Self‐Powerbility in Electrical Stimulation Drug Delivery System

Abstract

DOI: 10.1002/admt.202100055 that increase safety, therapeutic effect and patient compliance are the key point. The development of materials, electronics, and micromechanical technology has promoted the extensive research and rapid development of DDS for time and spacespecific release. External stimulating signals, such as temperature,[1,2] magnetic,[3] electrical,[4–6] optical,[7] and ultrasound[8] and internal stimulating signals, such as glucose[9] and pH[10] can be used to trigger or control drug release and achieve the purpose of drug administration on demand. Among them, the electrical stimulation system has attracted much attention because electrical signals are easily controlled and can allow repeatable and reliable drug release for clinical needs. At the same time, it can be easily combined with sensors or microchips to control drug delivery and information feedback. It lays the foundation for remote diagnosis and treatment, as well as on-demand precision medicine.[11] Electrical stimulation DDS is to load the drug into the electric-responsive carrier and use the electric field or current in vitro or in vivo to promote or control drug release. Drug release can be simply divided into pulsed drug delivery and continuous constant speed drug delivery, the drug release can last several days or years. The main research of electrical stimulation DDS can be divided into three parts, including electroactive biomaterials, electrical supply system, and the route of administration. Electroactive biomaterials including conductive polymers, conductive hydrogels, etc. Which have been chemically modified and physically doped to obtain more materials with excellent performance and good electrical responsiveness for drug delivery. The route of administration ranges from transdermal administration to injectable, implantable, and ingestible DDS. In addition to wireless microchips, electrodes are usually placed on the skin or placed subcutaneously, and the electrical stimulation system works by placing them on the skin or by injection or implantation into the body. It is suitable for different needs and administration scenarios. Various commercial power sources are still the most commonly used sources for stimulation, but with the rise of mobile medical care, more attention has been paid to various self-powered medical devices. Selfpowered wearable and implanted generators based on triboelectric, piezoelectric, photovoltaic, hydrovoltaic, biofuel, galvanic, and pyroelectric have been extensively studied (Figure 1). In this review, we will briefly summarize the current electroactive biomaterials and recent advances in the development of drug delivery by electrical stimulation, the self-powered harvesters used in DDS at present will be highlighted. Finally, we will present the challenges and opportunities of electrical stimulation DDS. On-demand drug delivery is one of the main research directions of the drug delivery system (DDS). At present, with the development of various stimulus-responsive materials and technology, it is possible to regulate drug release through various external or internal stimuli. Among them, electrical stimulation DDS has great potential due to its easy combination with sensor or microchip and precise time and space controlled-release ability. At the same time, with the rapid growth of research in self-powered devices, the selfpowerbility of electrical stimulation DDS has also received a lot of attention. In this review, the current biomaterials used in electrical stimulation DDS, such as conducting polymers, electroconductive hydrogels, carbon-based nanomaterials, metal, and semiconductors are first introduced. Further the route of administration and recent advances of electrical stimulation DDS is summarized. The development and classification of self-powered devices used in DDS are highlighted. In the end, the major challenges and future perspectives of electric stimuli-responsive DDS are discussed.