Microneedle (MN) is a key technology of the biomedical engineering field due to its capability of accessing the biological information in a minimally invasive manner. One of the huge demands for next-generation healthcare monitoring is continuous monitoring, especially of blood glucose concentration. For this, MN should be kept inserted into the human skin for a certain period of time, enduring stresses induced by daily human motion and at the same time measuring biomarkers in ISF. However, conventional MNs for biosensing are not suitable for a long term insertion due to the rigid structure and biological risks of MN breakage. In this study, a novel MN structure is proposed and investigated by combining flexible “sponge-like” porous PDMS matrix and coating by biodissolving hyaluronic acid (HA). The fabricated porous MNs coated with HA show ideal mechanical characteristics, by which the MNs are rigid enough to penetrate the skin and become flexible after insertion into the skin. It is also shown that the MN array successfully extracts ISF in vitro and in vivo not by capillary action but by repeated compressions. The results show the applicability of the flexible MNs to continuous blood glucose monitoring.

微针（MN）是生物医学工程领域的一项关键技术，因为它能够以微创的方式获取生物信息。对下一代医疗保健监测的巨大需求之一是持续监测，尤其是血糖浓度。为此，MN 应保持插入人体皮肤一段时间，承受由日常人体运动引起的压力，同时测量 ISF 中的生物标志物。然而，由于 MN 断裂的刚性结构和生物风险，用于生物传感的传统 MN 不适合长期插入。在这项研究中，通过将柔性“海绵状”多孔 PDMS 基质和生物溶解透明质酸 (HA) 涂层相结合，提出并研究了一种新的 MN 结构。涂有 HA 的制造多孔 MNs 显示出理想的机械特性，由此 MNs 具有足够的刚性以穿透皮肤并在插入皮肤后变得柔韧。还表明MN阵列成功提取了ISF在体外和体内不是通过毛细作用而是通过反复压缩。结果显示了灵活的 MN 对连续血糖监测的适用性。