We developed a sensor for detecting A2L/A3 refrigerant gas at different concentration levels. The sensor uses Quartz Crystal Microbalance (QCM)/Surface Acoustic Wave (SAW) technologies and Metal Organic Framework materials (MOF). The QCM/SAW sensor is coated with MOF materials which adsorb/desorb the target gas. The adsorption amount of the target gas induces a change in the parameters of the acoustic/vibration signal (resonance frequency, phase, dissipation) of the sensor. The parameter change is directly correlated to the actual concentration of the target gas present in the vicinity of the QCM sensor. This sensing technology enables fast responses for refrigerant leak detection. An initial screening of multiple MOF metarials is conducted. A hydrophobic MOF material which responds optimally to environmental conditions is obtained and is used in the sensing element. We designed the electrical circuit to capture the sensor's signal changes when exposed to A2L/A3 gas. Multiple testings are performed to gauge the sensor's stability and reatability over time. Using the integrated sensor, we can detect different concentrations of the A2L/A3 gas such as R-32.