A transducer device for detecting an environmental state within a biological material including a channel comprising a fluid, a hydrogel material, which is adapted to change its volume when getting into contact with an environmental material and/or when detecting an environmental change, and which is mechanically coupled to the channel such that the volume of the channel changes when the volume of the hydrogel material changes. The transducer device further includes a sensor, which is adapted to generate a signal upon detection of the change of a physical property of the fluid that is induced by the volume change of the channel. By applying the transducer device, an accurate monitoring of physiological parameters, for which the hydrogel material is sensitive is possible. It is also possible to apply the transducer device outside of the bodily lumen, for example to monitor the blood of a patient outside the bodily lumen.