Fabricating Stretchable Paper-Based Substrates with a Core-Sheath Structure for Papertronics

When and Where

Nov 28, 2022
8:00pm - 10:00pm

Hynes, Level 1, Hall A

Presenter

Joab Dorsainvil

Co-Author(s)

Joab Dorsainvil¹

Binghamton University, The State University of New York¹

Abstract

Joab Dorsainvil¹

Binghamton University, The State University of New York¹

Introduction: Paper-based bioelectronics, papertronics is an emerging technology for next-generation sensing and energy storage due to its significant material properties; including high surface-to-volume ratio, porous structure, biocompatibility, biodegradability, low-cost availability, foldability, and lightweight composition [1]. However, due to the intrinsic mechanical properties of cellulose, these stiff mechanics create undesirable substrates for stretchable bioelectronics. As a result, papertronics demonstrate limited conformability to the complex microarchitecture of skin and fail to exhibit deformation mechanics required to address the mechanical mismatch between rigid electronics and skin. To bridge the gap between papertronics and electronics skin (e-skin), herein we studied engineering strategies to exploit the material, chemical, and physical properties of paper (cellulose acetate or cellulose) amalgamated with the soft mechanics of a silicone elastomer (e.g., Dupont Liveo Soft Skin Adhesives) through coaxial electrospinning. The core-sheath silicone elastomer-cellulose acetate fibers mimic the extracellular matrix of human skin while maintaining the chemical surface properties of paper, enabling the integration of electronic components with existing manufacturing and printing techniques. Materials and Methods: Cellulose acetate (CA) (MW = 30,000) and organic solvents (e.g., THF, DMF, Acetone) were purchased from Sigma Aldrich. The 7-9700 soft skin silicone adhesive (SSA) was gifted from DuPont. We used a coaxial needle with an electrospinning unit (MSK-NFES-3; MTI Corporation, CA) to create the fibrous mats while systematically testing operational parameters (e.g., feed rate, applied voltage, polymer concentration, etc.). Scanning electron microscopy (SEM) and confocal microscopy was used to analyze fiber alignment and core-sheath structure. Fiber diameter was measured with the utilization of ImageJ. Mechanical properties of the engineered fiber mat were evaluated by tensile testing with a 5 N load cell at a 5.10 mm sec-1 strain rate. Fourier transform infrared (FTIR) spectroscopy and Electron Dispersive Spectroscopy (EDS) determined the chemical and elemental characteristics of the fabricated stretchable papers. Results and Discussion: SEM confirmed a fibrous structure of the fiber mat with an average fiber diameter of 1.38 ± 0.37 µm (n=250). Confocal microscopy revealed the core-sheath structure of the SSA core (blue) and CA sheath (red) via coaxial electrospinning. Energy dispersive spectroscopy (EDS) identified elemental peaks that reflect a core-sheath structure of an individual SSA-CA fiber. Using this stretchable paper, we were able to develop a microbial fuel cell by stacking three stretchable papers as an anode, membrane, and cathode material, which generated a max power output of 10.5 µW in PBS. Conclusions: The coaxial structure of cellulose acetate and soft skin adhesive improves the stretchability of paper substrates up to 45% strain which is greater than the stretchability of conventional paper substrates (< 2%). Fabricating an MFC device using our stretchable paper demonstrates fabrication processing compatibility of these materials and thus shows the potential for future application in various ranges of papertronics while also sharing characteristics from soft bioelectronics. Acknowledgments: This research is supported by the National Science Foundation (NSF; ECCS#2020486). We thank DuPont for donating the SSA elastomer. Reference: [1] Martinez, A, W et al. Angewandte Chemie (2007) 46 (8), 1318-20.