## 1 Introduction  
Microfluidic technology, also known as Lab-on-a-Chip, is a technology that manipulates tiny fluids on the micrometer scale [1]. It achieves a high level of integration and automation of the experimental process by miniaturizing various functional units of the laboratory [2]. The main advantage of this technology is its ability to significantly reduce the consumption of reagents and samples, lower experimental costs, and improve the accuracy and repeatability of experiments [3]. Therefore, microfluidic technology has been widely used in fields such as biomedicine, chemical analysis, and environmental monitoring. Immunoassay is a method of analyzing specimens using immunological techniques, and is mainly used in clinical testing to detect antibodies or antigenic substances in body fluids through antigen-antibody reactions [4]. The key to this detection method lies in the specific binding of antigens and antibodies. An antigen is a substance that can induce a specific immune response in the body, usually a protein with a molecular weight greater than 5000, while an antibody is an immunoglobulin that can specifically bind to antigens [5]. Performing immunoassay on a microfluidic platform can not only significantly save samples but also increase the speed and sensitivity of detection, which is of great significance for early disease diagnosis and biological research [6]. However, there are some obvious drawbacks to the current microfluidic immunoassay technology [7]. One of the most critical issues is that the detection process is often limited by the slow molecular diffusion process, which makes it difficult for antigens to rapidly reach the functionalized surface coated with antibody probes, thus affecting the efficiency and sensitivity of detection [8]. To overcome this limitation, convective acceleration technology has been introduced into microfluidic systems [9]. In microfluidic systems, electrohydrodynamics (EHDs) is a technology that uses an external electric field to exert electric forces on polarized fluid molecules, thereby generating active motion of the liquid medium and free particles monodispersed within [10]. This non-mechanical fluid driving method is particularly important in the field of microfluidics because it can provide precise fluid control [11]. Electric-field-driven fluid technology, including electro-osmotic and electrothermal flow, is a widely used method in microfluidic scenarios [12; 13; 14]. Electro-osmosis is a fluid motion caused by an electric field, which relies on the electromigration of mobile counterions within a thin electric double layer at a charged solid/electrolyte interface, thus generating a plug-like pump flow profile within a straight microchannel [15; 16; 17]. One of the main drawbacks of electro-osmotic streaming is that it is not effective in fluids with high electrical conductivity, and its driving effect is mainly limited to the vicinity of the fluid-solid interface. As a result, backflow is very likely to occur for a large distance away from charged channel walls [18; 19]. Electrothermal flow, on the other hand, drives fluid motion through the thermal physical effects generated by an external electric field [20]. AC electrothermal flow (ACET) is particularly noteworthy because it originates from the action of the volume expansion force due to the smeared structural polarization of the fluid bulk of thermal-induced inhomogeneous electrical properties, which can effectively penetrate throughout the entire fluid volume, thereby producing uniform and effective electrokinetic flow with negligible backflow. AC electrothermal flow has two main categories: traveling-wave electrothermal flow (TWET) [21; 22; 23; 24] and standing-wave electrothermal flow(SWET) [25; 26; 27; 28]. TWET refers to the AC electric field applied to the electrodes propagating in the form of a traveling wave, thereby generating a continuous pumping flow field along the signal-phase transmission [29].