A novel low-cost ubiquitous sensor system was built on a microminiaturized electrochemical chip positioned on a gold electrode using a low-frequency wireless communication chipset to detect pesticides in situ. Different residual organophosphorus pesticides can be detected based on an enzyme reaction with electron transfer in the portable sensor system using a sensor array chip. This disposable, low-cost, and microminiaturized biosensor chip can be used to detect harmful residual agrichemicals within 3-4 min on a solid surface.