Experimental Investigation and Modeling of Three-Phase, Conductive, Cellulose-Based Paper
Paper-based electronics are emerging as lightweight, recyclable, and low-cost options for advanced mechanical, chemical, and electrical sensing. As one potential application of papertronics, paper-based skins may be capable of sensing touch, temperature, pressure, and humidity on synthetic or natural surfaces. Current paper-based skins mostly use paper as passive platforms to support conductive coatings or still rely on multiple layers to function. Here we use the morphology of paper for more than a carrier substrate or insulating dielectric to develop a functional sensing unit by itself.
In this work, we developed and fabricated conductive cellulose-based paper with embedded carbon black (CB) particles to detect pressure. Our composite paper showed stable piezoresistive responses within a broad pressure range from 1 kPa up to 5.5 MPa for 800 cycles. The piezoresistive sensitivities of our composite paper were concentration-dependent and decreased with pressure. A paper-based composite with 7.5 wt% CB had sensitivities of −0.514 kPa−1 over applied pressures ranging from 1 kPa to 50 kPa and −0.215 kPa−1 from 1 kPa to 250 kPa.
There are few theoretical models that capture piezoresistive responses of three-phase conductive composites. To interpret the electromechanical coupling of our piezoresistive composite, we proposed a computational model to capture the influence of the stochastic fibrous network. In this model, we randomly generated CB particles on a representative segment of fiber and used a depth-first-searching algorithm to establish networks of conductive paths to determine the bulk conductivity of fibers. Applying this derived conductivity of fibers to the stochastic fibrous network, we simulated the compression to investigate the effects of CB concentration, the porosity of paper, and degree of network compression on the piezoresistive sensitivity of the composites. The results of the simulation suggest that CB concentration and porosity of paper are critical parameters that give rise to nonlinear piezoresistive behavior in the composite paper.
We also employed hierarchical models with finite element analysis to validate the computational model. In this analysis, we approximated CB particles as circles with two layers and their aggregates as ellipses on a representative surface area of a fiber. The outer layer of CB represented the region where tunneling occured between particles and had lower conductivity than the inner layer. We investigated the combined effects of geometric parameters and the distribution of CB aggregates on the conductivity of fibers. Building the stochastic organization of fibers into a sheet of paper, we applied mechanical deformation to the fibrous network to simulate the compressing process. The finite element analysis showed similar piezoresistive characteristics as the computational model.
Experimental Investigation and Modeling of Three-Phase, Conductive, Cellulose-Based Paper
Category
Poster Presentation
Description
Session: 16-01-01 National Science Foundation Posters - On Demand
ASME Paper Number: IMECE2020-25350
Session Start Time: ,
Presenting Author: Tongfen Liang
Presenting Author Bio: I am a Ph.D. student in Mechanical Engineering in Rutgers University. Previously, I received my Bachelor of Engineering degree in Control and Instrumentation Technology and Master's degree in Mechanical Engineering from Beijing Jiaotong University.
My research area is paper-based electronics, with an emphasis on manufacturing and modelling of conductive composite paper.
Authors: Tongfen Liang Rutgers University
Meriem Akin Braunschweig University of Technology
Xiyue Zou Rutgers University
George Weng Rutgers University
Assimina PelegriRutgers University
Anna Root Rutgers University
Aaron Mazzeo Rutgers University