Printed Stretchable Graphene Conductors for Wearable Technology

Abstract

Skin-compatible printed stretchable conductors that combine a low gauge factor with a high durability over many strain cycles are still a great challenge. Here, a graphene nanoplatelet-based colloidal ink utilizing a skin-compatible thermoplastic polyurethane (TPU) binder with adjustable rheology is developed. Stretchable conductors that remain conductive even under 100% strain and demonstrate high fatigue resistance to cyclic strains of 20–50% are realized via printing on TPU. The sheet resistances of these conductors after drying at 120 °C are as low as 34 Ω □ –1 mil –1 . Furthermore, photonic annealing at several energy levels is used to decrease the sheet resistance to <10 Ω □ –1 mil –1 , with stretchability and fatigue resistance being preserved and tunable. The high conductivity, stretchability, and cyclic stability of printed tracks having excellent feature definition in combination with scalable ink production and adjustable rheology bring the high-volume manufacturing of stretchable wearables into scope.

Screen-printed graphene tailoring the amplitude of guided wave in the rectangular waveguide for millimeter wave applications

“…Actually, the fabricated screen-printed graphene basically shows no thickness variation. The sheet resistance variation is well below 10 % and only on two sides of the graphene as we measured in our previous work [27,39,40]. So, the variation of modulation depth caused by the non-uniformity of thickness and sheet resistance is much less than 0.5 dB.…”

“…In this manuscript, the focus is on the simulation component and on its validation, which requires printed lines with optimal uniformity of thickness and sheet resistance, as we have selected. The printing part has been thoroughly explored and optimized in previous work already published [27,39,40].…”

Advances in Functionalized Applications of Graphene‐Based Wearable Sensors in Healthcare

“…[ 118 ] Another fabrication technique was used on photographic paper for the application of a fully inkjet‐printed gas sensor matrix, which demonstrated excellent stability and flexibility under various bending and long‐term dynamic sensing tests. [ 120 ] Other amazing works on inkjet printing include the combination of inkjet printing for healthcare and wearable devices, [ 121 ] the development of stretchable graphene conductors for wearable technology, [ 122 ] and so on. Wearable sweat sensors have the potential to advance precision medicine by collecting health‐related molecular data in a non‐invasive manner.…”

Engineering of graphene-based composites with hexagonal boron nitride and PEDOT:PSS for sensing applications

“…Due to their attractive advantages of small weight, portability, conformity, and comfort, flexible electronics has made great progress in theory and application in recent years. [1][2][3] The rapid development of flexible wearable electronics has led to the expansion of its engineering applications in health monitoring. 4,5 In this field, sensors are used to convert physiological signals into electrical signals for analysis of sweat, joint flexion, blood pressure, heart rate, and so on.…”