Is it permissible for me, as a blind person, to place my hand on the head of an unfamiliar woman during Ruqyah Shar'iyyah (Islamic exorcism/healing), in order to observe the vibrations and movements of her body, in the same way that sighted exorcists observe these with their eyes?

The ruqyah practitioner must be pious and avoid prohibitions in ruqyah. It is not permissible for thej ruqyah practitioner to look at 'awrah (private parts), and touching the 'awrah is even more prohibited. It is not permissible for the ruqyah practitioner to touch a non-mahram woman, whether directly or through a barrier, due to the potential for fitna (temptation/strife) that results from it. Some women or the mahrams of the woman receiving ruqyah can be enlisted to observe her condition during the ruqyah.