The invention relates to a Sensor system (1) for detecting the presence or concentration of an analyte (A) in a medium (M), comprising: a sensor (10) having a sensor head (100) comprising a chamber (101), which sensor head (100) comprises a permeable area (105) through which the analyte (A) can pass into the chamber (101) when the sensor head (100) contacts said medium (M), a cross-linked hydrogel (H) filling said chamber (101), which hydrogel (H) is configured to undergo a change in volume when contacting the analyte (A) passed into the chamber (101) which leads to a change in pressure in said chamber, and a pressure sensor (102) configured to measure the pressure (P) in said chamber (101) for detecting the presence or concentration of said analyte (A).
