It is well known that suction is one of the stress state variables that control the behavior of soils and some porous materials. This paper presents a sensor based on Micro electromechanical systems (MEMS) technology that allows the detection of changes in relative humidity (RH) within the soil. By using thermodynamic concepts, the RH can be converted to total suction. The sensor delivers a quick response time, no hysteresis and it is not affected by temperature. The MEMS sensor exhibited a much faster response to changes in relative humidity (total suction) when compared with the non-contact filter paper technique. The MEMS sensor was also used to measure high total suction in two clayey soils and proved to improve the SWCC fit.