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Wearable electronics require thin and flexible substrate materials for user comfort. We propose a substrate material based on a nanocellulose-polyurethane matrix. The stretchability, i.e. Young's modulus and breaking strain, of the material can be tuned by nanocellulose concentration. We describe the fabrication process and demonstrate the modulation of the mechanical properties. Further, we present oxygen and water vapour permeability, as well as dielectric properties' measurements. Effects of substrate properties on printing of metallic conductors are considered. Laser cutting of the substrate and lamination of several layers of substrate material together are demonstrated, as well as hybrid integration of discrete components on the substrate. As an integrated demonstrator, a patch for local skin surface temperature measurement is presented. The patch thickness is 50μm, and it consists of two layers of the substrate material, printed metallic conductors and hybrid integrated temperature sensors.

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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.