||The reactions of vanadium redox flow batteries (VRFBs) are quite complex and the internal environment is strongly acidic. The internal voltage, current, temperature and flow distribution play a very important role in the performance of a VRFB. The VRFB, which was developed by our R&D team, encountered easy leakage of electrolytes during assembly. Additionally, the strongly acidic environment can easily cause aging or failure of these VRFBs and of the micro-sensor. Therefore, this research was aimed at the need for real-time micro-diagnosis inside the VRFB. The use of micro-electro-mechanical systems (MEMS) technology was proposed so as to develop a flexible, integrated (current, voltage, flow and temperature), micro-sensor, and a durability test was conducted after packaging. Further, we performed real-time monitoring of the VRFBs. The main finding was that the encapsulation contributed to the stability of the micro-sensor without any failure due to excessive flow impacting the sensor. In the end we successfully used a 3D printed package to protect the micro-sensor.