Electrical stimulation for propelling endoscopes

Background: Methods are needed for propulsion of endoscopes and wireless vi deo capsules along the small intestine. This work aims to test the hypothes is that electrical stimulation could propel an endoscope by stimulating mus cular contraction. Methods: Prototype acrylic ovoid-shaped devices were constructed with 2 sta inless steel electrodes mounted on the tapered section, Five devices 15 to 23 mm diameter with a taper of 28 degrees to 40 degrees (included angle) we re tested. When these devices were in contact with the bowel wall, electros timulation was applied causing circular muscle contraction, which when appl ied to the taper of the ovoid resulted in forward propulsion of the device. The method does not induce peristalsis but works by stimulating local cont raction. The device was tested in the small intestine and esophagus of anes thetized pigs, Results: Electrostimulation caused the ovoid to advance rapidly (6 mm/sec) up and down the esophagus by inducing circular esophageal muscle contractio n. When stimulated at 15 Hz with 30-ms pulses, the threshold for movement i n the small intestine was 12 mA; at 20 mA the device moved reliably in eith er direction in the small intestine at speeds of up to 4.5 mm/sec and negot iated tight curves, Conclusion: Electrostimulation can move endoscopes in the small intestine.