Reference: al-Muntaqaa min Fataawa Shaykh Saalih al-Fowzaan – Volume 5, Page 14, Fatwa No.12
Question: The [issue of a] woman touching a man without any intention such as her passing through a busy place or the like, or her receiving something from a seller such as [some] goods and she hands him over the money or the like, does this form of touching nullify her wudhoo if she previously had wudhoo or does it not have any effect [on her wudhoo]?
Response: Firstly, we advise the woman not to get caught in busy places with men and to keep far away from mixing and [unintentional] touching of the men keeping far away from busy places where there is fear of fitnah, because indeed the woman is a [source of] fitnah – causing fitnah for herself and others, so it is obligatory upon her to keep far away from places of fitnah.
As regards her having touched a man without intention, such as that which was mentioned [in the question], then the correct [opinion] from the statements of the people of knowledge is that this does not nullify her wudhoo, rather her wudhoo is nullified if she touched him with desire or he touched her with desire as we have mentioned [before].