This embodiment relates to portable handheld medical devices and in particular to handheld devices functioning without batteries. The medical devices connect to an external system and receive power. The external system may refer to any of everyday devices like a laptop or a mobile phone and so on. The medical devices operate once the power source i.e. the external device is connected. The medical devices can be shut down after use and connection between the external system and handheld medical devices is removed.
