Microdosing for drug delivery application—A review

There is an increasing amount of research on microfluidic actuators with the aim to improve drug dosing applications. Micropumps are promising as they reduce the size and energy consumption of dosing concepts and enable new therapies. Even though there are evident advantages, there are only few examples of industrial microdosing units and micropump technology has not yet found widespread application. To answer the evoked question of what limits the application of microdosing technology for drug delivery, this work provides a comprehensive insight into the subject of drug dosing. We highlight and analyse specific microfluidic challenges and requirements in medical dosing: safety relevant aspects, such as prevention of freeflow and backflow; dosing-specific requirements, such as dosing precision and stability; and system-specific aspects, such as size, weight, and power restrictions or economic aspects. Based on these requirements, we evaluate the suitability of different mechanical micropumps and actuation mechanisms for drug administration. In addition to research work, we present industrial microdosing systems that are commercially available or close to market release. We then summarize outstanding technical solutions that ensure sufficient fluidic performance, guarantee a safe use, and fulfil the specific requirements of medical microdosing

Volume 2 – Conference: Wednesday, March 9

10. Internationales Fluidtechnisches Kolloquium:Group 1 | 2: Novel System Structures Group 3 | 5: Pumps Group 4: Thermal Behaviour Group 6: Industrial Hydraulic

Volume 3 – Conference

We are pleased to present the conference proceedings for the 12th edition of the International Fluid Power Conference (IFK). The IFK is one of the world’s most significant scientific conferences on fluid power control technology and systems. It offers a common platform for the presentation and discussion of trends and innovations to manufacturers, users and scientists. The Chair of Fluid-Mechatronic Systems at the TU Dresden is organizing and hosting the IFK for the sixth time. Supporting hosts are the Fluid Power Association of the German Engineering Federation (VDMA), Dresdner Verein zur Förderung der Fluidtechnik e. V. (DVF) and GWT-TUD GmbH. The organization and the conference location alternates every two years between the Chair of Fluid-Mechatronic Systems in Dresden and the Institute for Fluid Power Drives and Systems in Aachen. The symposium on the first day is dedicated to presentations focused on methodology and fundamental research. The two following conference days offer a wide variety of application and technology orientated papers about the latest state of the art in fluid power. It is this combination that makes the IFK a unique and excellent forum for the exchange of academic research and industrial application experience. A simultaneously ongoing exhibition offers the possibility to get product information and to have individual talks with manufacturers. The theme of the 12th IFK is “Fluid Power – Future Technology”, covering topics that enable the development of 5G-ready, cost-efficient and demand-driven structures, as well as individual decentralized drives. Another topic is the real-time data exchange that allows the application of numerous predictive maintenance strategies, which will significantly increase the availability of fluid power systems and their elements and ensure their improved lifetime performance. We create an atmosphere for casual exchange by offering a vast frame and cultural program. This includes a get-together, a conference banquet, laboratory festivities and some physical activities such as jogging in Dresden’s old town.:Group 8: Pneumatics Group 9 | 11: Mobile applications Group 10: Special domains Group 12: Novel system architectures Group 13 | 15: Actuators & sensors Group 14: Safety & reliabilit

MULTI‐PHYSICAL MODELLING AND PROTOTYPING OF AN ENERGY HARVESTING SYSTEM INTEGRATED IN A RAILWAY PNEUMATIC SUSPENSION

The aim of this PhD thesis is the investigation of an energy harvesting system to be integrated in a railway pneumatic spring to recovery otherwise wasted energy source from suspension vibration. Exploiting the piezoelectric effect to convert the mechanical energy into an electrical one, the final scope consists on the use of this system to power supply one or more sensors that can give useful information for the monitoring and the diagnostics of vehicle or its subsystems. Starting from the analysis of the energy sources, a multi‐physical approach to the study of an energy harvesting system is proposed to take into account all physics involved in the phenomenon, to make the most of the otherwise wasted energy and to develop a suitable and affordable tool for the design. The project of the energy harvesting device embedded in a railway pneumatic spring has been carried out by means of using a finite element technique and multi‐physics modelling activity. The possibility to combine two energy extraction processes was investigated with the purpose of making the most of the characteristics of the system and maximize the energy recovering. Exploiting commercial piezoelectric transducers, an experimental activity was conducted in two steps. A first mock‐up was built and tested on a shaker to develop the device and to tune the numerical model against experimental evidence. In the second step a fullscale prototype of an air spring for metro application with the EH system was realized. In order to test the full‐scale component, the design of a new test bench was carried out. Finally, the Air spring integrated with the EH device was tested and models validated

