Micromachines

The ability to precisely prepare microfluids with targeted concentrations is critical for numerous applications, including protein crystallization and drug efficacy evaluation. This study presents an efficient microfluidic method for the continuous preparation of fluids at desired concentrations utilizing AC electroosmosis (ACEO). Two miscible fluids of different initial concentrations are introduced through separate inlets. Target concentrations are achieved through ACEO-driven mixing, where fluid manipulation via electric signal and flow velocity control enables precise concentration adjustment at the outlet. To elucidate the concentration control mechanism via ACEO, we develop a three-dimensional numerical model coupling electric, flow, and concentration fields. Our results demonstrate that concentration modulation is significantly influenced by intrinsic fluid properties and external control parameters, including fluid viscosity, conductivity, axial fluid velocity, driving voltage, and signal frequency. Specifically, higher fluid viscosity and conductivity dampen electroosmotic flow, necessitating increased voltage to achieve target concentration. Axial fluid velocity determines the residence time in the mixing zone, directly affecting mixing efficiency and concentration control effect. The intensity of ACEO flow increases with applied voltage, enabling tunable mixing performance and outlet concentration. Overall, the simplicity of device design combined with precise concentration manipulation makes this method particularly attractive for applications requiring accurate fluid preparation.

Inflammatory cytokines and proteins are essential indicators of immune status and disease progression; however, conventional assays rely on invasive sampling and complex processing, restricting their use in real-time monitoring. Here, we present a 3D-printed poly(methyl methacrylate) (PMMA) microneedle-based biosensing platform integrated with a tyramide signal amplification–enhanced enzyme-linked immunosorbent assay (TSA–ELISA) for noninvasive and highly sensitive detection of inflammatory biomarkers in interstitial fluid. The microneedles exhibit precise geometry, adequate mechanical strength, and excellent biocompatibility, facilitating efficient skin penetration and biomarker capture. Stepwise chemical functionalization ensured stable antibody immobilization, while TSA significantly amplified detection signals. The platform achieved reliable, reproducible, and multiplex detection of cytokines and albumin in both healthy individuals and patients with inflammatory skin conditions. Notably, the measured cytokine level in lesional skin of eczema patients was 97.7 pg/mL, showing a significant difference from the 62.8 pg/mL observed in healthy subjects. This MN-based TSA–ELISA system offers a robust and minimally invasive strategy for monitoring inflammation-related biomarkers, holding great potential for clinical diagnostics and personalized healthcare applications.

Electrostatic technology has emerged as a crucial tool for sustainable agricultural development due to its multifunctional characteristics. However, systematic and specialized investigations into its mechanism of action and application principles across diverse agricultural scenarios remain insufficient. Here, this review innovatively constructs a spatial scale classification framework and categorizes it into macroscale spray engineering and microscale plant biostimulation. At the macroscale, electrostatic spraying leverages charged droplets’ properties (high surface charge density, strong electrostatic interaction, enhanced adsorption) to improve canopy deposition efficiency and reduce agrochemical drift losses. At the microscale, electrostatic fields induce electron/ion directional movement, providing non-contact stimulation to regulate plant physiological processes such as seed germination and nutrient uptake. We systematically summarize the latest research progress in electrostatic spraying and electrostatic biostimulation, and further compare them in terms of their fundamental mechanisms, targets, and stages of technological development. Finally, the current limitations and challenges for each technology are overviewed and the forward perspective for the efficient application of electrostatics in agriculture are outlined. This review provides theoretical references and technical guidelines for the application research of electrostatic spraying and electrostatic biostimulation, holding significant importance for promoting the standardized development of electrostatic technology in sustainable and precision agriculture.