The evolution of wearable smart devices coupled with advanced sensor technology has rejuvenated research in mobile healthcare. Despite the growing interest in the measurement of bio-signals, no studies have focused on mobile penile tumescence. Measuring penile tumescence daily is important not only for patients suffering from erectile dysfunction but also because it serves as a dependable barometer of men's health. Rigiscan has been the most reliable and widely used device employed to measure nocturnal penile tumescence, but it is heavy, bulky and has several limitations to being a wearable device. This paper introduces an innovative mobile penile tumescence measuring system connectable to any smartphone through wireless communication. It comprises of a progressive sensor that allows seamless everyday usage due to its small size, light weight and low power requirements. The sensor consists of inexpensive materials, so it can be replaced daily for hygiene reasons. We tested proposed system with 10 subjects in over 30 sessions for a total of more than 100 hours. To check the validity of PT-scan and its compatibility with Rigiscan, the two systems' measurement results were compared and a high correlation coefficient of 0.96 (P < 0.001) was obtained.