## 2 Impedance Spectroscopy
### Scopes of Application
#### 2.1.2 Is Applied in Forest and Agriculture Management
[79] developed a flexible electrode based on an MWCNTs nanocomposite functionalized with copper (Cu) and tungsten trioxide (WO\({}_{3}\)) nanoparticles for sensing the valuable life of lubricating oils. Intending to establish a quality control tool for oil samples, they applied EleIS to determine the electrical response of nanocomposites to oils' oxidation dynamics (obtained via the application of a four-points measuring setup in the frequency range of 1 Hz to 1 MHz), which showed it to be essential to differentiate fresh oil from aged ones. Due to the demands of the soft robotics area, [PERSON] et al. [80] used EleIS to characterize a tactile, flexible, and highly sensitive proximity sensor (for the measurements, they used a four-points configuration and a stimulus possessing a frequency of 100 kHz). The sensor prototype was produced using carbon micro-coils on a dielectric elastomer substrate. The researchers demonstrated that sensors with dimensions of 10 cm \(\times\) 10 cm could detect objects with a mass of the order of mg at up to 15 cm from the sensor surface, with repeatability and structural durability. [PERSON] et al. [81] proposed an electrically functional adhesive tape for detecting water leaks in plumbing systems. The tape was made using low-cost commercial materials, and presented a sandwich design consisting of a sheet of dielectric material between layers of flexible electrodes, followed by adhesive fixation layers. The entire length of the device inside the tubes was monitored by an electronic control unit using the EleIS technique (a conventional four-points measuring strategy was used, stimulated by a sinusoidal signal posing a frequency of 10 Hz and peak-to-peak voltage of 10 V). The build devices were successfully applied to monitor leaks of minimum volumes of water (on the order of \(\upmu\)L) with a temporal resolution of 5 s. The authors expect the positive results to serve as the basis for developing continuous-leak-monitoring systems in real-time and with a viable cost-benefit. [PERSON] et al. [82] developed a carbon dot-based electronic tongue to detect milk bacteria. Zein electrospun nanofibers (regenerated protein fibers made from corn and maize) were dispersed over a carbon layer to provide the nanodevice with a more reactive surface. EleIS monitored the population dynamics of _Staphylococcus aureus_ bacteria in milk (measures were conducted utilizing a four-points measuring setup for frequencies between 1 Hz and 2 MHz), providing a unique electrical behavior pattern when in contact with the device. The obtained capacitance data were translated into machine language and interpreted according to the known conditions of the infected milk samples. The results confirmed a device with high sensitivity, selectivity, and reproducibility, with an accuracy rate of around 80%. The authors predict that the scalability of the device could make it essential for the early and in situ detection of the disease without additional laboratory tests. IS Used on the Development/Optimization of Materials for Applications Related to Electrical Energy Production/Storage  
IS has been used to study new materials that comply with current electrical energy demands [83; 84; 85]. For example, photoelectrochemical cells are efficient devices for converting light into electrical energy and are an alternative solution to solid-state photovoltaic systems. Their construction is relatively simple and low-cost compared to other energy conversion technologies. Developing a photoelectrochemical cell involves the availability of conductive and semiconductor materials that close the electrical circuit when contacting the electrodes. A nanocomposite of erbium, zirconium, nickel sulphide, and graphene oxide was prepared on an ITO surface (glass sheet coated with indium-doped tin oxide) as a transparent photoelectrode for a photoelectrochemical cell [86].