Volume 1 – Symposium: Tuesday, March 8

Group A: Digital Hydraulics Group B: Intelligent Control Group C: Valves Group D | G | K: Fundamentals Group E | H | L: Mobile Hydraulics Group F | I: Pumps Group M: Hydraulic Components:Group A: Digital Hydraulics Group B: Intelligent Control Group C: Valves Group D | G | K: Fundamentals Group E | H | L: Mobile Hydraulics Group F | I: Pumps Group M: Hydraulic Component

Development of a prosthetic heart valve with inbuilt sensing technology, to aid in continuous monitoring of function under various stenotic conditions

In spite of technological advances in the design of prosthetic heart valves, they are still often subject to complications after implantation. One of the common complications is valve stenosis, which involves the obstruction of the valve orifice caused by biological processes. The greatest challenge in diagnosing the development of valve failure and complications is related to the fact that the valve is implanted and isolated. To continuously monitor the state of the valve and its performance would be of great benefit but practically can only be achieved by instrumenting the implanted valve. In this thesis, we explore the development of a prosthetic valve with inbuilt sensing technology to aid in continuous monitoring of valve function under various stenotic conditions. 22mm polyurethane valves were designed via dipcoating. A custom made mock circulatory system was designed and hydrodynamic testing of the polyurethane valves under different flow rates were performed with Effective orifice area (EOA) and Transvalvular Pressure Gradient (TVPG) being the parameters of interest. Valves were subjected to varying levels of obstruction to investigate the effect obstruction has on the pressure gradient across the valves. Similar tests were performed on a Carpentier Edwards SAV 2650 model bioprosthetic valve for comparison. Polyurethane valves were then instrumented with strain gauges to measure peak to peak strain difference, in response to varying levels of obstructions. All the polyurethane valves exhibited good hydrodynamic performance with EOA (>1cm2) under baseline physiological conditions. It was also discovered that pressure difference across the valves was directly proportional to the flow rate. The pressure difference also demonstrated a slow increase during the initial stages of simulated stenosis and a sudden increase as the obstruction became severe. This provides further evidence to support the ideal that stenosis is a slow progressive disease which may not present symptoms until severe. The peak to peak strain differences also tend to decrease as the severity of the obstruction was increased. The peak to peak strain difference is indicative of the pressures within the valve (intravalvular pressure). The results suggest that directly monitoring the pressures within the valve could be a useful diagnostic tool for detecting valve stenosis. Future works involves miniaturisation of the sensors and also the incorporation of telemetry into the sensor design.In spite of technological advances in the design of prosthetic heart valves, they are still often subject to complications after implantation. One of the common complications is valve stenosis, which involves the obstruction of the valve orifice caused by biological processes. The greatest challenge in diagnosing the development of valve failure and complications is related to the fact that the valve is implanted and isolated. To continuously monitor the state of the valve and its performance would be of great benefit but practically can only be achieved by instrumenting the implanted valve. In this thesis, we explore the development of a prosthetic valve with inbuilt sensing technology to aid in continuous monitoring of valve function under various stenotic conditions. 22mm polyurethane valves were designed via dipcoating. A custom made mock circulatory system was designed and hydrodynamic testing of the polyurethane valves under different flow rates were performed with Effective orifice area (EOA) and Transvalvular Pressure Gradient (TVPG) being the parameters of interest. Valves were subjected to varying levels of obstruction to investigate the effect obstruction has on the pressure gradient across the valves. Similar tests were performed on a Carpentier Edwards SAV 2650 model bioprosthetic valve for comparison. Polyurethane valves were then instrumented with strain gauges to measure peak to peak strain difference, in response to varying levels of obstructions. All the polyurethane valves exhibited good hydrodynamic performance with EOA (>1cm2) under baseline physiological conditions. It was also discovered that pressure difference across the valves was directly proportional to the flow rate. The pressure difference also demonstrated a slow increase during the initial stages of simulated stenosis and a sudden increase as the obstruction became severe. This provides further evidence to support the ideal that stenosis is a slow progressive disease which may not present symptoms until severe. The peak to peak strain differences also tend to decrease as the severity of the obstruction was increased. The peak to peak strain difference is indicative of the pressures within the valve (intravalvular pressure). The results suggest that directly monitoring the pressures within the valve could be a useful diagnostic tool for detecting valve stenosis. Future works involves miniaturisation of the sensors and also the incorporation of telemetry into the sensor design

