Abstract: Embodiments of the present disclosure are directed to miniature insulin patch pump, assistance devices (e.g., for reservoir filling and/or cannula insertion), and methods related thereto. For example, in some embodiments, a substance/drug-delivery patch pump is provided and includes a reusable part (RP) including a power source, a driving mechanism, and an electronic module, and a disposable part (DP), where the disposable part can include at least a plurality of an adhesive base, a reservoir, a dosing mechanism, and a cannula.