I. Introduction
Gastroparesis (GP) is a chronic debilitating gastric motility disease that causes vomiting, nausea, early satiety, weight loss, and abdominal pain [1]. GP is characterized by the irregular amplitude and frequency of the gastric slow waves, which affect myoelectrical activities in the stomach. Recently reports have confirmed that gastric electrical stimulation (GES) is effective for symptomatic relief [2]. The electrical stimulation is generally done by a current neuro-stimulator powered by a battery. The battery ensures a long operating time to reduce the frequency of unwanted re-surgery for battery replacement, which increases the risk of infection. However, the battery not only limits the volume of implantable medical devices (IMD) but also raises safety concerns against chemical reactions to the human body. Compared to employing the batteries in IMD, the wireless power transfer (WPT) technique can save lots of areas and avoid cyclical surgeries for battery replacement.