Abstract: In described embodiment a method and an apparatus are provided for blood characterization. A closed loop electrical circuit employs as part of the circuit, a time varying resistive path that is made out of blood constituents and other chemicals. As the blood characteristics are changing, the resistance of the electrical path is also changing. The resistance change over a predefined time window is used to determine the blood thickness information. The resistance value change over another predefined time window is used to determine the blood density information. Presence as well as absence of blood constituents is determined from the resistance change over a pre-defined time window.