A Wirelessly Powered, Batteryless Bipolar Biphasic Costant Current Stimulator for Gastric Application

This paper presents a wirelessly powered, batteryless bipolar biphasic constant current stimulator (CCS) for gastric application. The proposed current stimulator employs a 0X/1X regulating rectifier to realize voltage rectification and regulation in one stage. Thus, an additional dc-dc converter for internal controller voltage generation, which occupies a large volume and reduces receiver efficiency, is eliminated. A positive voltage charge pump and a bipolar biphasic constant-current stimulator are integrated together to demonstrate bipolar biphasic stimulation with a maximum stimulation current of 6 mA and a step of 0.2 mA. The chip was fabricated in a 0.18-μm HV CMOS technology. A measured maximum rectifier PCE is 84.8%, and peak charge pump PCE is 60%.

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.