In the IoT, a small amount of payment (i.e., micropayment) enables the trading of sensor data collected by IoT devices. The IOTA cryptocurrency, which achieves high-speed transactions without transaction fees, shows the potential to realize such micropayment. In this work, we introduce and implement an IOTA-based micropayment system for IoT devices (i.e., Raspberry Pi), assuming an air quality monitoring application. We then evaluate the latency performance and power consumption.