“Hot flow in the cold

changes shape in a dead world

comes matter to life”

Programmable matter that allows free shape transfiguration and locomotionon command promises ubiquitous access to objects or functions of interest.Current approaches for the autonomous reshaping of solid objects (smartmaterials, soft actuators, modular robotics) are limited in spatial resolution andshape. Solid-liquid phase change pumping as a mechanism for the contactlesstransfiguring and locomotion of solid objects is introduced. Thin objects aredeformed into any intended shape with sub-millimeter resolution and the abilityto freely change their topology is demonstrated, including adding or removingholes, splitting and merging. The unique locomotion of objects throughmillimeter-sized constrictions narrower than their body size is demonstrated,followed by restoring the original shape. This approach opens up avenues fordeveloping autonomous programmable matter with free shape transfiguration.

Stimuli-responsive materials with reversible supramolecular networks controlled by a change in temperature are of interest in medicine, biomedicine and analytical chemistry. For these materials to become more impactful, the development of greener synthetic practices with more sustainable solvents, lower energy consumption and a reduction in metallic catalysts is needed. In this work, we investigate the polymerisation of N-acryloyl glycinamide monomer by single-electron transfer reversible-deactivation radical polymerisation and its effect on the cloud point of the resulting PNAGA polymers. We accomplished 80% conversion within 5 min in water media using a copper wire catalyst. The material exhibited a sharp upper critical solution temperature (UCST) phase transition (10–80% transition within 6 K). These results indicate that UCST-exhibiting PNAGA can be synthesized at ambient temperatures and under non-inert conditions, eliminating the cost- and energy-consuming deoxygenation step. The choice of copper wire as the catalyst allows the possibility of catalyst recycling. Furthermore, we show that the reaction is feasible in a simple vial which would facilitate upscaling.

This paper presents an open source design support tool for a respiratory and cardiac signal acquisition system that utilizes programmable switched-capacitor analog filters in the analog front end. The proposed filter topologies are based on cascaded second-order-section filters and are designed to be programmable in terms of the cut-off frequency via the switching frequency. The design support tool is written in Python and is capable of calculating the capacitance ratios for a given second-order filter topology, generating a parameter file, and performing periodic AC simulations of the designed circuit in SpectreRF. The tool uses a simple estimation algorithm to find the best possible integer fit with an error cost function. Two sets of 6th-order switched-capacitor filter sets are designed using biquadratic sections in 180nm CMOS process. The proposed design methodology offers a better area fraction reduction compared to simple integer ratio designs. Post-layout simulation results demonstrate the effectiveness and efficiency of the proposed design support tool for switched-capacitor analog filters in respiratory and cardiac signal acquisition systems.

In sliding microfluidic platforms (“SlipChip” [1]), two plates with microfluidic wells slide in close contact to perform multiplexed reactions in a single operation. In- plane “sliding-flow” liquid transport, however, limits the potential assay operations to 1) sample compartmentalization/metering, 2) reagent addition, 3) mixing, and 4) aliquoting. Here, we introduce a three-plate sliding microfluidics platform, “Slip-X-Chip”, that additionally includes out-of-plane “cross-flow” liquid transport. Slip-X-Chip allows two additional assay operations: 5) sample concentration and 6) liquid exchange/washing, while retaining the simplicity of operation (one-step operation; no precise pipetting required; no external equipment). These additional assay operations extend the range and complexity of applications enabled by sliding microfluidics. We here demonstrate 1) splitting bead solutions in compartments with different concentrations and 2) compartmentalizing human cells from solution, followed by a viability assay. We foresee that Slip-X-Chip could be further adapted to, e.g., cell counting, cell staining, or ELISA. 

Structures that are periodic on a microscale in three dimensions are abundant in nature, for example, in the cellular arrays that make up living tissue. Such structures can also be engineered, appearing in smart materials(1-4), photonic crystals(5), chemical reactors(6), and medical(7) and biomimetic(8) technologies. Here we report that fluid-fluid interfacial energy drives three-dimensional (3D) structure emergence in a micropillar scaffold. This finding offers a rapid and scalable way of transforming a simple pillar scaffold into an intricate 3D structure that is periodic on a microscale, comprising a solid microscaffold, a dispersed fluid and a continuous fluid. Structures generated with this technique exhibit a set of unique features, including a stationary internal liquid-liquid interface. Using this approach, we create structures with an internal liquid surface in a regime of interest for liquid-liquid catalysis. We also synthesize soft composites in solid, liquid and gas combinations that have previously not been shown, including actuator materials with temperature-tunable microscale pores. We further demonstrate the potential of this method for constructing 3D materials that mimic tissue with an unprecedented level of control, and for microencapsulating human cells at densities that address an unresolved challenge in cell therapy.

We introduce microparticle filters with temperature tuneable size cut-off and surface energy. At room temperature, the filter cut-off is 164 ±23 μm, and the filter is water-absorbing/oil-repelling (hydrophilic). At 50 °C, the filter cut-off is 695±31 μm, and the filter is oil-absorbing/water-repelling (hydrophobic).