We present a novel type of inter-module connection
mechanism for waterborne modular robotic systems. The
proposed mechanism exploits the thermoelectric effect to cool down and freeze the water between two modules thus causes them to attach to each other. We validate the feasibility of this mechanism by embedding a Peltier heat pump (m = 0.8 g) in two types of cm scale self-assembly systems, one in which the modules are free to move and one in which the modules are linked together by hinges. Our experimental results demonstrate that the proposed Peltier-based connector has (a) a high bond strength/weight ratio for a rather large range of temperatures and (b) is rather robust against misalignments between docking modules, making it a useful alternative to current connection mechanisms for small scale low autonomy self-assembly systems.