# The Design and Investigation of Hybrid a Microfluidic Micromizer
## 1 Introduction
In addition, the passive-type microfluidics micromixer is more reliable and robust because of its simplicity and cost-effectiveness [19]. In a passive mixer, the geometrical characteristics of the microchannel are utilised in many microfluidics systems due to its larger system stability [20]. Moreover, mass transfer is also dominated in the passive microfluidics system by molecular diffusion and convection shortening the diffusion paths [21]. Passive micromixers were used to create nanoparticles in continuous, batch, or semi-batch modes [22]. On the other hand, some disadvantages are also studied due to a lack of precise control; mixing efficiency is also limited in a passive-type micromixer, and there have been some design constraints to obtain higher mixing performance. [PERSON] et al. [23] reported 3D PDMS microfluidics micromixers based on splitting-stretching and then recombined fluid streams in order to enhance diffusion that increases mixing with low Reynolds numbers. [PERSON] et al. [24] examined the impact of microchannel width, applied voltage, and waveform on fluid mixing and flow characteristics numerically and experimentally. They used a passive approach to investigate the mixing performance of a micromixer. [PERSON] et al. [25] explored a novel approach to improve mixing within microfluidic devices for various applications. They also used ridges or slanted walls and varied the various geometrical configurations and patterns to evaluate the mixing performance of the microfluidic device using numerical simulations. [PERSON] et al. [26] developed a Y-shaped turbulent microfluidics micromixer made of PDMS and glass substrate in order to investigate mixing performance using experimental and numerical approaches. [PERSON] et al. [27] used the fractal principle with a multi-objective genetic algorithm and multi-objective optimisation of the cantor fractal baffle microfluidics micromixer to investigate the mixing performance at different Reynolds numbers. [PERSON] et al. studied the optimal design of the passive T-mixer, which involved the prescribed pattern of barriers and furrows with various geometrical configurations using a numerical approach. [PERSON] et al. [28] conducted a topology optimisation in order to enhance the mixing performance for microfluidic micromixers based on the Tesla valve principle. Today, the acoustic wave-based approach has been widely applied in order to facilitate microfluidics due to its flexible control, short mixing distance, and intensive kinetic of biofluids [29]. Acoustic radiation and acoustic streaming are the two main phenomena that are used in microfluidics. The acoustic radiation force refers to the time-averaged force resulting from the time-harmonic nature of acoustic waves. On the other hand, the averaged flow produced by the non-linear interaction of the harmonic acoustic fields is known as acoustic flow [30]. In addition, some microstructures or microbubbles were added to the microchannel to improve acoustic mixing and mixing efficiency [31]. As a result, adaptable acoustic-facilitated micromixers have been used in a variety of domains, including materials synthesis, cell manipulation, and enzyme bioassay [32]. The mixing efficiency is an important parameter for measuring the proper mixing of heterogeneous biofluids and biochemicals [33]. There are several factors such as the total flow rate, the flow rate ratio, and other geometrical features that influence the mixing performance in microfluidics systems, although higher flow rates result in a shorter contact area in the microchannels and shorter mixing times [34]. On the other hand, a lower flow rate ratio might result in thinner layers that are wrapped by the sheath flow in a flow focus area and thus a shorter diffusion in lengths. Moreover, geometrical shapes in microfluidic channels are also influenced by mixing performance [35]. There are two common kinds of mixing geometry in passive microfluidics systems that greatly rely on the laminar diffusion mechanism, consequently limiting their mixing effectiveness.