# 3D Printed Microfluid Separators for Solid/Liquid Suspensions
## 3 Results and Discussion  
### Characterization of Powders before the Separation  
Figure 3 presents the particle size distribution of baby powder particles, as determined by the sieving method, and introduced as the differential distribution function \(\text{dQ}_{3}(d)\). The results indicate a predominant particle size range of 0-63 um, which accounts for the majority of the powder's composition. This narrow size range suggests a high degree of uniformity. Additionally, the presence of particles in the 180-355 um range signifies the occurrence of agglomerates. Agglomeration is a common phenomenon in powders where individual particles tend to aggregate together, forming larger agglomerates due to van der Waals forces, electrostatic attraction, or moisture content. These agglomerates are often resistant to breakdown during the sieving process, leading to an apparent increase in the measured particle size. Figure 3 reflects the volume particle size distribution of baby powder particles, as determined by the laser diffraction method, and introduced as the differential distribution function \(\text{dQ}_{3}(d)\). The laser diffraction analysis reveals that the majority of the particles are of the sub-100 um sizes, consistent with the intended fine particle size for baby powder. The significant drop in volume percentage beyond this size range indicates an absence of substantially larger particles, highlighting a very fine and consistent particle size distribution. The SEM micrographs of the baby powder sample, depicted in Figure 4, provide a detailed view of the powder's morphology at two different magnifications: 200\(\times\) and 2000\(\times\)  
Figure 3: PSD of pre-separated baby powder; sieve analysis (**left**) and laser diffraction analysis (**right**). These images offer critical insights into the structural characteristics and morphology of the baby powder. At 200\(\times\) magnification, the micrograph shows a heterogeneous mixture of particles with varying sizes and rough surfaces. Larger particles are prominent, indicating a broad range of particle sizes that can affect the powder's flowability and packing density. This irregular morphology is typical for talc-based baby powders and impacts their distribution and application properties. At 2000\(\times\) magnification, the SEM micrograph highlights the plate-like morphology characteristic of talc, with well-defined edges. Finer particles are more evident at higher magnification. The CaCO\({}_{3}\) particles exhibit a broad size distribution (Figure 5) using sieving analysis. The most significant fractions of particles are found in the 180-355 \(\upmu\)m, 355-710 \(\upmu\)m and \(>\)850 \(\upmu\)m intervals, each constituting a substantial proportion of the overall particle volume. Specifically, the 355-710 \(\upmu\)m size range shows the highest peak, indicating a 34.8 volume percentage of particles within this interval. Smaller particle size intervals, such as 0-63 \(\upmu\)m, 63-90 \(\upmu\)m, and 90-125 \(\upmu\)m, display relatively minimal volume percentages, suggesting a lesser presence of fine particles within the CaCO\({}_{3}\) sample. The presence of larger particles can be attributed to the agglomeration of CaCO\({}_{3}\) particles. The laser diffraction analysis (Figure 5) highlights that the CaCO\({}_{3}\) powder sample predominantly consists of very fine particles, mostly of sizes less than 100 \(\upmu\)m. The decrease in volume percentage beyond this size range signifies a lack of substantially larger particles, indicating a highly fine and uniform PSD. At 1000\(\times\) magnification, Figure 6 reveals a relatively homogenous distribution of calcium carbonate particles with a noticeable degree of agglomeration. The particles appear to form loosely bound clusters, which is typical in fine particulate systems due to the inherent cohesive forces at the nanoscale. At a higher magnification of 5000\(\times\), the finer details of the individual calcium carbonate particles become evident.