Cohen M., Kwok, G., and Cosic, I., Acupuncture Needles and the Seebeck Effect: Do Temperature Gradients Produce Electro-stimulation? Acupuncture and Electro-therapeutics Research. 22 No 1: 1997; 9-15.
Acupuncture may act through modifying bioelectric events and this may occur through different mechanisms including the application of external currents. According to the Seebeck effect which produces a potential difference when a temperature gradient is placed across a conductor, the physical properties of acupuncture needles may produce internal currents due to the temperature gradient across the needle when placed insitu. Such currents were detected when needles were differentially heated and these currents were found to be in the range capable of producing biological effects. The traditional design of acupuncture needles and traditional needle manipulations seem to maintain a temperature gradient across the needle and thus enhance the Seebeck effect.