The continuous monitoring of human health can greatly benefit from devices that can be worn comfortably or seamlessly integrated in household objects, constituting “health-centered” domotics. One of the key aspects for these devices to be successful is to be invisibly integrated and disappear in the background of our lives. Our group works on thin film devices made with plastic materials that can be used for electrochemically sensing of common analytes from easily accessible bodily fluids (e.g. sweat, saliva, urine). I will describe electrochemical transistors that detect ionic species either directly present in body fluids or resulting from a selective enzymatic reaction (e.g. ammonia from creatinine) at physiological levels. One important advantage of transistors compared to standard electrodes is their ability to amplify signals, thereby potentially giving rise to high sensitivity detection. Importantly, I will show that non-charged molecules can be detected by making use of custom-processed polymer membranes that act as “synthetic enzymes”. Using these membranes in conjunction with electrochemical transistors we demonstrate that we are able to measure physiological levels of cortisol in real human sweat. Because they are ultra-thin and they can be easily fabricated on soft, flexible substrates, polymer electrochemical transistors are promising candidates for wearables and domotics for continuous monitoring of human health.