skip to main content

This content will become publicly available on November 3, 2024

Title: Dry-Printing Conductive Circuit Traces on Water-Soluble Papers
Printed electronics are gaining significant interest due to their design flexibility, low fabrication cost, and rapid design-to-manufacturing turnaround. Conventional substrates for printed electronics are often based on nonbiodegradable polymers such as polyimide that pose high environmental challenges by creating massive e-waste and pollution. As the demand for printed electronics and sensors increases, the ability to print such devices on biodegradable substrates can provide a solution to such environmental problems. However, current printing technologies are based on liquids and inks that are incompatible with biodegradable substrates, such as paper. Here, we present a dry-printing process, namely, a dry additive nanomanufacturing (Dry-ANM) technique, for printing conductive silver lines and patterns on biodegradable papers for flexible hybrid papertronics. Pure and dry nanoparticles are generated by pulsed laser ablation of a silver target that is then transported through a nozzle and directed onto paper substrates, where they are deposited and laser-sintered in real time to form the desired pattern without damaging the paper. The effects of different printing parameters on the paper-burning threshold are investigated, and the electrical properties of the lines are characterized by using different line thicknesses and sintering laser power densities. In addition, the mechanical and electrical properties of the printed lines and patterns are evaluated by bending and twisting tests. Furthermore, the feasibility of printing silver on different paper types is demonstrated. This research can potentially lead to biodegradable and environmentally friendly printed electronics and sensors.  more » « less
Award ID(s):
2134024 2018794
Author(s) / Creator(s):
; ; ; ; ; ; ; ;
Publisher / Repository:
ACS Publications
Date Published:
Journal Name:
ACS Sustainable Chemistry & Engineering
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    The growing demand for flexible and wearable hybrid electronics has triggered the need for advanced manufacturing techniques with versatile printing capabilities. Complex ink formulations, use of surfactants/contaminants, limited source materials, and the need for high‐temperature heat treatments for sintering are major issues facing the current inkjet and aerosol printing methods. Here, the nanomanufacturing of flexible hybrid electronics (FHE) by dry printing silver and indium tin oxide on flexible substrates using a novel laser‐based additive nanomanufacturing process is reported. The electrical resistance of the printed lines is tailored during the print process by tuning the geometry and structure of the printed samples. Different FHE designs are fabricated and tested to check the performance of the devices. Mechanical reliability tests including cycling, bending, and stretching confirm the expected performance of the printed samples under different strain levels. This transformative liquid‐free process allows the on‐demand formation and in situ laser crystallization of nanoparticles for printing pure materials for future flexible and wearable electronics and sensors.

