## 4 Conclusions  
Our study demonstrates the remarkable precision of stereolithography (SLA) technology coupled with effective post-processing cleaning, allowing for the fabrication of microchannels as small as 200 \(\upmu\)m in width and height. This breakthrough offers the exciting possibility for the creation of intricate microfluidic structures essential for capillary-driven devices. The device has a smaller channel of 502.74 \(\upmu\)m with a standard deviation of 3.235 \(\upmu\)m (designed as 500 \(\upmu\)m). The mix tank has a width of 862.91 \(\upmu\)m with a standard deviation of 12.82 \(\upmu\)m (designed as 850 \(\upmu\)m). The height of the printed channel has a less than 1% error according to the experimental measurements.  
The utilization of capillary-driven systems proved highly effective in achieving the desired mixing quality. Notably, the integration of computational simulations played a pivotal role in predicting the future behavior and optimizing the design of the capillary device, ensuring efficient mixing performance. The experimental findings reveal an average velocity of 13.45 mm/s in channels with dimensions of 500 \(\upmu\)m width \(\times\) 400 \(\upmu\)m height, while a reduced speed of 3.033 mm/s is observed in the mix tank featuring channels with dimensions of 850 \(\upmu\)m width \(\times\) 800 \(\upmu\)m height. During the mixing process, there is a  
Figure 15: Comparative graph of ANSYS simulation and photo of the mixing process.  
notable increase in velocity, reaching an average of 15.09 mm/s within the mix tank. This enhancement in velocity signifies improved efficiency in the mixing process.  
The successful mixing results obtained in this study have broad applications across diverse industries, including biomedicine, food processing, and more. These findings highlight the feasibility of manufacturing efficient mixing systems through SLA additive manufacturing, offering potential solutions to address specific industry challenges and demands. The manufacturing time for the device averages 90 min, with a maximum error of 2.6 % observed in the width of the channel-designed device and less than 1% in its height.  
A noteworthy achievement of this research is the rapidity of fluid mixing within a relatively short microchannel length of 6 mm, with a duration ranging between 3 and 8 s. This efficiency is particularly notable when compared to the existing literature, underlining the effectiveness of our capillary-driven approach in achieving swift and effective mixing. The mixing index obtained through both the simulation and experiments was 0.55, referring to the fluid within the main channel.  
[PERSON] executed the conceptualization, investigation, data analysis, manuscript preparation and wrote the original draft; [PERSON] supervised, reviewed and edited the manuscript. All authors have read and agreed to the published version of the manuscript.  
Not applicable.  
All data generated or analyzed during this study are included in this published article or available from the corresponding author upon reasonable request.  
We gratefully acknowledge ESPE (Universidad de las Fuerzas Armadas) for providing the facilities and resources for the Scanning Electron Microscopy (SEM) microscopy, particularly the Nanomaterials Characterization Laboratory Center of Nanoscience and Nanotechnology (CENCINAT). Special thanks to [PERSON]. We also appreciate the technical assistance Ing. [PERSON] for their guidance and support during the process.  
The authors declare no conflicts of interest.  
The following abbreviations are used in this manuscript:  
\begin{tabular}{l l} SLA & Stereolithography \\ FDM & Fused Deposition Modeling \\ UV & Ultraviolet \\ PP & Polyppropylene \\ IGES & Initial Graphics Exchange Specification \\ SEM & Scanning Electron Microscopy \\ \end{tabular}