Breath analysis based on SERS sensors can distinguish differentstages of gastric cancer, with a SERS sensor analyzing volatileorganic compound (VOC)159,160 biomarkers in exhaled breath. Aclean SRES sensor decorated with Au NPs and rGO was originallydesigned by Cui et al.,161 which has successfully identified 14 VOCbiomarkers in exhaled gas, as shown in Fig. 10A. This strategy hasbeen successfully used for distinguishing a mass of simulatedbreath samples and patient breath samples with a high selectivity(483%) and good specificity (492%), respectively, which providesenormous potential for clinical translation in the coming future.Likewise, salivary analysis based on SERS sensors designedby Cui et al. exhibits a similar performance for the identificationof early and advanced gastric cancer patients.162 Biomarkers insaliva provide feasibility to obtain SERS fingerprint bands asintroduced before. Fig. 10B shows a combination of SERSspectra of various biomarkers in saliva from advanced cancerpatients, early cancer patients, the control and a blank sensor.Three distinguishable clusters can be defined to signify differentpersons in different stages of cancers via Principal CompoundAnalysis, as estimated in Fig. 10C. This method has more than87.7% specificity and 80% sensitivity for the distinction ofboth simulated and clinical saliva samples, and also providesa direction of advance and prospects for clinical applications.