Nanomaterials and printing techniques for 2D and 3D soft electronics

Abstract

The merging of electronically conductive elements with soft polymeric materials gave birth to the novel field of soft and stretchable electronics and robotics, where the key aspect is the maintenance of the electrical properties even under severe mechanical deformation. Here we review the variety of fabrication techniques that have been designed, studied and tested, leading to foresee how soft technologies can have a revolutionary impact in the progress of biomedicine and pre-clinical practice, wearable electronics, environmental monitoring and recognition, smart farming and precision agriculture, energy harvesting and storage. A particular focus is given to wet and dry techniques for 2D and 3D printed electronics that allow the coupling of compliant conductive elements on complex three-dimensional objects and platforms. We discuss how a selection and a targeted optimization amongst different nanoscale building blocks nanomaterials and deposition techniques are now necessary. The watchwords to be prioritized are scalability, versatility, environmental sustainability and biocompatibility, integration and reduction of the fabrication steps. The target is the design of an eco-friendly and versatile approach for the full additive manufacturing of free-form advanced soft electronic devices, eventually biocompatible and biodegradable, with a multi-layer and multi-material process able to print both active and passive 3D elements on soft polymeric platforms. The sequential combination of dry and wet spray printing shows to be one of the most promising approach.

Let’s Print an Ecology in 3D (and 4D)

“…Applying 3D printing technologies opens up new possibilities for smart farming and precision agriculture, such as increased nutrition value of final products, reducing food wastage [102]. Robots based on 3D printer ideas can seed plants, kill weeds, sense soilmoisture content, and irrigate plants individually over raised bed areas [103]; the design of eco-friendly advanced soft electronic devices (biocompatible and biodegradable) allows for environmental monitoring (sensors for measuring soil moisture level and temperature), grippers used in harvesting the crops, artificial lighting control, and energy harvesting and storage [26,104,105]. Since every material, product, and production process has an ecological impact, 3D printing studies often involve the Life Cycle Assessment of prototypical printing to establish a point of comparison to the environmental impact [106][107][108].…”

Electromechanical characterization and computational analysis of the corona-enabled electrostatic printed flexible strain sensors

“…However, these techniques have limitations in efficiency and applicability when applied to soft electronics, as many of the current PSEs require a passive polymer binder for material transfer 1,6 such as increased drying time and low melting temperature of polymer additives, which may increase manufacturing time and costs and limit material options 1 . To eliminate the need for passive polymer binders during fabrication and advance the design of PSEs, this study investigates a novel manufacturing technique, namely corona-enabled electrostatic printing (CEP) 1 .…”

Super-Stretchable Resistive Strain Sensor Based on Ecoflex–Gold Nanocomposites

“…35 The incorporation of metallic clusters with the polymer surface by supersonic cluster beam deposition (SCBD) has been demonstrated as an effective alternative to the fabrication of soft and stretchable electric conductive structures. 36 SCBD is a fabrication technology where neutral metallic clusters are supersonically accelerated in a carrier beam of inert gas toward a substrate of choice. 37 Because of their kinetic energy, clusters can penetrate the surface of soft polymeric materials gradually forming percolating network of conductive nanoparticles.…”