Metal detectors can not only detect a variety of metals at various depths depending on the size of the object, but some can even detect the differences between various metals. This differentiation is done by measuring the deflection of the magnetic field generated by the metal detector. Titanium is often used in medical implants, so patients with implants that contain titanium often have to make this known to airport security personnel in order to pass inspection.

Currently, the development of TiO₂ memristors is associated with their use in modern highly technological applications, such as resistive random-access memory (RRAM), biohybrid systems, and sensors, as schematically shown in Figure 1A. In this mini-review, we briefly outline and summarize the key milestone achievements, as well as recent advances in the synthesis, fabrication, and application of TiO₂-based memristors. A special focus is placed on the relationships between the synthesis and deposition methods, the effects of post-synthesis treatment, and the resistive switching properties.

The raw material used in this method is FeSO4. In order to maintain the Fe3 + concentration in the reaction medium in a specific range, reducing agent iron sheet is added in the reaction process. Iron yellow crystal seed was added and air was introduced to synthesize iron yellow under certain pH conditions. The method mainly includes two steps: (1) firstly, FeSO4 · 7H2O is used as raw material, NaOH or NH3 · H2O is used as precipitant or pH regulator, and air is used as oxidant to prepare crystal seed; (2) Iron yellow is produced by two-step oxidation with crystal seed, FeSO4, iron sheet and air.