors: Michael Karpelson, Gu-yeon Wei, Robert J. WoodAbstract:Piezoelectric actuators can achieve high efficiency and power density in very small geometries, which shows promise for microrobotic applications, such as flapping-wing robotic insects. From the perspective of power electronics, such actuators present two challenges: high operating voltages, ranging from tens to thousands of volts, and a low electromechanical coupling factor, which necessitates the recovery of unused electrical energy. This paper explores the power electronics design problem by establishing the drive requirements of piezoelectric actuators, presenting circuit topologies and control methods suitable for driving different types of piezoelectric actuators in microrobotic applications, and demonstrating experimental realizations of sub-100mg power electronics circuits.
Noah T Jafferis - One of the best experts on this subject based on the ideXlab platform.
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untethered flight of an insect sized flapping wing microscale aerial vehicle
Nature, 2019Co-Authors: Michael Karpelson, Robert J. Wood, Noah T Jafferis, Farrell E HelblingAbstract:Heavier-than-air flight at any scale is energetically expensive. This is greatly exacerbated at small scales and has so far presented an insurmountable obstacle for untethered flight in insect-sized (mass less than 500 Milligrams and wingspan less than 5 centimetres) robots. These vehicles1-4 thus need to fly tethered to an offboard power supply and signal generator owing to the challenges associated with integrating onboard electronics within a limited payload capacity. Here we address these challenges to demonstrate sustained untethered flight of an insect-sized flapping-wing microscale aerial vehicle. The 90-Milligram vehicle uses four wings driven by two alumina-reinforced piezoelectric actuators to increase aerodynamic efficiency (by up to 29 per cent relative to similar two-wing vehicles5) and achieve a peak lift-to-weight ratio of 4.1 to 1, demonstrating greater thrust per muscle mass than typical biological counterparts6. The integrated system of the vehicle together with the electronics required for untethered flight (a photovoltaic array and a signal generator) weighs 259 Milligrams, with an additional payload capacity allowing for additional onboard devices. Consuming only 110-120 milliwatts of power, the system matches the thrust efficiency of similarly sized insects such as bees7. This insect-scale aerial vehicle is the lightest thus far to achieve sustained untethered flight (as opposed to impulsive jumping8 or liftoff9).
Michael Karpelson - One of the best experts on this subject based on the ideXlab platform.
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untethered flight of an insect sized flapping wing microscale aerial vehicle
Nature, 2019Co-Authors: Michael Karpelson, Robert J. Wood, Noah T Jafferis, Farrell E HelblingAbstract:Heavier-than-air flight at any scale is energetically expensive. This is greatly exacerbated at small scales and has so far presented an insurmountable obstacle for untethered flight in insect-sized (mass less than 500 Milligrams and wingspan less than 5 centimetres) robots. These vehicles1-4 thus need to fly tethered to an offboard power supply and signal generator owing to the challenges associated with integrating onboard electronics within a limited payload capacity. Here we address these challenges to demonstrate sustained untethered flight of an insect-sized flapping-wing microscale aerial vehicle. The 90-Milligram vehicle uses four wings driven by two alumina-reinforced piezoelectric actuators to increase aerodynamic efficiency (by up to 29 per cent relative to similar two-wing vehicles5) and achieve a peak lift-to-weight ratio of 4.1 to 1, demonstrating greater thrust per muscle mass than typical biological counterparts6. The integrated system of the vehicle together with the electronics required for untethered flight (a photovoltaic array and a signal generator) weighs 259 Milligrams, with an additional payload capacity allowing for additional onboard devices. Consuming only 110-120 milliwatts of power, the system matches the thrust efficiency of similarly sized insects such as bees7. This insect-scale aerial vehicle is the lightest thus far to achieve sustained untethered flight (as opposed to impulsive jumping8 or liftoff9).
