Unencapsulated silicon based resistors are potential bio-sensors. These resistors which are fabricated in large numbers on silicon are diced to form individual resistor. The effective resistance of this resistor is reduced when a resistive bio element is deposited on it, hence forms the basis for a sensor. By simple comparison, the characteristics of the source of bio-element are determined. Further, only a transduction circuit, a comparator and display are needed to form a simple bio-based instrument. Potential advantages of this sensor are low cost, simple and robust.