Piezoelectric titanium based microfluidic pump and valves for implantable medical applications

Medical devices often require precise movement of fluids. Automated implants with no need for manual handling improve patient care significantly. However, existing microfluidic devices do not fulfil the necessary specifications of size, safety, hermetic sealing, and artefact free medical imaging, as well as energy efficiency combined with adapted fluidic properties. In this work we designed, manufactured, and experimentally evaluated three piezoelectric microfluidic devices for implant automation: a diaphragm pump, a normally closed valve, and a normally open valve. All devices are made of titanium, minimizing the risk of artefacts in medical imaging. They have similar form factors and use the same actuation method. For the later, a specific mounting process of the piezo actuator enables outstanding fluidic performance during experimental evaluations. The titanium micropumps show a maximal flow of (14 ± 2.2) ml/min and pressure build-up of 75 kPa. The normally closed valve’s leakage rates are extremely low with less than 1 μL/min. Detailed investigations further include the actuator stroke, a lifetime study for normally open valves, and a numerical and experimental evaluation of the normally closed valve’s spring foil. The introduced titanium technology platform is ideally suited for system integration accounted for by the use of the same actuation principle and the similar form factor and a simple design. The development of small, smart, and energy efficient implants for improved treatment is possible based on the introduced platform

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

Piezoelectric Normally Open Microvalve with Multiple Valve Seat Trenches for Medical Applications

Microfluidic systems for medical applications necessitate reliable, wide flow range, and low leakage microvalves for flow path control. High design complexity of microvalves increases the risk of possible malfunction. We present a normally open microvalve based on energy-efficient piezoelectric actuation for high closing forces and micromachined valve seat trenches for reliable valve operation. A comprehensive investigation of influencing parameters is performed by extensive fluidic 3D finite element simulation, derivation of an analytical closed state leakage rate model, as well as fabrication and test of the microvalve. Additional valve seat coating and a high force actuator are introduced for further leakage reduction. The microvalve has a wide-open flow range as well as good sealing abilities in closed state. Extensive fatigue tests of 1 × 106 actuation cycles show that additional coating of the valve seat or increased actuator strength promote sealing performance stability. Analytical calculations of leakage are suitable to estimate experimentally obtained leakage rates and, along with computational fluidic dynamic (CFD) simulations, enable future microvalve design optimization. In conclusion, we demonstrate that the presented normally open microvalve is suitable for the design of safe and reliable microfluidic devices for medical applications

Post-stall flow control using nanosecond pulse driven dielectric barrier discharge plasma actuators

The efficacy of thermal perturbations generated by nanosecond pulse driven dielectric barrier discharge (ns-DBD) plasma actuators for post-stall flow control is explored on a NACA 0012 airfoil. Baseline and controlled flow fields are studied using static pressure measurements, particle image velocimetry and constant temperature anemometry. Experiments are primarily performed at Re = 0.74 × 106 (U ∞ = 40 m s−1) and α = 18°. Three regimes of forcing are identified corresponding to separation control (0.92 \u3c F + \u3c 1.52), bluff body shedding (0.23 \u3c F + \u3c 0.92) and an impulse-like response (F + \u3c 0.23). The response of the flow to a single high voltage pulse is also examined and compared to other studies of transient separation control. Results show that the global structure of the controlled flow is not specific to ns-DBD plasma actuator forcing. Rather, it is the local behavior of the ns-DBD that results in control authority at conditions that are challenging for the majority of active flow control actuators that rely on zero net mass flux momentum addition. The implications of these findings as well as open questions and suggestions for future work are discussed

Experimentelle Charakterisierung, FEM Simulation und analytische Modellierung einer piezoelektrischen Mikroventils mit mehreren Ventilsitzgräben

This dataset contains experimental data as a characterisation of piezoelectric microvalves. Measurement data includes the actuator stroke measured using white light profilometry, as well as fluidic measurements of generated flow, passive flow, and leakage measured using coriflow flowmeters. Experimental data before and after 10^6 actuation cycles fatigue test is supplied. An COMSOL Multiphysics project file is given as part of an evaluation of a design parameter study as well as simulation results in form of csv data. Analytical modelling of leakage rates is implemented in python scripts and associated text files contain calculation results.This research was funded by the Bavarian Ministry of Economic Affairs, Regional Development and Energy, within the Bavarian funding program for research and development “Electronic Systems” under the grant number ESB071/002.The dataset contains .dat files for fluidic measurements; .txt files for stroke measurements; a .mph COMSOL Multiphysics project file with associated .csv result files, and .py Python scripts for analytical modelling. Experimental data, simulation files, and modelling files are collected in separate zip folders, respectively

Experimentelle Charakterisierung und Simulation von piezoelektrischen Mikropumpen und Mikroventilen aus Titan

This dataset contains experimental data as a characterisation of piezoelectric micropumps and microvalves. Measurement data includes the actuator stroke measured using white light profilometry, as well as fluidic measurements of generated flow, passive flow, and leakage measured using coriflow flowmeters. Flow measurement data of normally open valves before and after 10^6 actuation cycles is supplied. An ANSYS 2019 R1 project file is given as part of an evaluation of a normally closed valve's spring foil. Associated with the simulation is experimental data of the pressure-dependant stroke of the normally closed valve's spring foil.The dataset contains .dat files for fluidic measurements; .txt files for stroke measurements; and an ANSYS 2019 R1 project file. Data of micropumps, NO microvalves, NC microvalves, and simulation files are collected in separate zip folders, respectively. The tabular data can be evaluated using EXCEL or Python. Simulation data can be used with ANSYS Version 2019 R1 or higher