A fluid flow sensing and bubble detecting apparatus includes a housing comprising a channel configured to receive a tube through which fluid flows; a sensor apparatus disposed within the housing, which includes a first sensor operable to measure flow rate of fluid and to detect bubbles in flowing fluid; and a temperature sensor operable to detect temperature of the flowing fluid; and a processor connected to receive fluid flow rate data obtained by the first sensor, to receive bubble detection data obtained by the first sensor, and to receive fluid temperature data obtained by the temperature sensor, wherein when a tube through which fluid flows is disposed in the channel of the housing, the first sensor measures the flow rate of the flowing fluid and detects bubbles therein, and the temperature sensor measures the temperature of the flowing fluid, and the processor calculates in a short period of time a fluid flow rate corrected for temperature. All sensors are non-invasive and have no direct contact to the fluid in the tube, which might be blood. In accordance with additional embodiments, the fluid flow rate is additionally corrected for hemoglobin or hematocrit, and the effect of oxygen saturation on the hemoglobin or hematocrit data.