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In this paper, we present high-performance and versatile inkjet-printed paper photo-actuators based on two-dimensional (2D) nanomaterials. As a rapid fabrication method, inkjet printing of 2D materials is used to promptly fabricate photo-actuators in a bi-layer paper/polymer structure. Water-based and biocompatible inks based on graphene and molybdenum disulfide are developed based on liquid phase exfoliation and differential centrifugation technique. It is shown that incorporation of 2D materials with inkjet printing techniques and liquid phase exfoliation can lead to rapid fabrication of photo-actuators with huge opto-mechanical energy release and versatility with a broad range of applications due to specific design and methods presented in this paper. [ABSTRACT FROM AUTHOR]

The functionalities of a paper-PDMS hybrid microchannel, as a potential fluidic transport platform, are presented. The setup consists of a PDMS microchannel with one of its walls covered by paper. In contrast to the available microfluidic platforms, the capillary filling is found to occur at much faster speed in the hybrid channel. Moreover, experimentation using two dye solutions shows mixing enhancement at a significantly faster rate and at a shorter distance in the hybrid channel as compared to the other available counterparts. The paper attachment is found to induce an effective slip during liquid transport, and thereby allows faster transport and capillary filling. The liquid slippage further modifies the shear flow behavior near the wall leading to a slip-enhanced mixing within the hybrid channel. These fundamental understandings correspond to the experimental results quantitatively in terms of corroborating scaling laws. Further mixing enhancement is introduced through spiral, curved and elliptical–spiral geometries of the channel. Apart from the above benefits, the enclosed arrangement protects sensitive reagents from external environment and offers better control over their transport, thus giving a stable mixing and reaction performance inside the channel. [ABSTRACT FROM AUTHOR]

A commercially available Janus paper with one hydrophobic (polyethylene-coated) face and a hygroscopic/hydrophilic one is irreversibly bonded to a polydimethylsiloxane (PDMS) substrate incorporating microfluidic channels via corona discharge surface treatment. The bond strength between the polymer-coated side and PDMS is characterized as a function of corona treatment time and annealing temperature/time. A maximum strength of 392 kPa is obtained with a 2 min corona treatment followed by 60 min of annealing at 120 °C. The water contact angle of the corona-treated polymer side decreases with increased discharge duration from 98° to 22°. The hygroscopic/hydrophilic side is seeded with human lung fibroblast cells encapsulated in a methacrylated gelatin (GelMA) hydrogel to show the potential of this technology for nutrient and chemical delivery in an air–liquid interface cell culture. [ABSTRACT FROM AUTHOR]