Is there a massaging device that can help me regain nipple sensation?

It's extremely uncommon for nipple sensation to not gradually return after breast surgery. Most of the time the sensation will come back in 3-5 months but in some cases, it may even be longer around 12 months. I don't recommend massagers. Please continue with the massage technique your surgeon showed you and hopefully you regain the sensation soon. Best wishes.

Dear Philosophical658857,
I understand your concern. It is best that you consult your plastic surgeon regarding post operative care and management (i.e including massage techniques and timing) specific to your case. Your surgeon knows your condition well and has preferences on when and what to use for faster healing and recovery. Post operative care and management depends on the type of surgery performed and the technique used during surgery among other factors.It is best, however, that you follow your plastic surgeon's advice on post operative care management for a smooth and faster healing and recovery.
Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

Regaining sensation is more a factor of time and if the small sensory nerves will recover or not. If you are at one year out from surgery, you will not regain sensation.