## 2 Applications of Biosensors in Bacteria Detection
### Recognition of Bacteria Using Biosensors
#### 2.1.3 Electrochemical Biosensors
\begin{table}
\begin{tabular}{c c c c c} \hline
**Biosensor Type** & **Detected Bacteria** & **Limit of Detection** & **Assay Time** & **Ref.** \\ \hline SPR (with nonspecific adsorption of antibody) & _E. coli_ & \(4.8\times 10^{5}\) CFU/mL & No data & [PERSON] et al. (2018) \\ \hline SPR (with specific adsorption via & & & & \\ \(\text{avidin-biotin interaction}\) & _E. coli_ & \(6.2\times 10^{3}\) CFU/mL & No data & [PERSON] et al. (2018) \\ \hline SPR (with SAM formation & _E. coli_ & \(35\) CFU/mL & No data & [PERSON] et al. (2018) \\ \hline SPR (with gold coated magnetic & & & & \\ \(\text{nanoparticles}\) * & _E. coli_ & \(3\) CFU/mL & \(<\)70 min & [PERSON] et al. (2018) \\ \hline SPR (with one- and two step & & & \(4.7\times 10^{5}\) CFU/mL (one-step & \\ \(\text{sandwich assay}\)) & _S. typhimurium_ & sandwich assay) & No data & [PERSON] et al. (2018) \\ \hline SPR (full-length Det7 & & & & \\ bacteriophage tail protein (Det7)) & _S. typhimurium_ & \(5\times 10^{4}\)–\(5\times 10^{7}\) CFU/mL & \(\sim\)20 min & [PERSON] et al. (2016) \\ \hline BaTiO3-graphene-affinity & _Pseudomonas_ & No data & No data & [PERSON] et al. (2018) \\ layer-based SPR & _L. monocytogenes_ and _L._ & \(2\times 10^{2}\) CFU/mL & \(7\) h & [PERSON] et al. (2017) \\ \hline Localized surface plasmon & _V. cholerae O1_ & \(10\) CFU/mL & \(1\) h & [PERSON] et al. (2018) \\ resonance (LSPR) & _E. coli O157:H7_ & \(10\) CFU/mL & \(2\) h & [PERSON] et al. (2019) \\ \hline Fiber-optic SPR & _E. coli O157:H7_ & \(5\times 10^{2}\) CFU/mL & No data & [PERSON] et al. (2018) \\ \hline Fiber-optic LSPR & _S. typhimurium_ & \(128\) CFU/mL & \(100\) min & [PERSON] et al. (2018) \\ \hline SPR & _E. coli, Salmonella_ spp. & \(17\)–\(57\) CFU/mL for _E. coli_ and \(7.4\times 10^{3}\)–\(11.7\times 10^{3}\) CFU/mL for _Salmonella_ spp. & \(<\)80 min & [PERSON] et al. (2018) \\ \hline SPR & _E. faecalis_ & \(3.4\times 10^{4}\) CFU/mL & No data & [PERSON] et al. (2018) \\ \hline SPR & _M. tuberculosis_ & \(10^{4}\) CFU/mL & \(15\) min & [PERSON] et al. (2018) \\ \hline SPR & _Pseudomonas_ and & \(\text{no data}\) & No data & [PERSON] et al. (2018) \\ \hline SPR & _Pseudomonas_-like bacteria & no data & No data & [PERSON] et al. (2018) \\ \hline SPR & _E. coli_ & \(3.0\times 10^{2}\) CFU/mL & No data & [PERSON] et al. (2018) \\ \hline SPR & _M. tuberculosis_ & \(63\) pg/mL & \(2\)–\(4\) h & [PERSON] et al. (2018) \\ \hline SPR & _V. cholerae_ & \(50\) CFU/mL & \(60\) min & [PERSON] et al. (2018) \\ \hline SPR & _E.coli O157:H7, S. enteritidis, and L. monocytogenes_ & \(14\), \(6\), and \(28\) CFU/\(25\) g (mL) & No data & [PERSON] et al. (2018) \\ \hline SPR & _E. coli K-12_ & \(2\times 10^{4}\) CFU/mL & \(20\) min & [PERSON] et al. (2018) \\ \hline \end{tabular}
\end{table} 
Table 1: Summary of the whole bacteria detecting biosensors. In case of SPR and QCM, the different sensing strategies result in various limit of detection values (LOD). Thus, according to these results, the sensitivity of the biosensors can be improved by some development, for example applying nanoparticles. In general, the assay time is less than \(1\) h. (* represents label-based biosensors for direct comparison with label-free techniques).