A closed‐loop system that can mini‐invasively track blood glucose and intelligently treat diabetes is in great demand for modern medicine, yet it remains challenging to realize. Microneedles technologies have recently emerged as powerful tools for transdermal applications with inherent painlessness and biosafety. In this work, for the first time to the authors' knowledge, a fully integrated wearable closed‐loop system (IWCS) based on mini‐invasive microneedle platform is developed for in situ diabetic sensing and treatment. The IWCS consists of three connected modules: 1) a mesoporous microneedle‐reverse iontophoretic glucose sensor; 2) a flexible printed circuit board as integrated and control; and 3) a microneedle‐iontophoretic insulin delivery component. As the key component, mesoporous microneedles enable the painless penetration of stratum corneum, implementing subcutaneous substance exchange. The coupling with iontophoresis significantly enhances glucose extraction and insulin delivery and enables electrical control. This IWCS is demonstrated to accurately monitor glucose fluctuations, and responsively deliver insulin to regulate hyperglycemia in diabetic rat model. The painless microneedles and wearable design endows this IWCS as a highly promising platform to improve the therapies of diabetic patients.

Microneedle arrays (MA) have been extensively investigated in recent decades for transdermal drug delivery due to their pain-free delivery, minimal skin trauma, and reduced risk of infection. However, porous MA received relatively less attention due to their complex fabrication process and ease of fracturing. Here, we present a titanium porous microneedle array (TPMA) fabricated by modified metal injection molding (MIM) technology. The sintering process is simple and suitable for mass production. TPMA was sintered at a sintering temperature of 1250°C for 2 h. The porosity of TPMA was approximately 30.1% and its average pore diameter was about 1.3 μm. The elements distributed on the surface of TPMA were only Ti and O, which may guarantee the biocompatibility of TPMA. TPMA could easily penetrate the skin of a human forearm without fracture. TPMA could diffuse dry Rhodamine B stored in micropores into rabbit skin. The cumulative permeated flux of calcein across TPMA with punctured skin was 27 times greater than that across intact skin. Thus, TPMA can continually and efficiently deliver a liquid drug through open micropores in skin.

Four-dimensional (4D) printed magnetoactive soft material (MASM) with a three-dimensional (3D) patterned magnetization profile possesses programmable shape transformation and controllable locomotion ability, showing promising applications in actuators and soft robotics. However, typical 4D printing strategies for MASM always introduced a printing magnetic field to orient the magneto-sensitive particles in polymers. Such strategies not only increase the cooperative control complexity of a 3D printer but may also induce local agglomeration of magneto-sensitive particles, which disturbs the magnetization of the already-printed structure. Herein, we proposed a novel 4D printing strategy that coupled the traditional 3D injection printing with the origami-based magnetization technique for easy fabrication of MASM objects with a 3D patterned magnetization profile. The 3D injection printing that can rapidly create complex 3D structures and the origami-based magnetization technique that can generate the spatial magnetization profile are combined for fabrication of 3D MASM objects to yield programmable transformation and controllable locomotion. A physics-based finite element model was also developed for the design guidance of origami-based magnetization and magnetic actuation transformation of MASM. We further demonstrated the diverse functions derived from the complex shape deformation of MASM-based robots, including a bionic human hand that played “rock-paper-scissors” game, a bionic butterfly that swung the wings on the flower, and a bionic turtle that crawled on the land and swam in the water.

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