Memristors: The fourth circuit element
Brad Gates

Abstract:
 Traditionally, there have been three different basic components to circuits, namely capacitors, resistors, and inducers.  However, a new basic element to a circuit has been developed.  This element is known as the memristor.  A memristor is essentially a resistor with memory. The resistance of a memristor is dependent upon the amount of voltage which has been applied to it and the length of time this voltage was applied.  The concept of a memristor was first developed in 1971. However, it was not until recently that researchers at HP Labs were able to build the first working one.  This is due mostly to the size dependence of the memristor.  The changes in resistance of a memristor are not detectable until the memristor is in the nanometer range. When the thickness of the memristor is larger than this, it is indistinguishable from a standard resistor. The main advantage of the memristor in modern computing is that it retains its resistance even when no voltage is applied.  Unlike the components which are currently used for running memory in computers, information contained within memristors does not degrade when the power is removed.  This would allow a computer to retain its saved state while off and would require less power to run when it is on. Another advantage to memristors is their analog nature.  Whereas the switches in computers have only two states, on and off, the resistance in a memristor does not have a set amount of values it can be.  While the memristor can still be used for digital memory storage, there is research currently into the development of analog computers using memristors.  These analog computers would theoretically have a much simpler time with many processes which are at best poorly done with current computers, such as face recognition.  Although the manufacturing of memristors can be done using equipment common in circuit production, no circuit designs yet exist to take advantage of memristors.  Until such circuits exist, memristors will not be able to be used.