A system comprising a disposable device and hand held reader can perform a variety of electrochemical measurements on blood or other fluids. In operation, a fluid sample is drawn into the disposable device through an orifice by capillary action. The orifice is sealed off and the disposable device is inserted into the reader. The reader which controls the test sequence and flow of fluid causes a calibrant pouch located inside the device to be pierced, releasing the calibrant fluid to flow across the sensor arrays to perform calibration. Next an air bladder located in the device is depressed, forcing the sample across the sensors where measurements are performed and read by the reader which performs the calibrations. Once the measurements are made, the device can be withdrawn from the reader and discarded.