There is a great interest in low-cost, versatile microfluidic platforms of which the fabrication processes are rapid, straightforward, and translatable to industrial mass productions. In addition, it is beneficial for microfluidic devices to be reconfigurable in the field, so that multiple functions can be realized by a minimum number of devices. Here, we present a versatile acrylic-tape platform which allows highly accessible rapid prototyping of microfluidic devices, as well as device reconfiguration to realize different functions. The clean-room-free fabrication and sealing process only requires a laser cutter, acrylic, and tapes and can be done by an untrained person in the field. We experimentally characterized the relationship between the capillary flow speed and the channel height, the latter of which can be well controlled by the fabrication process. Reconfiguration of microfluidic functions was demonstrated on a single acrylic-tape device, thanks to the reversible sealing enabled by functional tapes. Different pumping mechanisms, including on-chip pumps for better portability and syringe pumps for precise fluid control, have been employed for the demonstration of two-phase flow and droplet generation, respectively. The low-cost and versatile acrylic-tape microfluidic devices are promising tools for applications in a wide range of fields, especially for point-of-care biomedical and clinical applications.

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Tapered optical fibers are versatile tools with a wide spectrum of applications, ranging from sensing to atomic physics. In this work, we developed a highly accessible and controllable fiber tapering system to fabricate tapered optical fibers with a routine optical transmission of 95% and above. With an optimal design, optical transmissions higher than 99% have been experimentally demonstrated. We achieved such results by developing two unique components in a traditional heat-and-pull system: a custom-made miniature heater named as the ceramic housed electric furnace (CHEF) and a real-time, frequency-domain monitoring method. The CHEF enables a well-controlled, uniform, and stable heating zone for an adiabatic tapering process, while the frequency-domain monitoring empowers one to reliably terminate the tapering right after the single-mode trigger. We designed and fabricated the CHEF using low-cost and readily accessible materials and equipment, in order to benefit a broader audience. We carried out a parametric study to systematically characterize the CHEF performance and provided guidelines for the CHEF design, fabrication, and operation. The frequency-domain monitoring method was developed based on our understanding of the dynamic evolution of optical modes in the tapered fiber. Such a method allows real-time visualization of the number of optical models and characterization of the taper adiabaticity during the tapering process, both of which are not available with the commonly used time-domain monitoring. The developed CHEF-based fiber tapering system will meet the urgent need of high-quality tapered optical fibers as well as opening doors to new applications of tapered optical fibers.

Membrane-based acoustic metamaterials have been reported to achieve 100% absorption, the acoustic analogue of photonic black-hole. However, the bandwidth is usually very narrow around some local resonance frequency, which limits its practical use. To address this limitation and achieve a broadband absorption, this paper first establishes a theoretical framework for unit cells of air-backed diaphragms, modeled as an equivalent mass-spring-dashpot system. Based on the impedance match principle, three different approaches are numerically investigated by tuning the cavity length, the static pressure in the cavity, and the effective damping of perforated plates. A prototype with polyimide diaphragm and 3D printed substrate is then fabricated and characterized using an acoustic impedance tube. Preliminary experiments show the feasibility to achieve an absorption bandwidth of ∼200 Hz at center frequency of 1.45 kHz. This work pays the way for developing a sub-wavelength light weight broadband acoustic absorber for a variety of applications in noise control.