ESSE 2017. Proceedings of the International Conference on Environmental Science and Sustainable Energy

Environmental science is an interdisciplinary academic field that integrates physical-, biological-, and information sciences to study and solve environmental problems. ESSE - The International Conference on Environmental Science and Sustainable Energy provides a platform for experts, professionals, and researchers to share updated information and stimulate the communication with each other. In 2017 it was held in Suzhou, China June 23-25, 2017

Improved modelling and driving of hydraulic asymmetric cylinders systems

Asymmetric and symmetric cylinder drives are the major actuators for hydraulic linear motion control applications. The asymmetric type is the most popular one and can be found in various areas, industrial, civil and even aerospace. Its compact design in structure and high power to weight ratio are highlighted, but nonlinear behaviours are found in these applications. An asymmetric cylinder is usually controlled by a symmetric ported control valve, which introduces difficulty in the motion control of the cylinder. To avoid such issue, symmetric cylinder drives are typically chosen for high-performance dynamic response applications. This thesis focusses at improving the modelling and driving of the asymmetric cylinder drive system.The major nonlinearities in asymmetric cylinder systems occur when the control valve crosses its null position, causing pressure jumps, and system parameters switching to new values. In this scenario, the system is usually operating at low speed, in which the friction influence is an important factor. In addition, energy efficiency is always a concern in hydraulic applications, a valve-controlled asymmetric cylinder drive can have better controllability than a pump-controlled system, but its energy efficiency is worse than the latter. The aims of this research are to:•Improve modelling of asymmetric cylinder drive systems.•Improve the driving of asymmetric cylinder systems at low speed and velocity reversal with friction consideration.•Combine the advantages of a valve-controlled and a pump-controlled asymmetric cylinder drive system for energy efficiency purpose.A detailed analysis of a valve-controlled asymmetric cylinder system is carried out, and the nonlinearities behaviours are investigated in structure and theory aspects. The simulation modelling in this thesis reveals the system performances when the control valve travels across its null position, and this process is simulated with a numerical solution. An analytical solution is developed, showing that the new analytical solution runs 200 times faster than the original numerical method in simulation. Friction is inevitable in any device and it plays an important role in hydraulic nonlinearities, especially when the system runs at low speed and velocity reversal. Existing friction models are investigated and reviewed, but limited friction models considered the pressure influence in hydraulics. A new friction model for hydraulic system is developed on current LuGre model. This new friction model includes pressure term, acceleration term and velocity term. The new friction model is validated by experimental results and improvements are demonstrated.Under the consideration of energy efficiency, functionality, cost and feasibilities, a hybrid pump-controlled asymmetric cylinder system that combines the merits of a valve-controlled system and a pump-controlled system is implemented. Its pros and cons are investigated and analysed. Its simulation model is built to aid further analysis of the existing nonlinearities.Comparing the simulation results of the hybrid pump-controlled asymmetric cylinder system with the valve-controlled asymmetric cylinder system, the energy efficiency of the hybrid pump-controlled system is 20% better and can be further optimised. The various experimental results validate the simulation model of the hybrid system. Therefore, the functionality and feasibility of the energy efficient design of the hybrid pump-controlled system are validated.The design circuit of the hybrid pump-controlled asymmetric cylinder system is not fully optimised, and improvements can be achieved in future works including replacing the pilot shifted four-way valve with a solenoid valve, adding accumulators to stabilise the pressure in the service line and adding a controller to optimise the system performance.</div

Laboratory electrical studies on the thermo-chemo-mechanics of faults and fault slip.

