MXene Nanosheet-Based Microneedles for Monitoring Muscle Contraction and Electrostimulation Treatment

MXenes belong to a large family of two-dimensional layered transition-metal carbides and nitrides. MXene nanosheets integrate the fascinating advantages of high electronic conductivity, excellent biocompatibility, and acid/base resistance. Herein, we demonstrate a "hospital-on-a-chip" system with multifunctional microneedle electrodes for biosensing and electrostimulation using highly stable MXene nanosheets. This system consists of integrated microchip biosensors for an efficient diagnosis and medical treatment elements for therapies, thus resembling a miniaturized hospital. Microneedles are composed of dozens of micron-sized needles that can be used as an effective and painless transdermal patch to puncture the dead skin barrier for drug delivery or biosensing purposes since they are directly in contact with the dermal layer inside the human body. The wearable MXene nanosheet-based microneedles can sense the tiny electric potential difference generated from the human eye movements or muscle contraction from the human arm. Therefore, the diseases associated with neuromuscular abnormalities such as myasthenia gravis can be monitored. Consequently, the transcutaneous electrical nerve stimulation treatment can be applied according to the feedback of the micro-biosensors. In addition, MXene microneedles can offer an electrically controlled drug delivery platform and the function of enhancing blood coagulation. Finally, MXene nanosheet-based microneedles provide an interesting platform for wearable micro-biosensors and offer an essential part of the hospital-on-a-chip system.