## 3 Results and Discussion
### Reuse
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Type** & **Capacity** & **Chemistry** & **Costs 1** [**5/unit**] & **Cycle Durability** \\ \hline \multirow{8}{*}{Non-rechargeable} & \multirow{8}{*}{40–50 mAh} & Alkaline Manganese Dioxide & & \\  & & Lithium & & \\ \cline{1-1}  & & Lithium Manganese Dioxide & & \\ \cline{1-1}  & & Lithium Poly-Carbon & & \\ \cline{1-1}  & & Monofluoride & & \\ \cline{1-1}  & & Silver Oxide & & \\ \cline{1-1}  & & Lithium Manganese & & \\ \cline{1-1}  & & Nickel Metal Hydride & 2.52–9.49 & 1200–2000 \\ \hline \hline \end{tabular} \({}^{1}\) United States prices.  
\end{table} 
Table 5: Comparison rechargeable/non-rechargeable coin-size batteries. actually widens the opportunities of usage. Indeed, the protocol states that the internal memory can be read or written, with two distinct commands: Write command, which stores a single 16-bit word, and BlockWrite command, which allows writing one or more 16-bit words per time. The standard also includes two levels or password, kill password and access password, that allows to lock or permanently lock write operations, or to enable or permanently enable such command with or without encryption. Consequently, this protocol allows reusing the tag since it can be rewritten without privacy or counterfeit problems, and since the write operation can be enabled and password protected. On the other hand, setting up a write password will have an impact on the tag production process, since the write operation can require more time when it is password protected. Therefore, production will be affected by higher production costs. In Figure 6, code differences between writing and write with lock operation are illustrated for the Bixon SLP-TX400 RFID tag label printer, showing that the secured writing operation requires two additional instructions. The second important feature for reuse of passive RFID tags is the durability. Most UHF passive tags are manufactured over plastic or paper self-adhesive labels. Thus, the process of removing the tag from an object could destroy the link between the RFID chip and the antenna, compromising the functionality of the tag itself. In other words, UHF passive tags cannot be easily reused, unless they are enclosed in protective plastic or other material that will allow them to survive the removal process. In Table 4, several UHF passive tags with different substrate materials and relative costs are reported. It is evident that the price of a simple, self-adhesive paper tag is lower, but the difference is not as significant, especially when some additional features are required for a normal cycle of operation, such as waterproof features for outdoor applications, which typically occur in the supply chain. Based on all the variables that have been identified for the reuse process of UHF passive RFID tags, it is possible to project a cost/benefit hypothetical analysis, with the following considerations:  
* The time needed for different tag writing operations may differ, depending on technology and data payload to be programmed. For this analysis, the example codes of Figure 7 have been considered, with five commands and seven commands for a simple write operation and secured writing operation, respectively, and assigning a uniform computational cost per each operation. * Prices associated with each type of passive tag may vary, depending on the producer and requested quantity. Best case, lower costs for standard, self-adhesive tags and pet flexible, transparent tags-as reported in Table 6--have been considered. * Not all the tag programmers are compatible with password read/write operations. However, the initial investment for a proper programmer has not been considered, since it is strongly dependent on many other factors that are linked to the needs of the company. Figure 6: The Bixon SLP-TX400 RFID code examples for writing and secured writing operations.