In nature, electrical signals have been recorded contemporaneously with volcanic and seismic activity, and have been proposed as precursors to earthquakes and volcanic eruptions. In the hydrocarbon industry, streaming potentials are used to investigate steam fronts, thus aiding enhanced oil recovery. There is therefore considerable current interest in electrical signals emanating from the Earth's crust and the mechanisms which give rise to them. Two of the theories that have been proposed to explain electrical signal generation are: The piezoelectric effect, caused by stress changes on piezoelectric minerals, such as quartz, which is found in many crustal rocks. The electrokinetic phenomenon, produced at a solid-liquid interface, where an electrokinetic current such as the streaming potential can be induced through a pressure, chemical or temperature gradient, resulting in electrical charge transport within the moving fluid. In order to investigate the possible mechanisms responsible for the generation of electrical signals in the Earth's crust, carefully controlled laboratory rock deformation and rock physics experiments have been performed under simulated shallow crustal conditions, where both electrical potential signals and acoustic emissions were measured. The deformation strain rate, confining pressure, pore fluid pressure, pore fluid chemistry and temperature were all varied systematically during conventional triaxial rock deformation tests on a range of rock types. Confining pressures were varied from 20 MPa to 100 MPa, pore fluid pressures from 5 MPa to 40 MPa, strain rates from 1.5 x 10"4 s"1 to 1.5 x 10"7 s"1 and temperatures from room temperature (25 C) up to 125 C. Over thirty five experiments were completed at room temperature on rock samples Clashach, Bentheim and Darley Dale sandstones and Portland limestone. More than ten experiments were done at elevated temperature on both dry and saturated samples of Clashach sandstone using a range of pore fluid chemistries. Significant developments in experimental apparatus were necessary for these latter experiments, including the design and construction of an electrical internal heater for the triaxial deformation cell. I identify that, for the temperature range between 25 and 125 C, that the primary sources of electrical potential signal generation are (i) piezoelectric in dry quartz-rich sandstone and (ii) electrokinetic in saturated samples of both sandstones and limestone. Factors that are found to influence the electrical potential signals during deformation include effective pressure, temperature, strain rate, pore fluid type and fluid flow. As failure is approached, both pre-seismic and co-seismic signals are observed with the magnitude of the signals varying with rock type. These observations can be explained by differences in the rock composition and variation in hydraulic and electrical pathways available for electric current flow during rock deformation. Variation in electrical potential difference can be seen during both the compactive and dilatant stages of deformation. At slower strain rates, local rock variation can be seen through changes in electrical potential signals which appear to be obscured at higher strain rates. The change in electrical and streaming potential signals during deformation reflect both the accumulating and accelerating damage identified by acoustic emission prior to fracture and the localisation of damage at dynamic fracture. After failure the potential decreases to a background value where it remains during constant frictional sliding at essentially constant stress. The presence of a crack or fault was identified to affect the electrical and streaming potential signals depending on their relative position with respect to the fault suggesting that electrical potential could be used as a method for fault location. An increase in temperature was found not to affect the mechanical properties within the range of experimental conditions explored. The effect of increased temperature on the electrical potential signals depends on the conditions applied to the rock such as thermal equilibrium times, deformation and ionic species within the pore fluid. If the rock is allowed to reach thermal equilibrium, the electrokinetic reactions between the solid-liquid interface are increased with an average electrical potential increase of 38 mV per 25 C. However, the new surfaces formed during rapid deformation cannot reach equilibrium, so that temperature has no effect on the electrical potential signals during compaction, dilatancy & failure. With this, the results as a whole suggest that in shallow crustal rocks, the change in electrical potential signal with temperature is below the background electrical noise level