3D Printing of Monolithic Capillarity‐Driven Microfluidic Devices for Diagnostics

Abstract

Rapid diagnostic testing at the site of the patient is essential when a fully equipped laboratory is not accessible. To maximize the impact of this approach, low‐cost, disposable tests that require minimal user‐interference and external equipment are desired. Fluid transport by capillary wicking removes the need for bulky ancillary equipment to actuate and control fluid flow. Nevertheless, current microfluidic paper‐based analytical devices based on this principle struggle with the implementation of multistep diagnostic protocols because of fabrication‐related issues. Here, 3D‐printed microfluidic devices are demonstrated in a proof‐of‐concept enzyme‐linked immunosorbent assay in which a multistep assay timeline is completed by precisely engineering capillary wetting within printed porous bodies. 3D printing provides a scalable route to low‐cost microfluidic devices and obviates the assembly of discrete components. The resulting rapid and seamless transition between digital data and physical objects allows for rapid design iterations, and opens up perspectives on distributed manufacturing.

3D Printing Technologies in Biosensors Production: Recent Developments

“…In addition to the most common 3D printing techniques used in biosensing, such as material extrusion, vat photopolymerization, and material jetting, in the literature we can find further examples of 3D printing technology applications, mainly for diagnostic biosensor manufacturing [57,58]. Binder jetting (BJ), also known as the powder bed technique, is one of the technologies recognized by the ASTM standard.…”

“…Therefore, the post-printing reinforcement process is necessary; some materials are generally involved, such as melted wax, cyanoacrylate glue, or epoxy resin [80]. Achille et al [57] utilized this technology to fabricate a 3D-printed microfluidic diagnostic device; particularly, up to five different binders can be printed at the same time, starting from poly(methyl methacrylate) powder as building material with an average size of 50 µm. The 3D capillarity microfluidic devices obtained from polymethyl methacrylate (PMMA) showed a high porosity when manufactured through BJ; the interstitial space was obtained during the evaporation process of the binder inside the construct.…”

Microfluidic Chain Reaction

“…[8][9][10][11] Capillary microfluidics integrate energy supply and flow control onto a single chip by using capillary phenomena, but programmability remains rudimentary with at most a handful (eight) operations possible. [12][13][14][15][16][17][18][19] Here we introduce mesoscopic microfluidic chain reactions (MCRs) based on capillary phenomena for reliable programming and automation of complex liquid handling algorithms integrated in a chip. MCRs are encoded into the chip microarchitecture, 3D printed as a monolithic circuit, and deterministically propagated by the free-energy of a paper pump.…”

Microfluidic Chain Reaction: Conditional, Structurally Programmed Propagation of Capillary Flow Events

“…[8][9][10][11] Capillary microfluidics integrate energy supply and flow control onto a single chip by using capillary phenomena, but programmability remains rudimentary with at most a handful (eight) operations possible. [12][13][14][15][16][17][18][19] Here we introduce the microfluidic chain reaction (MCR) as the conditional, structurally programmed propagation of capillary flow events. Monolithic chips integrating a MCR are 3D printed, and powered by the free-energy of a paper pump, autonomously execute liquid handling algorithms step-by-step.With MCR, we automated (i) the sequential release of 300 aliquots across chained, interconnected chips, (ii) a protocol for SARS-CoV-2 antibodies detection in saliva, and (iii) a thrombin generation assay by continuous subsampling and analysis of coagulation-activated plasma with parallel operations including timers, iterative cycles of synchronous flow and stopflow operations.…”

“…[8][9][10][11] Capillary microfluidics integrate energy supply and flow control onto a single chip by using capillary phenomena, but programmability remains rudimentary with at most a handful (eight) operations possible. [12][13][14][15][16][17][18][19] Here we introduce the microfluidic chain reaction (MCR) as the conditional, structurally programmed propagation of capillary flow events. Monolithic chips integrating a MCR are 3D printed, and powered by the free-energy of a paper pump, autonomously execute liquid handling algorithms step-by-step.…”