A chemically active filtration membrane with incorporated lanthanum oxide nanoparticles enables the removal of bacteria and phosphate at the same time and thus provides a simple device for preparation of drinking water and subsequent safe storage without using any kind of disinfectants.
The technology of 3D-printing has allowed the production of entirely soft pumps with complex chamber geometries. We used this technique to develop a completely soft pneumatically driven total artificial heart from silicone elastomers and evaluated its performance on a hybrid mock circulation. The goal of this study is to present an innovative concept of a soft total artificial heart (sTAH). Using the form of a human heart, we designed a sTAH, which consists of only two ventricles and produced it using a 3D-printing, lost-wax casting technique. The diastolic properties of the sTAH were defined and the performance of the sTAH was evaluated on a hybrid mock circulation under various physiological conditions. The sTAH achieved a blood flow of 2.2 L/min against a systemic vascular resistance of 1.11 mm Hg s/mL (afterload), when operated at 80 bpm. At the same time, the mean pulmonary venous pressure (preload) was fixed at 10 mm Hg. Furthermore, an aortic pulse pressure of 35 mm Hg was measured, with a mean aortic pressure of 48 mm Hg. The sTAH generated physiologically shaped signals of blood flow and pressures by mimicking the movement of a real heart. The preliminary results of this study show a promising potential of the soft pumps in heart replacements. Further work, focused on increasing blood flow and in turn aortic pressure is required.
Inspired by the natural expansion and contraction mechanism, we present a combustion powered soft silicone monoblock pump lasting for over 10 000 pumping cycles.
Mechanistic and kinetic insights
into the removal of soluble nanoparticles as templates for mesopores
now permit scale-up of mesoporous polymer membranes. Investigations
on the effect of pH and nanoparticle dissolution time showed that
pH levels of 0 or 1 are necessary to enable fast pore template dissolution.
Approximately 5 wt % of the originally applied nanoparticles remained
in the membrane due to complete encapsulation by the polymer matrix
but did not contaminate the permeate during prolonged use. We demonstrated
continuous production of 17 m2 (100 m length) of membrane
using a commercial roll-to-roll coating unit. These membranes were
successfully applied in gravitation driven water filtration. The rates
of rejection of bacteria from heavily contaminated natural pond water
were higher than 99.99%.
Membranes are designed to bridge a precise separation process at the nanoscale with industrial applications running at cubic meters per hour. This review outlines materials applied in membrane production with a particular focus on polymers. Membrane performance and created value are directly linked to controlled pore formation. Their economic relevance has created a number of large companies and associated academic research at top institutions. The authors review, therefore, starts from well-established techniques applied in products and then moves on to evolving concepts from academia. Pore formation through hard templating is a versatile field for separation processes. A more detailed view is given on the two known concepts for nanopore formation, namely colloidal templates and random hard salt templating. A comparison between these two concepts underlines their relevance to combine a process specific separation with large scale manufacturing requirements (i.e., upscale possibility, flexible process control and environmental impact).
We present a design and parameter study on 3D-printed, lost-wax-casted and combustion-powered soft silicone pumps, which are internally cooled by the conveyed liquid. Important factors influencing the pumping performance such as gas mixtures, feed rates, and actuation frequencies were thoroughly studied. Furthermore, we reinforced some of the here presented pumps with aramid fabrics in order to achieve partial blocking of the elastomeric flexibility upon combustion expansion. This design measure dramatically increased the pumping capabilities and allowed continuous conveying of water to 13 m (corresponding to 42 ft) of height. We were able to stably operate these novel pumps for more than 30 000 combustion cycles. Therefore, they represent a further step toward long-term stable soft machines with dense power characteristics.
The construction of machines consisting essentially of soft parts is a nascent and multidisciplinary research field between material science, machine engineering, and robotics. Soft silicones represent a promising class of materials for the creation of a vast multitude of biologically inspired entities. In the present work, a new type of mammalian vein‐inspired soft silicone pump is introduced and characterized, which is fabricated by virtual lost‐wax casting of 3D‐printed injection molds. These pumps can be actuated pneumatically or by internal gas combustion and preserve their functionality even after a freezing/unfreezing cycle. The possibility of using medical examination methods such as ultrasonic imaging to directly access flow information inside soft pumps is shown. Based on soda lime glass microspheres, a method is demonstrated to enhance contrast properties during such color online Doppler imaging for a detailed understanding of the inner fluid‐structure interactions.
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