Bicomponent Cellulose Fibrils and Minerals Afford Wicking Channels Stencil-Printed on Paper for Rapid and Reliable Fluidic Platforms

Abstract

Flexible and easy-to-use microfluidic systems are suitable options for point-of-care diagnostics. Here, we investigate liquid transport in fluidic channels produced by stencil printing on flexible substrates as a reproducible and scalable option for diagnostics and paper-based sensing. Optimal printability and flow profiles were obtained by combining minerals with cellulose fibrils of two different characteristic dimensions, in the nano- and microscales, forming channels with ideal wettability. Biomolecular ligands were easily added by inkjet printing on the channels, which were tested for the simultaneous detection of glucose and proteins. Accurate determination of clinically relevant concentrations was possible from linear calibration, confirming the potential of the introduced paper-based diagnostics. The results indicate the promise of simple but reliable fluidic channels for drug and chemical analyses, chromatographic separation, and quality control.

Immobilized cellulose nanospheres enable rapid antigen detection in lateral flow immunoassays

“…To prepare porous substrates for immunoassays, fluidic channels were stencil printed on PowerCoat® paper supports according to our previously reported method (Solin et al 2021 ). Briefly, a Ca-CH paste was prepared by mixing CaCO 3 , CNF, and HefCel in DI water (dry weight ratio 95:2.5:2.5), and propylene glycol (5 wt% of the wet paste) was also added.…”

“…Supports that facilitate sensitive and rapid detection also need consideration. As an alternative to paper-based substrates, we have developed printable wicking materials comprising calcium carbonate particles and micro- and nanocellulose binders that are stencil-printed on flexible paper or polymer substrates, forming fluidic channels (Solin et al 2021 ). These printable pastes allow tunable and complex flow channel designs.…”

Immobilized cellulose nanospheres in lateral flow immunoassay enable rapid nucleocapsid antigen-based diagnosis of SARS-CoV-2 from salivary samples

“…To prepare porous substrates for immunoassays, fluidic channels were stencil printed on PowerCoat ® paper supports according to our previously reported method 29 . Briefly, a stencil-printable paste was prepared by mixing CaCO3, CNF, and HefCel.…”

“…Paper-based fluidic systems may also lack pattern resolution and the complexity of the channel design can be limited 27,28 . As an alternative for paperbased substrates, we have developed printable wicking materials comprising calcium carbonate particles and micro-and nanocellulose binders that are stencil-printed on flexible paper or polymer substrates, forming fluidic channels 29 . These printable pastes allow tunable and complex flow channel designs.…”

“…The fluid wicking properties of these channels have been analyzed in our previous work, where we reported that the channels wicked 4 cm of water in approx. 130 s29 . In addition, SEM images of the channel surfaces showed a porous network formed by the cubic-shaped inorganic filler and cellulose micro-and nanofibrils, sued as binders, FigureS6.…”