A Wirelessly Powered Implantable Stimulator IC for Relieving Gastroesophageal Reflux Disease

• Main Authors: Chiang, Che-Yi, 江哲儀
• Other Authors: Hong, Hao-Chiao
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/hd55s7

碩士 === 國立交通大學 === 電機工程學系 === 103 === Gastro-esophageal reflux disease (GERD) is one of the most common diseases that people nowadays suffer from. Irregular dietary habits, drinking too much caffeinated beverages, and being under high pressure are the main reasons that cause GERD. However, conventional medical treatments for GERD can only ease the symptoms but are not able to address the main cause of GERD. Furthermore, long-term medical treatments for GERD would probably lead to some side effects such as stomachaches, diarrhea, headaches, dyspepsia, and anorexia. An integrated circuit (IC) design of an implantable stimulator is proposed for GERD treatments in this thesis. By implanting the stimulator in the stomach of a GERD patient, the stimulator can generate proper currents to stimulate the lower esophageal sphincter (LES). Once the LES is electrically stimulated, it shrinks and thus blocks up the acid reflux. Therefore, GERD is effectively prevented. The stimulator generates current pulses with three different stimulating intervals according to the frequency of an input signal. The frequencies of 1.30 MHz, 1.32 MHz, and 1.34 MHz correspond to the stimulating intervals of short, middle, and long levels. The implanted stimulator is wirelessly powered and adopts the load-shift keying (LSK) modulation to transmit the sensed data back to the host. As a result, an off-chip transmitter containing a class-E power amplifier to ensure that the output signal power is large enough and a demodulator to demodulate the received data is implemented to cooperate with the stimulator. The proposed stimulator has been fabricated in a 0.35-um CMOS process. The total chip area is 0.865 by 0.904 mm2. The proposed stimulator and the class-E power amplifier consume 27.8 mW and 508 mW with a transmission distance of 5 cm, respectively. The measurement results show that the overall wireless power transfer efficiency is 5.5%.