Electrosensing antibody probing system (e- Ab sensor), which was developed for the rapid and sensitive detection of hapten, proteins or viral antigen in medical samples, will be used for analyzing the interaction kinetics between Q.anti-EV71 and its antigen EV71 present in EV71 patients and normal sample. The system incorporates the use of engineered semiconductive antibodies or virus in vertical and lateral chip (eVchip) or lateral flow through (eVsignal) formats. In electrosensing virus probing, semiconductive antibodies are bound as a suitable electrosensing probe which specifically and selectively binds EV71 epitope target molecules in the test serum. In comparison with results from direct sequencing of EV71, the investigators evaluate the performance of e- Ab sensor, including reproducibility, sensitivity, specificity, and cross-reaction. The potential factors which may interfere with the results would be investigated. e- Ab sensor threshold decisions must maximize its sensitivity. Therefore, the threshold value in the test group is to find the decision could have 90% sensitivity and 90% specificity. With such technique, the investigators hope to make early diagnosis and give EV71 patients early treatment to reduce the complications and case-fatality rate.