Abstract: Objective To design a wireless low-energy nocturnal erectile signal sensor which can replace the wired transmission sensor and reduce the size of the wearable device, aming to improve the wearable experience of clinical users. Methods The consistency of wearing comfort and monitoring initial value was improved by setting the sensor wearing identifier and wearing detection program. A multi-functional sensor was composed of a flexible tension sensor and a flexible pressure sensor to collect the data of penis change. A bluetooth module was used to transmit the data to the personal computer （PC）, then quintic polynomial curve fitting was performed by the method of least squares using the software on the host PC, and finally according to the capacitance-time and pressure-time relationships, a nocturnal erection curve was obtained. Results Through the simulation experiment, the sensor signal was successfully transmitted to the PC, and the software displayed the change of pressure and circumference in real time. Conclusion This study has realized erectile monitoring wirelessly, and separated the information acquisition module and the information processing module, which further facilitates the application of nocturnal penile tumescence test （NPT） technology in perioperative surgery.

Key words: Pressure sensing module, Capacitance sensing module, Wireless transmission technology, Least square methods, Curve fitting