Design of a Data Logger for Biomedical Signals

Recording of physiological and psychological variables in real-life condition is useful in treatment of patients with health problem. In developing countries, delays in giving medical assistance to individuals (patients) usually occur due to the cumbersome process of getting patients’ information to medical personnel. Due to advancement of low cost and portable electronic devices, this paper presents a non-invasive device that acquires and stores electrocardiogram (ECG) and temperature signals of patients. The analog signals from the signal conditioning circuit are sent to the microcontroller’s analog to digital converter. The data is then logged in a SanDisk (SD) card for later transfer to a personal computer (PC). Playback of analog signals is also included using the microcontroller’s CCP module to convert the stored data back to analog. A visual basic Graphical User Interface (GUI) is designed to view the graph of the data on PC. The circuit requires no external component for ADC and a simple low pass filter for DAC, resulting in reduced size of overall circuit and cost of