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On-line counting of the microparticle/bacteria in the liquid medium has great potential in the food safety and biomedical fields. A new low-cost microfluidic device is proposed for the on-line counting of the microparticles/bacteria in the liquid medium. The gradually contracted microchannel and the viscoelastic fluid are combined to achieve the efficient elastic focusing of the particle/bacteria, which significantly improves the counting accuracy by aligning all particles/bacteria in a single position at the center of the microchannel. A simple light resistance-based counting method is designed and integrated with the microchannel, where the low-cost elements including the laser pointer, convex lens, diaphragm, and photodiode, are used to build the optical path of detection. The influence of the flow rate, the particle size, the property of fluid, and the channel structure on the focusing of the particle/bacteria are investigated by the experiment, and the counting ability of the integrated microfluidic device is validated by using different-sized microparticles and the bifidobacterium. With its simple structure, low cost, easy operation, and high efficiency, this microfluidic device is suitable for the commercial applications, such as the on-line counting of the plastic microparticle in water or the colony-forming units (CFU) of bacteria in food., (© 2024 Wiley‐VCH GmbH.)

This paper presents a multi-axis low-cost soft magnetic tactile sensor with a high force range for force feedback in robotic surgical systems. The proposed sensor is designed to fully decouple the output response for normal, shear and angular forces. The proposed sensor is fabricated using rapid prototyping techniques and utilizes Neodymium magnets embedded in an elastomer over Hall sensors such that their displacement produces a voltage change that can be used to calculate the applied force. The initial spacing between the magnets and the Hall sensors is optimized to achieve a large displacement range using finite element method (FEM) simulations. The experimental characterization of the proposed sensor is performed for applied force in normal, shear and 45° angular direction. The force sensitivity of the proposed sensor in normal, shear and angular directions is 16 mV/N, 30 mV/N and 81 mV/N, respectively, with minimum mechanical crosstalk. The force range for the normal, shear and angular direction is obtained as 0-20 N, 0-3.5 N and 0-1.5 N, respectively. The proposed sensor shows a perfectly linear behavior and a low hysteresis error of 8.3%, making it suitable for tactile sensing and biomedical applications. The effect of the material properties of the elastomer on force ranges and sensitivity values of the proposed sensor is also discussed.