*Biometrics*

The second main discipline has been the use of biosensors for strictly biometric purposes. Namely, current research has aimed to use bioassays for the identification and di fferentiation of individuals. As mentioned previously, the content of di fferent metabolites in sweat can be quantified, which can be used to find di fferences between people. This has implications in both the prior forensics section, biometrics in general, and even cybersecurity, which will be explained below. This method can be used to provide an alternate to DNA testing similar to the other techniques being developed for forensics. This kind of technology is similar to emerging research in biosensors and bioelectronics [78,79]. As mentioned previously, the content within a person's sweat is a result of metabolic processes [24–27,59,80] related to what can be a person's identifying factors such as age, biological sex, diet, and activity level. By taking measurements of and comparing results for multiple biomarkers, one can di fferentiate a person from others with these fluctuating factors. This can be applied for the unlocking of smart devices as the technology is moving in this direction as well [81–83].

As mentioned previously, sweat has been an emerging source of information in both forensics and biometrics. Many studies have been done for the advancement of various methodologies for di fferent compounds found in sweat [84–88]. Further descriptions of some of the recent methodologies that have been developed for sweat analysis can be seen in Table 1 below.


**Table 1.** Recent biosensor analysis techniques for sweat.


**Table 1.** *Cont*.
