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We introduce and experimentally demonstrate an optofluidics-based refractometer structure arranged in a simple free-space Young interferometer design. Our key idea is based on the use of a very simple microfluidic chip structure that consists of one or two flow channels arranged in parallel. We then pass the optical beam through the flow channels of the microfluidic chip. Behind the flow channels, there are two small apertures where the incident optical beam is automatically divided into two optical beams. These two optical beams are propagating in free space for a desired distance before they interfere with each other at the observation plane. Key features include simplicity in design, ease of implementation, and robustness. In the experimental demonstration, we use a 655-nm wavelength laser diode; the free-space propagation distance is 57.5 cm. The two-channel microfluidic chip has a 900-μm channel spacing, a 100-μm channel width, and a 100-μm channel depth (i.e., d/L = 9). Results indicate a sensitivity of 1.34 × 10-4 RIU in measuring the refractive index of the sucrose solution which clearly agrees with the theoretical analysis. A higher sensitivity of 6.19 × 10-6 RIU is also accomplished when the single-channel microfluidic chip with a measured d/L ratio of 0.52 is combined with an optical mask having a 600- μm channel spacing. [ABSTRACT FROM PUBLISHER]

A recent study conducted in Khon Kaen Province, Thailand, evaluated the effectiveness of a technology-assisted intervention aimed at improving water quality and addressing related health issues in communities around key water bodies. The intervention targeted health concerns associated with water contamination, including chronic kidney diseases, skin conditions, hypertension, and neurological symptoms. The study included water quality assessments and health evaluations of 586 residents and implemented a Learning Innovation Platform (LIP) across 13 communities. Results showed significant improvements in the community, including a decrease in hypertension and skin-related health issues, as well as enhanced community awareness and proficiency in implementing simple water quality assessments and treatment. The study demonstrated the value of a comprehensive, technology-driven community approach, effectively enhancing water quality and health outcomes, and promoting greater community awareness and self-sufficiency in managing environmental health risks.

The rice kernel inside a hull is composed of the embryo and endosperm. The embryo or germ of the rice seed will grow and become the shoot and the root parts of a seedling, while the endosperm is an important nutrient source for the embryo in the early stages. Hence, the health of seedlings depends particularly on the sizes of the embryo and endosperm. In this work, we propose and experimentally demonstrate how the embryo and endosperm areas of brown rice can simply be determined. Our key idea is based on the utilization of a smart mobile device equipped with our specifically designed lens module arranged in a simple cross-polarization imaging configuration for acquiring a rice grain image upon the illumination of a white light source and then spatially analyzing the sizes of embryo and endosperm areas. The prototype shows promising results in identifying the sizes of the embryo and endosperm within 2 s per seed with a measurement error of <9 % compared with the use of off-the-shelf image editing software. In addition, the prototype is in a small package of 20×32.5×6.5 c m 3 with 4 kg weight, thus showing high potential to perform in the real scenario.

As fast human temperature screening is needed in large public areas, this paper proposes a low-cost mobile platform module that combines the advantages of analyzing visible and thermal images. In particular, the key idea relies on face detection in the visible image. Then the coordinates of all faces detected are mapped on to the thermal image to determine their corresponding temperatures. Internal temperature compensation and external reference temperature also are employed to reduce the unwanted temperature fluctuation inside the module and in the surrounding environment. Our mobile platform module, called $\unicode{x00B5} {\rm Therm}$, uses a FLIR ONE camera as our visible and thermal imaging cameras. It can simultaneously determine the temperatures of nine people at a speed of 8 frames/second. A field test operation was performed for four days with 1,170 people, with very promising results of 100% sensitivity, 92.6% specificity, and 92.7% accuracy.

The need of mobile microscope is escalating as well as the demand of high quality optical components in low price. We report here a novel needle moving technique to fabricate milli-size lens together with thermal assist moldless method. Our proposed protocol is able to create a high tensile strength structure of the lens and its base which is beneficial for exploiting in convertinga smart phone to be a digital microscope. We observe that no bubble trapped in a lens when this technique is performed which can overcome a challenge problem found in a typical dropping technique. We demonstrate the symmetry, smoothness and micron-scale resolution of the fabricated structure. This proposed technique is promising to serve as high quality control mass production without any expensive equipment required.

We propose and experimentally demonstrate thin-film filter- (TF) based reconfigurable 1 x 2 fiber-optic add-drop switch (FADS) structures. Our key idea is to locate a movable mirror oriented at a desired angle near the TF to switch the desired wavelength optical beams to the wanted switching ports. Our first moderate-optical-isolation TF-based reconfigurable 1 x 2 FADS is in a transmissive design. Another TF-based reconfigurable 1 x 2 FADS structure is in a retroreflective configuration, and it gives a very low optical-coherent cross talk. Our experimental proof of concept using an off-the-shelf four-cavity TF measured center wavelength at 1,545.749 nm and a 0.8 mm x 0.8 mm x 0.15 mm movable mirror confirms a -19 dB and a much improved <-53 dB optical-coherent cross talk for our transmissive and retroreflective configurations, respectively.

A surface plasmon resonance (SPR)-based optical touch sensor structure is proposed that provides high switch sensitivity and requires a weak activating force. Our proposed SPR-based optical touch sensor is arranged in a compact Kretschmann-Raether configuration in which the prism acting as our sensor head is coated with a metal nanofilm. Our optical-based noise rejection scheme relies on wavelength filtering, spatial filtering, and high reflectivity of the metal nanofilm, whereas our electrical-based noise reduction is obtained by means of an electrical signal filtering process. In our experimental proof of concept, a visible laser diode at a 655 nm centered wavelength and a prism made from BK7 with a 50 nm thick gold layer on the touching surface are used, showing a 7.85 dB optical contrast ratio for the first touch. An estimated weak mechanical force of <0.1 N is also observed that sufficiently activates the desired electrical load. It is tested for 51 operations without sensor malfunction under typical and very high illumination of 342 and 3000 lx, respectively. In this case, a measured average optical contrast of 0.80 dB is obtained with a +/-0.47 dB fluctuation, implying that the refractive index change in a small 3.2% of the overall active area is enough for our SPR-based optical touch sensor to function properly. Increasing optical contrast in our SPR-based optical touch sensor can be accomplished by using a higher polarization-extinction ratio and a narrower-bandwidth optical beam. A controlled environment and gold-coated surface using the thin-film sputtering technique can help improve the reliability and the durability of our SPR-based optical touch sensor. Other key features include ease of implementation, prevention of a light beam becoming incident on the user, and the ability to accept both strong and weak activating forces.