    more » « less
  2. The reliability of additively manufactured flexible electronics or so-called printed electronics is defined as mean time to failure under service conditions, which often involve mechanical loads. It is thus important to understand the mechanical behavior of the printed materials under such conditions to ensure their applicational reliability in, for example, sensors, biomedical devices, battery and storage, and flexible hybrid electronics. In this article, a testing protocol to examine the print quality of additively nanomanufactured electronics is presented. The print quality is assessed by both tensile and electrical resistivity responses during in-situ tension tests. A laser based additive nanomanufacturing method is used to print conductive silver lines on polyimide substrates, which is then tested in-situ under tension inside a scanning electron microscope (SEM). The surface morphology of the printed lines is continuously monitored via the SEM until failure. In addition, the real-time electrical resistance variations of the printed silver lines are measured in-situ with a multimeter during tensile tests conducted outside of the SEM. The protocol is shown to be effective in assessing print quality and aiding process tuning. Finally, it is revealed that samples appearing identical under the SEM can have significant different tendencies to delaminate. 
    more » « less
  3. There has been an increasing need of technologies to manufacturing chemical and biological sensors for various applications ranging from environmental monitoring to human health monitoring. Currently, manufacturing of most chemical and biological sensors relies on a variety of standard microfabrication techniques, such as physical vapor deposition and photolithography, and materials such as metals and semiconductors. Though functional, they are hampered by high cost materials, rigid substrates, and limited surface area. Paper based sensors offer an intriguing alternative that is low cost, mechanically flexible, has the inherent ability to filter and separate analytes, and offers a high surface area, permeable framework advantageous to liquid and vapor sensing. However, a major drawback is that standard microfabrication techniques cannot be used in paper sensor fabrication. To fabricate sensors on paper, low temperature additive techniques must be used, which will require new manufacturing processes and advanced functional materials. In this work, we focus on using aerosol jet printing as a highresolution additive process for the deposition of ink materials to be used in paper-based sensors. This technique can use a wide variety of materials with different viscosities, including materials with high porosity and particles inherent to paper. One area of our efforts involves creating interdigitated microelectrodes on paper in a one-step process using commercially available silver nanoparticle and carbon black based conductive inks. Another area involves use of specialized filter papers as substrates, such as multi-layered fibrous membrane paper consisting of a poly(acrylonitrile) nanofibrous layer and a nonwoven poly(ethylene terephthalate) layer. The poly(acrylonitrile) nanofibrous layer are dense and smooth enough to allow for high resolution aerosol jet printing. With additively fabricated electrodes on the paper, molecularly-functionalized metal nanoparticles are deposited by molecularly-mediated assembling, drop casting, and printing (sensing and electrode materials), allowing full functionalization of the paper, and producing sensor devices with high surface area. These sensors, depending on the electrode configuration, are used for detection of chemical and biological species in vapor phase, such as water vapor and volatile organic compounds, making them applicable to human performance monitoring. These paper based sensors are shown to display an enhancement in sensitivity, as compared to control devices fabricated on non-porous polyimide substrates. These results have demonstrated the feasibility of paper-based printed devices towards manufacturing of a fully wearable, highly-sensitive, and wireless human performance monitor coupled to flexible electronics with the capability to communicate wirelessly to a smartphone or other electronics for data logging and analysis. 
    more » « less
  4. Abstract

    The generation of electronic waste (e‐waste) poses a significant environmental challenge, necessitating strategies to extend electronics’ lifespan and incorporate eco‐friendly materials to enable their rapid degradation after disposal. Foldable electronics utilizing eco‐friendly materials offer enhanced durability during operation and degradability at the end of their life cycle. However, ensuring robust physical adhesion between electrodes/circuits and substrates during the folding process remains a challenge, leading to interface delamination and electronic failure. In this study, electrohydrodynamic (EHD) printing is employed as a cost‐effective method to fabricate the eco‐friendly foldable electronics by printing PEDOT:PSS/graphene composite circuits onto polyvinyl alcohol (PVA) films. The morphology and electrical properties of the printed patterns using inks with varying graphene and PEDOT:PSS weight ratios under different printing conditions are investigated. The foldability of the printed electronics is demonstrated, showing minimal resistance variation and stable electronic response even after four folds (16 layers) and hundreds of folding and unfolding cycles. Additionally, the application of printed PEDOT:PSS/graphene circuit is presented as a resistive temperature sensor for monitoring body temperature and respiration behavior. Furthermore, the transient features and degradation of the PEDOT:PSS/graphene/PVA based foldable electronics are explored, highlighting the potential promise as transient electronics in reducing electronic waste.

    more » « less
  5. Abstract

    Direct printing of functional materials, structures, and devices on various platforms such as flexible to rigid substrates is of interest for applications ranging from electronics to energy and sensing to biomedical devices. Current additive manufacturing (AM) and printing processes are either limited by the available sources of functional materials or require to be in the form of precisely designed inks. Here, a novel laser‐based additive nanomanufacturing (ANM) system capable of in situ and on‐demand generations of nanoparticles that can serve as nanoscale building blocks for real‐time sintering and dry printing a variety of multifunctional materials and patterns at atmospheric pressure and room temperature is reported. The ability to print different functional materials on various rigid and flexible platforms is shown. This nonequilibrium process involves pulsed laser ablation of targets and in situ formation of pure amorphous nanoparticles’ stream that are guided through a nozzle onto the surface of the substrate, where they are sintered/crystallized in real‐time. Further, the process–structure relationship of the printed materials from nanoscale to microscale is shown. This new ANM concept opens up an opportunity for printing advanced functional materials and devices on rigid and flexible substrates that can be employed both on the earth and in space.

    more » « less