A thin planar biological sensor is provided, comprising at least one flexible electrode used for contacting a subjects skin and measuring biological signal. The flexible electrode is made of silicon-silver-based material, in which a ratio of silicon to silver-compound is about 7:3. A conductive plate is coupled to the flexible electrode. A buffer layer covers the conductive plate and the flexible electrode. A printed circuit board is used to receive the measured biological signal. By employing the novel proposed biological sensor, it is advantageous of measuring biological signals not only EEG signals but also ECG and EMG signals. Besides being thin, planar, flexible and non-allergy attributing a low cost to the proper fabrications makes the proposed sensor characterized with a potential for becoming an important tool of medical measurement.
