The QCM biosensor with AT-cut quartz has been used for the detection of various disease biomarkers found in human serum, namely the carcinoembryonic antigen (CEA); prostate-specific antigen (PSA); CD63 positive exosomes; tuberculosis biomarker; Dengue fever biomarker (non-structural protein-1 (NS1)); pancreatic disease biomarker (trypsin); hepatitis B core antigen (HBcAg); protein biomarker for malaria (PfHRP-2); and human immunodeficiency virus (HIV) biomarker (HIV-1 glycoprotein 41 (gp41), HIV-1 p24 antigen) [75,97,98,111,112,120,121,122,123,124,125,126,127,128]. The gene discussed is KLK3; the disease is tuberculosis.