TY - JOUR AU - Kim, Dong Seok AU - Jeong, Jae‑Min AU - Park, Hong Jun AU - Kim, Yeong Kyun AU - Lee, Kyoung G. AU - Choi, Bong Gill PY - 2021/03/08 Y2 - 2024/03/29 TI - Highly Concentrated, Conductive, Defect-free Graphene Ink for Screen-Printed Sensor Application JF - Nano-Micro Letters JA - Nano-Micro Lett VL - 13 IS - SE - Articles DO - 10.1007/s40820-021-00617-3 UR - https://nmlett.org/index.php/nml/article/view/853 SP - 87 AB - <p>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&nbsp;mg&nbsp;mL<sup>−1</sup> for graphene ink. The screen-printed graphene conductor exhibits a high electrical conductivity of 1.49 × 10<sup>4</sup> S m<sup>−1</sup> and maintains high conductivity under mechanical bending, compressing, and fatigue tests. Based on the as-prepared graphene ink, a printed electrochemical sodium ion (Na<sup>+</sup>) sensor that shows high potentiometric sensing performance was fabricated. Further, by integrating a wireless electronic module, a prototype Na<sup>+</sup>-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.</p><p>Highlights:</p><p>1 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<sup>−1</sup>).<br>2 A screen-printed graphene conductor exhibits a high electrical conductivity of 1.49 × 104 S m<sup>−1</sup> and good mechanical flexibility.<br>3 An electrochemical sodium ion sensor based on graphene ink exhibits an excellent potentiometric sensing performance in a mechanically bent state.<br>4 Real-time monitoring of sodium ion concentration in sweat is demonstrated.</p> ER -