Stretchable printed circuit boards (S-PCBs) offer unique advantages over rigid PCBs such as enabling conformability to changing environments and ergonomic designs with increased lifetime under dynamic loads. This study introduces an innovative fabrication method and a cost-effective solution for rapid prototyping S-PCBs using commercially available materials. By utilizing silicone substrates with different levels of stiffness and structured copper sheets for electrical connections, the S-PCBs feature ‘stiff islands’ embedded in a flexible base material. This fabrication method helps alleviate mechanical strain on strain-sensitive components while allowing local deformation of the S-PCB. The proposed fabrication method does therefore enable to integrate surface mount device components into S-PCBs and facilitates complex circuit designs while maintaining stretchability and fatigue resistance. Through material characterization, video strain analysis, as well as quasi-static and cyclic loading tests, this article demonstrates the efficacy of our approach. Based on the experimental results, we provide insights into failure modes and suggest design principles to further enhance the durability of S-PCBs fabricated with our method. We then conclude by presenting a soft wearable S-PCB demonstrator. The S-PCBs fabricated with this method withstood mechanical strains up to 100% and cyclic loads with 30% strain up to 625 cycles. The results are very promising for applications in soft robotics, wearable devices, and soft sensors and actuators. Overall, our study offers a comprehensive toolkit for fast S-PCB prototyping, paving the way for advancements in stretchable electronics with a high degree of complexity and stretchability.

Microfluidic devices, especially those utilizing polydimethylsiloxane (PDMS) structures, require reliable bonding methods to achieve durable, leak-proof seals. Current bonding techniques, including O₂ plasma treatment, suffer from limitations related to material compatibility and surface roughness sensitivity, which compromise device stability and scalability in complex designs. In this study, we investigate the impact of surface roughness, wax contamination, and the presence of conductive materials on bonding strength in PDMS-based microfluidics. Additionally, we propose a novel bonding method using a flowable, one-component silicone rubber that forms robust seals without plasma treatment or silanization, effectively overcoming the challenges posed by increased surface roughness and material heterogeneity. The bonding method demonstrated significantly enhanced bond strengths across various substrate combinations (PDMS, copper, and FR4), with notable resilience under high pressure. This approach advances microfluidic fabrication by offering a scalable, versatile solution for multi-material bonding applicable in digital microfluidics and beyond.

The dynamics of a thin low-density polyethylene sheet subject to periodic forcing due to Bénard-Kàrmàn vortices in a long narrow water channel is investigated here. In particular, the time-averaged sheet deflection and its oscillation amplitude are considered. The former is first illustrated to be well-approximated by the static equilibrium between the buoyancy force, the elastic restoring force, and the profile drag based on the depth-averaged water speed. Our observations also indicate that the presence of upstream vortices hinder the overall reconfiguration effect, well-known in an otherwise steady flow. For the sheet-tip oscillations, a simple model based on a torsional-spring-mounted flat plate correctly captures the measured tip amplitude ${\delta }_b$ over a wide range of sheet physical properties and flow conditions. Furthermore, a rich phenomenology of structural dynamics including vortex-forced-vibration, lock-in with the sheet natural frequency, and flow-induced vibration due to the sheet wake, multiple-frequency, and modal response is reported.

This paper presents an open-source miniaturised readout device designed for the wireless interrogation of passive LC sensors and wireless power transmission. The system is based on a Sparkfun RedBoard Artemis microcontroller with a custom-printed circuit board as an extension, providing a compact, low-cost alternative to expensive laboratory-grade equipment. The reader coil is excited by a signal that can be tuned digitally in both frequency and amplitude. The resonance frequency of a wirelessly coupled LC tank is detected by monitoring the voltage minimum of a rectified signal envelope, which corresponds to the impedance change of the reader inductance at resonance. Experimental validation demonstrates that the device accurately tracks resonance frequency shifts resulting from variations of the LC tank’s capacitance, performing comparably to laboratory-grade impedance analysers. Testing the influence of axial separation between the two coils up to 25 $\mathrm{m}$$\mathrm{m}$ showed stable and identifiable voltage dips. The programmable excitation signal peak-to-peak voltage ranges from $0.81$ V to $5.35$ V. The device enables fully stand-alone operation with a display and navigation switch, making it suitable for untethered LC wireless sensing and actuation applications.

Rigid semiconductor‐based controllers constrain the compliance and environmental resilience of soft machines. While fluidic and pneumatic control architectures have provided softer alternatives to conventional electronics, they often lack the compactness, scalability, and integration capacity of digital systems. Here, we introduce a class of 3D‐printed soft mechanical‐electrical logic elements that integrate digital state change directly into the material architecture. The structures are fabricated from thermoplastic polyurethane/polylactic acid (TPU/PLA) parts incorporating liquid metal (LM)‐filled silicone tubes, actuated through a beam‐tooth mechanism. Depending on the configuration, the unit cells exhibit normally open (NO) or normally closed (NC) states, translating mechanical deformation into distinct electrical states. Mechanical and electromechanical characterization revealed reproducible state changes with sharp transitions. The structures’ performance under dynamic loading was tested for 100 cycles. By combining unit cells in series and parallel, we demonstrate Boolean logic primitives (AND, OR, NAND, NOR), each reproducing its truth table. The results provide a foundation for deformation‐triggered electromechanical logic in 3D‐printed soft machines, where local mechanical inputs can be converted into binary electrical states within the material architecture.