Three-dimensional (3D) printing has emerged as a potential revolutionary technology for the fabrication of microfluidic devices. A direct experimental comparison of the three 3D printing technologies dominating microfluidics was conducted using a Y-junction microfluidic device, the design of which was optimized for each printer: fused deposition molding (FDM), Polyjet, and digital light processing stereolithography (DLP-SLA). Printer performance was evaluated in terms of feature size, accuracy, and suitability for mass manufacturing; laminar flow was studied to assess their suitability for microfluidics. FDM was suitable for microfabrication with minimum features of 321 ± 5 μm, and rough surfaces of 10.97 μm. Microfluidic devices >500 μm, rapid mixing (71% ± 12% after 5 mm, 100 μL/min) was observed, indicating a strength in fabricating micromixers. Polyjet fabricated channels with a minimum size of 205 ± 13 μm, and a surface roughness of 0.99 μm. Compared with FDM, mixing decreased (27% ± 10%), but Polyjet printing is more suited for microfluidic applications where flow splitting is not required, such as cell culture or droplet generators. DLP-SLA fabricated a minimum channel size of 154 ± 10 μm, and 94 ± 7 μm for positive structures such as soft lithography templates, with a roughness of 0.35 μm. These results, in addition to low mixing (8% ± 1%), showed suitability for microfabrication, and microfluidic applications requiring precise control of flow. Through further discussion of the capabilities (and limitations) of these printers, we intend to provide guidance toward the selection of the 3D printing technology most suitable for specific microfluidic applications.

3D printing technology is now frequently employed in many areas of research and development. However, a relatively narrow range of 3D printable materials with a limited spectrum of physico-chemical properties still restricts the true potential of this potentially disruptive technology. There is rapidly increasing interest in the improvement and diversification of properties of generic printing materials via the introduction of fillers with unique properties, and/or by blending materials exhibiting different properties to generate high performance composites. 3D printed composites have already been utilised in a wide range of applications, including biomedical, mechanical, electrical, thermal and optically enhanced products. The increasing popularity of 3D printed composites can be attributed to the ability to fabricate complex geometries, low cost production, and other advantages associated with rapid prototyping. This review covers all the recent reports in which the properties of generic 3D printable materials have been modified either by adding nanoparticles, fibers, other polymers, or by a chemical reaction for fabrication of composites with enhanced biomaterial, mechanical, electrical, thermal, optical and other properties.

A solid phase extraction (SPE) method has been developed and applied in conjunction with a previously reported liquid chromatography tandem mass spectrometry (LC–MS–MS) procedure for the determination of illicit drugs and abused pharmaceuticals in treated wastewater and surface water samples at the ng L⁻¹ level. A full method validation was also performed and determined levels of analytical sensitivity were found to lie in the 1–10 ng L⁻¹ range using river water as a test sample matrix and a sample size of 500 mL. The developed procedure was successfully applied for the determination of the chosen analytes in wastewater treatment plants in Dublin, Ireland and rapidly expanding commuter towns in the surrounding counties. Cocaine was detected in 70% of the collected samples in the range of 25–489 ng L⁻¹, its primary metabolite, benzoylecognine (BZE) was also detected in the range of 22–290 ng L⁻¹. Other substances detected included morphine, Tempazepam and the primary metabolite of methadone.

A low cost 3D stereolithography based printer has been used for a new polymer composite material with enhanced thermal properties containing 30 wt% micro-particulate diamond.