Nanites

"Nanites" is a material that can be used to disable a speedster's connection to the Speed Force for a limited time. It was created by Ray Palmer sometime between 2014-2015.

Description
When a speedster is injected with Nanites, he partly loses his connection to the Speed Force for a limited time, disabling his ability to move at super speed.

However, Nanites can be disabled by the injected speedster if he vibrates his body at an incredible speed.

History
The Nanites were created by Ray Palmer sometime between 2014-2015. They were given to Oliver Queen for unclear reasons.

In 2015, to Barry Allen's request, Oliver (as Al Sah-him) came to Central City to help the Flash and Firestorm defeat the Reverse-Flash. During the fight, knowing that he can't beat the evil speedster while he can move at super speed, Oliver shot Reverse-Flash with a Trick arrow filled with Nanites, which made him enable to use his powers. He then explained to the speedster what it was before fighting him in hand-to-hand combat.

However, After he fell down, Reverse-Flash was somehow able to vibrate his body fast enough to disable the Nanites, thus giving him the ability to run again and attack the archer.

In 2018, after Iris West made Oliver (who she believed to be Barry Allen due to the reality change) faint by putting something in his drink, Oliver asked her what's going on, and she jokingly said that it's "Nanites courtesy of Ray Palmer", the same thing he said while fighting Reverse-Flash 3 years prior.

After Nora West-Allen went rogue, Barry suggested asking Ray for nanites in order to catch her and lock her up, although the rest of the team highly disagreed.

Behind the Scenes

 * The quote "Nanites, courtest of Ray Palmer", said by Oliver Queen in became an internet meme. Iris West quoting it again in  was a clear reference to the meme.