## 4 Experimental Data
\begin{table}
\begin{tabular}{l c} \hline \hline  & ELECTRICAL \\ \hline Supply voltage & 1.5-3.6 V \\ Max current & 0.4 mA continuous when reading on-chip sensors with EIS \\ Size & 12 \(\times\) 15 mm, 3 mm thickness \\ Interface & 12C or SENSIBUS, single data wire multidrop sensor array \\  & cable interface, 1.5-3.6 V \\ Unique identifier & OTP 48 bits unique device identifier, 16 bits user-defined \\ \hline \multicolumn{3}{c}{ELECTRICAL IMPEDANCE SPECTROSCOPY} \\ \hline Frequency & From 3.1 mHz to 1.2 MHz \\ Vpp output sinewave & From 156 mV to 2.8 Vpp \\ Coherent demodulation & 1 st, 2 nd, or 3 rd harmonic \\ Output & Reciprocal of real or imagery component \\ Wide measurement range & From ohms to 100 M\(\Omega\) \\ \hline \multicolumn{3}{c}{TEMPERATURE} \\ \hline Range & \(-\)40-125 \({}^{\circ}\)C \\ Accuracy & \(\pm\)0.1 \({}^{\circ}\)C \\ Thermodynamics & Calorimetry, enthalpy, and exothermic or endothermic \\ \hline \multicolumn{3}{c}{ELECTROCHMICAL METHODS} \\ \hline pH & From 3 to 14, potential of platinum vs. clads-platinum \\ ORP & Total oxidation and reduction potentials \\ RedOx & Reduction or oxidation activity (free chlorine, hardness) \\ Voltammetry & Specific reduction or oxidation potentials \\ Anodic stripping voltammetry & Measures heavy metals \\ Electro-catalysis & Noble metal IDEs measure current specifically \\ \hline \multicolumn{3}{c}{IMPEDANCE METHODS} \\ \hline Conductivity spectroscopy & Resistivity, salinity, EC, TDS, and absorption dynamics \\ Dielectric spectroscopy & Turbidity, SS, biomass total and active, and hydrocarbon \\ \hline \end{tabular}
\end{table} 
Table 2: Technical specifications of SCW used for our smart monitoring test. Figure 2: An experimental ASV equipped with an innovative probe under development in our laboratory. An SCW is located on board an ASV, and the CPU directs the movements of the instrument over a network of fixed points to transmit data sets and, eventually, alarms according to thresholds set by local administrators. The probe is automatically extracted from the marine water at given time intervals and mapped to avoid corrosion of the metal plates. As mentioned above, an SCW needs to be trained to recognize pollutants and other substances of ecological interest. For this purpose, various amounts of key compounds (such as nitrogen and phosphorus compounds) were tested and used to calibrate the probe. Our results indicate that low amounts of important pollutants were detected by the instrument, but a full set of permutated measurements is needed to train the instrument to recognize compounds in any pattern of reciprocal concentrations. Another constraint is represented by the oxidizing power of the seawater, because continuous immersion in water rich in NaCl produces fast deterioration of some of the metal plates, drastically reducing the performance, as demonstrated by our tests. For this reason, the SCW was mounted over the ASV by means of an immersion device able to move the SCW up and down at various time intervals, protecting it with frequent washes in distilled water followed by mopping and drying of its surface. However, this SCW-equipped ASV was demonstrated to be quite promising for coastal monitoring, because its performance may improve through auto-training and also because of the easy installation over small smart vehicles wirelessly connected to the control stations on land.