We have designed multiple versions of this PDMS mold, some with a single inlet but multiple parallel channels, and some with different inlets for using either syringes or tubing. All the designs are available as Supplementary Material. For the first test, we flushed a suspension of microspheres in water. The microfluidic captured and size-sorted the microparticles as they were captured in different steps of the device. The SLA printing technique of the mold creates a surface roughness of a few microns, as seen in the SEM image (Figure ); the roughness may help capture particles of the same size of the steps themselves. This effect can be seen in Figure (bottom), where some particles are stuck not on the edge of the step but between two steps. Another important factor to consider is the flexibility of PDMS. The higher the pressure applied in the channel, the more PDMS will deform, letting particles bigger than the single step to pass through. This can be minimized by reducing the lateral size of the channel. Smaller channels need more pressure to be deformed.