Binder-free printed PEDOT wearable sensors on everyday fabrics using oxidative chemical vapor deposition

Abstract

Polymeric sensors on fabrics have vast potential toward the development of versatile applications, particularly when the ready-made wearable or fabric can be directly coated. However, traditional coating approaches, such as solution-based methods, have limitations in achieving uniform and thin films because of the poor surface wettability of fabrics. Herein, to realize a uniform poly(3,4-ethylenedioxythiophene) (PEDOT) layer on various everyday fabrics, we use oxidative chemical vapor deposition (oCVD). The oCVD technique is a unique method capable of forming patterned polymer films with controllable thicknesses while maintaining the inherent advantages of fabrics, such as exceptional mechanical stability and breathability. Utilizing the superior characteristics of oCVD PEDOT, we succeed in fabricating blood pressure-and respiratory rate-monitoring sensors by directly depositing and patterning PEDOT on commercially available disposable gloves and masks, respectively. Those results are expected to pave efficient and facile ways for skin-compatible and affordable sensors for personal health care monitoring.

Smart textiles for human–machine interface fabricated via a facile on-site vapor-phase polymerization

“…This bridging structure caused by the oxidant film tends to lead the VPP process to form a different surface topography on the substrate than the oxidative chemical vapor deposition (oCVD) method. 39,57 We assumed that the film of the oxidant on the surface of the yarn with a dense and braided structure caused the monomers deposited in the early stage of the reaction to act as a shielding layer, hindering the diffusion of the monomers into the yarn, so that the deposition layer tended to form a conformal coating on the single strand rather than a single fiber. Generally, the VPP process appeared to allow PEDOT functionalization of a variety of commonly used yarns.…”

“…38 Besides the effect of aqueous solution, the weak adhesion of polymers to textiles is another reason for the deterioration of a textile's properties. 32,39 Some additives have been used to improve the adhesion between PEDOT:PSS and fabrics, but most of these additives are insulating and can negatively affect the breathability and comfort of the fabrics. 40…”

Review on PEDOT:PSS-Based Conductive Fabric

“…Textiles such as polyethylene terephthalate (PET) (see Figure ), woven Spandex fibers, cotton, and polyurethane nonwoven fibers can benefit from these processes. In addition, chemical vapor deposition , and plasma treatment techniques have been used to develop uniform layers of conductive polymers on the fiber surface. Another method to create uniform layers of conductive polymers on the fiber surface is in situ polymerization of conjugated polymer systems on the surface of the textile fiber. − Similar to the methods listed below, this technique can be used to produce flexible and lightweight fabrics with good conductivity.…”

Robust and Highly Conductive PEDOT:PSS:Ag Nanowires/Polyethyleneimine Multilayers Based on Ionic Layer-by-Layer Assembly for E-Textiles and 3D Electronics

“…Poly­(3,4-ethylenedioxythiophene):poly­(styrenesulfonate) (PEDOT:PSS) with high stability and solution processibility has various practical applications, including in sensing devices, − wearable electronics, − and optoelectronic systems. − The pristine PEDOT:PSS film prepared using simple free-standing casting has an electrical conductivity of less than 1 S cm –1 . − The conductivity is substantially increased by applying a mixture of a PEDOT:PSS solution and highly conductive fillers, such as metal nanowires (∼2000 S cm –1 ; hereafter, the conductivity values refer to the values of the resulting PEDOT:PSS composite films), − graphene (638 S cm –1 ), , and carbon nanotubes (∼1065 S cm –1 ). − As a second option, the conductivity can be improved by additional mixing with nonconductive materials, such as ethylene glycol (>443 S cm –1 ), , dimethyl sulfoxide (>979 S cm –1 ), − methanol (1362 S cm –1 ), dimethyl sulfate (132 S cm –1 ), D-sorbitol (>1000 S cm –1 ), Triton X-100 (72 S cm –1 ), and ionic liquids (>2084 S cm –1 ) , to induce the phase separation of PEDOT and PSS and thereby more crystallized domains of PEDOT chains and remove excessive PSS, resulting in effective conductive three-dimensional (3D) networks. Treatment with a strong acid (i.e., H 2 SO 4 solution) also exerts a similar effect, increasing the conductivity to over 3000 S cm –1 . − …”