Sepsis is a clinical syndrome with complex interactions between microorganism, host immune, inflammatory and coagulation response. The mortality rate associated with septic shock is high, up to 40-70%. Currently, the diagnosis of sepsis depends on microbial infection and systemic inflammatory response syndrome, which lacks sensitivity and specificity. Accordingly, Society of Critical Care Medicine (SCCM) offered new recommendations about the diagnosis of sepsis in 2001, which included the serum level of procalcitonin (PCT). Increased PCT levels through the clinical course correlated with higher mortality in critically-ill patients. On the other hand, recent studies also showed PCT levels could guide the antibiotic treatment in patients with sepsis or lower respiratory tract infection. Besides usage in sepsis population, serum PCT level could also be used for aids in diagnosis of bacterial infection and for guide of antibiotic treatment in acute exacerbation of chronic obstructive airway disease. However, current method of PCT assay depends on the Kryptor system developed by BRAHMS, Germany, with the functional sensitivity of 60 pg/mL. Each assay costs 1300 NT dollars, which is too expensive for serial follow-up of serum PCT levels. A real-time diagnostic technique with e- Ab sensor for serum PCT level measurement will offer a test with lower cost, and increase the applicability of serum PCT level in daily clinical practice. Here, the investigators conduct a study to develop a real-time diagnostic technique with e- Ab sensor for serum PCT level measurement in patients with sepsis.