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Milligram scale high voltage power electronics for piezoelectric microrobots
International Conference on Robotics and Automation, 2009Co-Authors: Michael Karpelson, Gu-yeon Wei, Robert J. WoodAbstract:Piezoelectric actuators can achieve high efficiency and power density in very small geometries, which shows promise for microrobotic applications, such as flapping-wing robotic insects. From the perspective of power electronics, such actuators present two challenges: high operating voltages, ranging from tens to thousands of volts, and a low electromechanical coupling factor, which necessitates the recovery of unused electrical energy. This paper explores the power electronics design problem by establishing the drive requirements of piezoelectric actuators, presenting circuit topologies and control methods suitable for driving different types of piezoelectric actuators in microrobotic applications, and demonstrating experimental realizations of sub-100mg power electronics circuits.
Louis J Fabri - One of the best experts on this subject based on the ideXlab platform.
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a robust robotic high throughput antibody purification platform
Journal of Chromatography A, 2016Co-Authors: Peter M Schmidt, Michael Abdo, Rebecca E Butcher, Pierre Scotney, Melanie Louise Ramunno, Genevieve Martinroussety, Catherine M Owczarek, Matthew P Hardy, Chaoguang Chen, Louis J FabriAbstract:Abstract Monoclonal antibodies (mAbs) have become the fastest growing segment in the drug market with annual sales of more than 40 billion US$ in 2013. The selection of lead candidate molecules involves the generation of large repertoires of antibodies from which to choose a final therapeutic candidate. Improvements in the ability to rapidly produce and purify many antibodies in sufficient quantities reduces the lead time for selection which ultimately impacts on the speed with which an antibody may transition through the research stage and into product development. Miniaturization and automation of chromatography using micro columns (RoboColumns ® from Atoll GmbH) coupled to an automated liquid handling instrument (ALH; Freedom EVO ® from Tecan) has been a successful approach to establish high throughput process development platforms. Recent advances in transient gene expression (TGE) using the high-titre Expi293F™ system have enabled recombinant mAb titres of greater than 500 mg/L. These relatively high protein titres reduce the volume required to generate several Milligrams of individual antibodies for initial biochemical and biological downstream assays, making TGE in the Expi293F™ system ideally suited to high throughput chromatography on an ALH. The present publication describes a novel platform for purifying Expi293F™-expressed recombinant mAbs directly from cell-free culture supernatant on a Perkin Elmer JANUS-VariSpan ALH equipped with a plate shuttle device. The purification platform allows automated 2-step purification (Protein A—desalting/size exclusion chromatography) of several hundred mAbs per week. The new robotic method can purify mAbs with high recovery (>90%) at sub-Milligram level with yields of up to 2 mg from 4 mL of cell-free culture supernatant.
M P Graziano - One of the best experts on this subject based on the ideXlab platform.
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purification of Milligram quantities of human leptin from recombinant e coli
Hormone and Metabolic Research, 1996Co-Authors: Ahmad Fawzi, Hongtao Zhang, M Van Heek, M P GrazianoAbstract:Leptin, the product of the obese (ob) gene, is a 16 kilodalton protein secreted from adipose tissue. Restoration of leptin to obese ob/ob mice leads to normalization of body weight. The effect of leptin in larger animals has not been explored, in part because of limited supplies of leptin. To date, the potency and yield of recombinant leptin purified from a variety of eukaryotic sources or from E. coli has been highly variable. While purification of leptin from E. coli inclusion bodies has afforded the greatest yield of protein, its potency is at least an order of magnitude lower than that of leptin secreted from E. coli or eukaryotic cells. The mechanistic basis of this difference in potency is not clear at present. The ability to purify significant quantities of highly active leptin will be crucial for the evaluation of leptin structure, as well as its function in additional animal models of obesity. We now report a facile protocol for the preparation of recombinant leptin using an E. coli expression system. 75-85 Milligrams of leptin with a purity of greater than 97 % was prepared from a liter of recombinant E. coil. The procedure can be performed in less than 48 h and requires no chromatography. Intraperitoneal injection of 0.1 mg/kg renatured leptin into ob/ob mice results in a significant reduction in food consumption. The potency of this material is similar to the most potent recombinant leptin described to date. The ability to rapidly prepare large quantities of high specific activity material will hasten the definition of leptin's role in non-rodent models of obesity.
