Emerging microelectronic microneedles (eMN) for biomedical applications

Microneedles, an emerging medical tool, have attracted significant attention for their superior ability to puncture the skin noninvasively and painlessly, facilitating tasks such as physiological monitoring, disease diagnosis, and transdermal drug delivery. However, if microneedles are used alone, the efficiency of drug delivery or physiological substance extraction is still not very efficient. In recent years, the rapid development of microelectronic microneedle (eMN) devices, integrating microneedle technology with microelectronics, has solidified the foundation of MN-based percutaneous disease diagnosis and treatment platforms. However, comprehensive review reports on this topic remain scarce. This paper systematically reviews the research progress in the manufacture, processing and biomedical applications of eMN devices. Initially, we present an overview of the materials used in eMNs, including MN-fabrication materials and substrate materials that enhance electrical conductivity. Subsequently, we delve into the various eMN preparation techniques, including micromolding, etching, laser cutting, and 3D printing, along with suitable power sources such as batteries adaptable to diverse materials. Additionally, we elaborate on the mechanism of action of these eMN devices, including ionophoresis, electroporation, thermal stimulation, and ultrasound. Finally, we summarize the application progress of some typical eMN devices in drug delivery and physiological monitoring. By perusing this article, readers can gain valuable insights into the design of eMN medical devices, thereby catalyzing the advancement of intelligent and personalized medicine.