Background: Acute myocardial infarction (AMI), usually caused by atherosclerosis of coronary artery, is the most severe manifestation of coronary artery disease which results in a large amount of death annually. A new diagnosis approach with high accuracy, reliability and low measuring-time-consuming is essential for AMI quick diagnosis. 
Purpose: The objective of this study was to develop a new point-of-care testing system with high accuracy and reliability for AMI quick diagnosis.
Patients and methods: 50 plasma samples of acute myocardial infarction patients were analyzed by developed Smartphone-Assisted Pressure-Measuring-Based Diagnosis System (SPDS). The concentration of substrate was firstly optimized. The effect of antibody labeling and matrix solution on measuring result were then evaluated. And standard curves for cTnI, CK-MB and Myo were built for clinical sample analysis. The measuring results of 50 clinical samples were finally evaluated by comparing with the measuring result obtained by CLIA. 
Results: The concentration of substrate H₂O₂ was firstly optimized as 30% to increase measuring signal. A commercial serum matrix was chosen as the matrix solution to dilute biomarkers for standard curve building to minimize matrix effect on the accuracy of clinical plasma sample measuring. The standard curves for cTnI, CK-MB and Myo were built, with measuring dynamic range of 0–25 ng/mL, 0–33 ng/mL and 0–250 ng/mL, and limit of detection of 0.014 ng/mL, 0.16 ng/mL and 0.85 ng/mL respectively. The measuring results obtained by the developed system of 50 clinical plasma samples for three biomarkers matched well with the results obtained by chemiluminescent immunoassay.
Conclusion: Due to its small device size, high sensitivity and accuracy, SPDS showed a bright potential for point-of-care testing (POCT) applications.
Keywords: acute myocardial infarction, diagnosis, pressure sensor, smartphone, Pt nanoparticle