Piezoelectric titanium based microfluidic pump and valves for implantable medical applications

Abstract

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.