New methods for the monitoring of nocturnal erections.

The golden standard for measuring nocturnal erections is the RigiScan Plus. It is a relatively big and uncomfortable device dating from the previous century. The aim of this perspective is to conceptualize a user-friendly sensor that can be used at home for monitoring nocturnal erections. A literary search is carried out to explore the physiological changes during nocturnal tumescence and detumescence that can be measured non-invasively. Five sensor concepts are considered: plethysmography for penile arterial pulse, displacement sensor for axial length, strain gauges for radial rigidity and circumference, temperature sensors for measuring skin and cavernosal temperature, and a saturation sensor to measure hypoxia in cavernosal tissue during maximal rigidity. We think that due to practical issues, measuring penile length during sleep is impossible. Further research is recommended to investigate the remaining sensor concepts. Whether a combination of these techniques is favorable or only one of them should be studied more thoroughly.