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With the rapid advancement of microfluidic technology, the precise measurement of microflows is critical in biomedical engineering, chemical analysis, and environmental monitoring. Current measurement methods often suffer from limited scalability and potential interference with fluid dynamics. This study introduces a low detection limit (DL) flow measurement method that uses single-fiber optical tweezers to capture individual silica microspheres outside a microcapillary as flow indicators. Under fluid flow, the microspheres exhibit microscale positional shifts within the optical trap. By analyzing these signal changes in real time, accurate flow measurements are achieved. Our experimental results demonstrate significant advantages in detecting low flow rates using this method. For sample solutions with a concentration of 0.05 wt.%, the method achieves a minimum flow DL of 6 nL/min, a linearity of 0.993, a sensitivity of $- 14.36 \; \mu $ s/(nL/min), and a maximum standard deviation of approximately 0.092%. The piconewton-level optical force allows this sensor structure to detect extremely low flow rates. Additionally, the microcapillary provides a controlled and stable microflow environment, ensuring that the measurement process does not interfere with fluid flow, thereby reducing deviations.

Bone-related diseases like osteoarthritis and osteoporosis impact millions globally, affecting quality of life. Osteoporosis considerably enhances the probability of bone fractures of the wrist, hip, and spine. Enhancement and acceleration of functional bone development can be achieved through the sustained delivery of growth factors (GFs) and cells in biomaterial carriers. The delivery of bioactive compounds in a targeted, spatiotemporal way that most closely resembles the natural defect repair process can be achieved by designing the carrier system with established release kinetics. Furthermore, the carrier can serve as a substrate that mimics the extracellular matrix, facilitating osteoprogenitor cell infiltration and growth for integrative tissue healing. In this report, we explore the significance of GFs within the realm of bone and cartilage tissue engineering, encompassing their encapsulation and delivery methodologies, the kinetics of release, and their amalgamation with biomaterials and stem cells (SCs) to facilitate the mending of bone fractures. Moreover, the significance of GFs in evaluating the microenvironment of bone tissue through reciprocal signaling with cells and biomaterial scaffolds is emphasized which will serve as the foundation for prospective advances in bone and cartilage tissue engineering as well as therapeutic equipment. Nanoparticles are being used in regenerative medicine to promote bone regeneration and repair by delivering osteoinductive growth factors like BMP-2, VEGF, TGF-β. These nanocarriers allow controlled release, minimizing adverse effects and ensuring growth factors are concentrated at the injury site. They are also mixed with mesenchymal stem cells (MSCs) to improve their engraftment, differentiation, and survival. This approach is a key step in developing multi-model systems that more efficiently facilitate bone regeneration. Researchers are exploring smart nanoparticles with immunomodulatory qualities to improve bonre regeneration and reduce inflammation in injury site . Despite promising preclinical results, challenges include cost management, regulatory approval, and long term safety. However, incorporating stem cell transport and growth factors in nanoparticles could revolutionize bone regeneration and offer more personalized therapies for complex bone disorders and accidents.

The majority of edge-bottom water fault-block reservoirs in China have the problem of a low recovery factor during water flooding. Most of them suffer from serious water channeling, a rapid increase in water cut, and low sweeping efficiency. Measures need to be taken to further increase the recovery factor, among which nitrogen foam flooding and viscosity reducer flooding technologies are highly anticipated for this purpose. To fill this gap, this work targets reservoirs with edge-bottom water and fault blocks. First, on the basis of evaluating the effects of foaming agent and viscosity reducer, a 2D visual large flat physical model is designed to simulate the fault-block reservoirs with edge and bottom water. Then, after comparing the oil displacement effects of nitrogen foam and viscosity reducer systems using different injection methods, the flow characteristics and action patterns of foam and viscosity reducer are studied. The recovery factor of the hybrid injection scheme increased by 18.3% compared to the water flooding and was 4.2% higher than the slug injection. The water cutoff of the hybrid injection showed a linear decrease. Finally, the experiment clarifies the impact of injection rounds on nitrogen foam with viscosity reducer flooding and summarizes the mechanism of it through the changes in the oil saturation. The viscosity reducer significantly reduces the viscosity of crude oil and assists in foam plugging. Additionally, as the injection rounds increase, the effectiveness of profile control and water plugging decreases. In addition, most methods of profile control and water plugging are one-time injection; the experiment changes it to multiple rounds and introduces a conversion method of resistivity and oil saturation innovatively. The physical displacement experiment of big-scale size two-dimensional visualization model is carried out under simulated reservoir conditions, the influence of injection methods on recovery factor is studied, and the mechanism of enhancing oil recovery is clarified. Also, it is expected to address issues in edge-bottom water reservoirs with fault blocks, such as severe water channeling and limited displacement range.