A device based in microsystem technology for extracting and storing fluid samples is presented in this paper. The solution presented in this paper is a controlled low-cost extractor. The main advantage of this device against other solutions used so far, is the control over the activation of the extraction. Its main features are a very simple structure and easy method of activation. The structure is so useful that can be used to obtain an injector too. Another advantage is its manufacture in plastic, which simplifies its fabrication and decreases the cost. A reactive can be located in it to sense the chemical substances concentration of the absorbed fluid. In this case, two electrodes are included in the design.