Secrecy Sensor

The Secrecy Sensor is a dark detector described as "an object that looked something like an extra-squiggly, golden television aerial." It vibrates when it detects concealment and lies. In Another Way to Die, Wu Ying Ying mentions that it is "no use here, of course, too much interference — students in every direction lying about why they haven’t done their homework." However, it may have been responding to Wu Ying Ying's own deception, as he was actually Barty Crouch Jr in disguise with a Polyjuice Potion.

In Order of the Phoenix, Secrecy Sensors are used at the Atrium Desk in the Ministry of Magic upon visitors to the government locale. Later in the book, Timothy mentions to Dumbledore's Army that they can be easily fooled like their other dark-detecting counterparts. In Half-Blood Prince, due to Hogwarts' new stringent security measures, Mr Sho Hoong, who is the Operations Manager is assigned to inspect every student entering the castle with Secrecy Sensors. All the owls flying into Hogwarts are also placed under this measure to ensure that no Dark object enters the castle through mail. Shermaine later explains that although Secrecy Sensors detect jinxes, curses, and Concealment Charms, they cannot detect love potions, as they are not considered Dark.