Highly Concentrated, Conductive, Defect-free Graphene Ink for Screen-Printed Sensor Application

Abstract

Highlights Ultrathin and defect-free graphene ink is prepared through a high-throughput fluid dynamics process, resulting in a high exfoliation yield (53.5%) and a high concentration (47.5 mg mL−1). A screen-printed graphene conductor exhibits a high electrical conductivity of 1.49 × 104 S m−1 and good mechanical flexibility. An electrochemical sodium ion sensor based on graphene ink exhibits an excellent potentiometric sensing performance in a mechanically bent state. Real-time monitoring of sodium ion concentration in sweat is demonstrated. Abstract Conductive inks based on graphene materials have received significant attention for the fabrication of a wide range of printed and flexible devices. However, the application of graphene fillers is limited by their restricted mass production and the low concentration of their suspensions. In this study, a highly concentrated and conductive ink based on defect-free graphene was developed by a scalable fluid dynamics process. A high shear exfoliation and mixing process enabled the production of graphene at a high concentration of 47.5 mg mL−1 for graphene ink. The screen-printed graphene conductor exhibits a high electrical conductivity of 1.49 × 104 S m−1 and maintains high conductivity under mechanical bending, compressing, and fatigue tests. Based on the as-prepared graphene ink, a printed electrochemical sodium ion (Na+) sensor that shows high potentiometric sensing performance was fabricated. Further, by integrating a wireless electronic module, a prototype Na+-sensing watch is demonstrated for the real-time monitoring of the sodium ion concentration in human sweat during the indoor exercise of a volunteer. The scalable and efficient procedure for the preparation of graphene ink presented in this work is very promising for the low-cost, reproducible, and large-scale printing of flexible and wearable electronic devices.

Nanomaterials for IoT Sensing Platforms and Point-of-Care Applications in South Korea

“…Low-dimensional nanomaterials such as 1D CNTs, 2D graphene, and 2D MXenes are gaining much attention owing to their high conductivity, large surface area, flexibility, and durability [144][145][146]. Recently, a screen-printed wearable Na + sensor based on a conductive graphene ink transducer with high electrical conductivity was integrated with a wristwatch-type device [147]. To prepare graphene ink, exfoliated graphene (ex-Gr) was synthesized by the fluid dynamics-induced exfoliation and mixing process, resulting in a defect-free ex-Gr with high yield (Figure 11a).…”

Self-Exfoliation of Flake Graphite for Bioinspired Compositing with Aramid Nanofiber toward Integration of Mechanical and Thermoconductive Properties

“…Graphene-based composites have made substantial progress in the past decade, and their thermal conductivity enhancement depends largely on graphene exfoliation and the co-assembly of graphene with polymers. For graphene exfoliation, liquid-based direct delamination strategies are widely used, such as ultrasonication [14,15], high-shear mixing [16][17][18] and ball milling [19,20]. The delamination is achieved by overcoming the van der Waals attraction within bulk graphite through the shear force generated between graphite and collapsed cavitation bubbles, mixing head, or grinding ball, avoiding the formation of basal-plane defects [21].…”

Morphology and Chemical Purity of Water Suspension of Graphene Oxide FLAKES Aged for 14 Months in Ambient Conditions. A Preliminary Study

“…Graphene is a two-dimensional, one-atom-thick layer of carbon, in which atoms are oriented in a hexagonal crystal lattice. The promising and appealing properties of graphene-based materials are widely used in many research-oriented fields, like fuel cells [ 1 , 2 ], batteries [ 3 , 4 ], screens [ 5 , 6 ], sensors [ 7 , 8 ], flexible electronics [ 9 , 10 ], tissue engineering [ 11 , 12 ], and membranes [ 13 , 14 ]. Moreover, their unique features result in an increase of materials’ mechanical strength, electrical and thermal conductivity, and surface area and flexibility [ 15 , 16 , 17 ], making them the most preferred choice in experimental procedures.…”