# Microscale Computed Tomography (μCT) Imaging of Leak Pathways for Optimized Leak-Free 3D Printed Fluidics

## TL;DR

This paper uses μCT imaging to identify why 3D printed fluidic devices leak and shows how to optimize printing settings to prevent leaks while saving time and cost.

## Contribution

The study reveals that channel wall quality—not infill level—is critical for preventing leaks in 3D printed fluidics.

## Key findings

- Smaller layer heights and increased flow rates improve channel wall formation and prevent leaks.
- Reducing infill can save over 50% in print time and material costs without compromising performance.

## Abstract

3D printing is a highly attractive method for manufacturing
micro-
and millifluidic devices due to fast fabrication times and a low barrier
to entry. Of the common 3D printing methods, fused filament fabrication
(FFF) is the most accessible but is also susceptible to leakages when
using default printer settings. Here, we combine microscale computed
tomography (μCT) X-ray imaging with bulk leak testing to understand
the fundamental structural reasons why leakages occur, and the effect
of optimizing print parameters. In contrast to previous recommendations,
we show that the amount of infill can be reduced as required, with
print bodies being intrinsically porous, regardless of infill. Instead,
we find that it is solely the channel wall quality that determines
whether leaks will occur. In keeping with previous reports, we see
that smaller layer heights (<0.1 mm) and increased flow rates (>100%
compared to the recommended rate) are key to preventing leakage, and
show this is because of their positive effect on channel wall formation.
A key consequence of being able to maintain channel integrity while
using low infill values is that print times and material costs can
be greatly reduced (over 50% time and cost savings for the test pieces
used here) without compromising device performance.