Reference electrodes must maintain a well-defined potential for long periods of time to be useful. The silver/silver chloride (Ag/AgCl) reference electrode is arguably the most widely used reference electrode, but it leaks silver and chloride ions into the sample solution through the porous frit over time. Further, the porous frit makes miniaturization to the micro-and nanoscale challenging. Here, we present an alternative, where the traditional Ag/AgCl reference electrode porous frit is replaced by a conductive wire, preventing ion leakage and allowing miniaturization to the microscale. Charge balance is maintained through a closed bipolar electrochemical mechanism, where faradaic processes occur on each end of the sealed wire. Using the above design, we demonstrate the efficacy of the leakless, bipolar reference electrode (BPRE) and miniaturize it to the microscale (μ-leakless BPRE). Importantly, we demonstrate that leakless and μ-leakless BPREs behave the same as commercial reference electrodes during potentiometric measurements and leakless BPREs perform similarly during voltammetric measurements on ultramicroelectrodes. We demonstrate that the drift during voltammetry using a leakless BPRE on a macroelectrode is slightly more appreciable compared to the drift seen with a commercial reference electrode. We detail design principles for the use of leakless BPREs in nonaqueous solvents and in sealing other conductive materials (e.g., gold and carbon). Using mass spectrometry, we show that the maximum leakage of methylene blue is 0.36 fmol/s, at least 2 orders of magnitude smaller than that of commercial reference electrodes. Finally, we demonstrate the efficacy of using leakless BPREs in potentiometric glucose sensing.

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Monodisperse spherical and non-spherical particles as well as their suspensions have diverse applications in optoelectronics, photonics, abrasives, catalysis, drug delivery, and field responsive rheological fluids. The synthesis of highly monodisperse particles with tunable functionalities has been a great challenge. Microfluidics technology, however, presents an attractive approach to synthesizing monodisperse non-spherical particles with tunable functionalities for application breakthroughs. The microfluidics method, described in a previous study, uses a UV-curable prepolymer with an appropriate photoinitiator. The prepolymer solution passes through a microfluidic channel positioned on a microscope stage, and a microscope objective focuses UV light that is launched into the microfluidic channel. A photo mask patterned with transparent geometric features that define the shape of the particles masks the UV light to synthesize micron sized organic particles. Typically, particles synthesized using this method remain suspended. However, this study describes post-processing methods that allow the recovery of high fidelity, solvent-free particles. Particles in cubic, tetragonal and cylindrical shapes as well as those in pentagonal, hexagonal and triangular cross sections with a size range of *40-130 lm were synthesized and collected. Then, they were characterized using electron microscopy and image processing to demonstrate the efficacy of the post processing techniques described.