**5.1 Memristor**

*Bio-Inspired Technology*

**Figure 11.**

**Figure 12.**

*Dynamic delayed feedback loop.*

*Illustration of short-term dynamic memory.*

**20**

**Figure 13.**

**4.3 Dynamic behavior**

In general, the phase portrait is used to visualize how solutions of a delay system would behave. In this experiment, measured phase portraits are plotted through two signals from the feedback loop where one of them is recorded with the time

*Measured phase portrait of dynamic system in (a) T = 0.64 μs; (b) T = 1 μs; (c) T = 1.2 μs; (d) T = 1.4 μs.*

In neural network designs, the electronic circuit model of synapses can be implemented by an emerging non-volatile device, namely the memristor, which is a class of the resistive random-access memory (RRAM). In general, the memristor device is constructed in a metal-insulator-metal (MIM) structure, as illustrated in **Figure 14a**. The resistance of a memristor device can be gradually changed between its low resistance state and high resistance state as the voltage across the memristor device changes.

Memristors are typically fabricated in a 2D crossbar structure [54], which can be further extended to 3D space, as illustrated in **Figure 14c** and **d**, respectively.
