Michael Loepfe

Combining Phosphate and Bacteria Removal on Chemically Active Filter Membranes Allows Prolonged Storage of Drinking Water

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.

3D printed lost-wax casted soft silicone monoblocks enable heart-inspired pumping by internal combustion

We present a gas combustion powered soft pump made from highly durable and flexible polydimethylsiloxane (soft silicone). Our soft pump was able to run for 10 000 combustion cycles at a constant combustion power rating of 500 watts and thus discloses novel prospects for long-lasting soft-machines at high specific energy-densities.

A Soft Total Artificial Heart—First Concept Evaluation on a Hybrid Mock Circulation

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.

Internal polymer pore functionalization through coated particle templating affords fluorine-free green functional textiles

Outdoor clothing traditionally contains large numbers of fluorinated organic compounds to provide water vapour permeability (breathability) and protection against rain water. Persistence and bioaccumulation of such chemicals, however, have resulted in their partial ban (Stockholm protocol by the United Nations, 2009). In this study, we show how a simple pore inside coating provides polymer membranes from stearic acid, limestone and elastomers. The selective coating of a pores inside is based on first providing a core/shell limestone particle, its incorporation into the elastomer, and subsequent dissolution of the limestone core through dilute acid, leaving the former shell within the polymer pore. The process is transferred to a continuous roll-to-roll coating pilot machine, manufacturing at the m2 scale. The produced membrane is laminated to a textile, and finally tailored into a functional outdoor jacket. The process demonstrated here to selectively alter pore surfaces serves as a platform membrane technology that is broadly applicable to other polymers and provides a new way to membrane manufacturing.