Sonic pen
From Tardis Wiki, the free Doctor Who reference
The Sonic pen was a sleek black device used by Matron Cofelia that functioned in a similar fashion to the Doctor's sonic screwdriver, but looked more or less like a pen. In discussing the similarities and differences between the sonic pen and sonic screwdriver the Doctor implied both were of similar manufacture. The Sonic Pen was able to open deadlock seals in the Adipose Industries Headquarters. It is unknown whether or not the device also functioned as a pen.
The Doctor later threw the sonic pen into a bin. It is unknown what has happened to it after that. Fans thought it may be used later in the series, but was found out to be wrong. (DW: Partners in Crime)
