We describe a technique for measuring a Seebeck effect in gels and present data for three systems. notably distinct signals are obtained for gel originating in the electrosensitive organs of marine sharks, syntehtic collagen-based gel, and as a control, seawater, the gels' seawater simply confirms that gels suppress mass transport. The difference between synthetic gel and the gel of sharks shows that the charged polymers of the shark gel restrict mass transport much more successfully than the polumers of the collagen gel, and we submit that this sort of ion localization is key to the emergence of thermoelectricity in a gelatinous substance. We compare the properties of the natural gel to those of established thermoelectrics.
Brown, Brandon R., "Thermoelectricity in Natural and Synthetic Hydrogels" (2004). Physics and Astronomy. Paper 25.