5-figure14

Installation Ring and Modular Housing Concept

A flexible substrate carrying a bus for signal and power lines interconnecting the different building blocks of the sensor system will constitute the basis of the system. This flexible “backbone” of the system allows for a miniaturized storage when carried by the sewage robot and can be expanded during mounting to adapt to the interior of the sewer system. The system building blocks will be attached onto this flexible substrate. Here basically two technological variants can be of interest – for a highly integrated version with large robustness ensuring a long operation time the components will be assembled directly on the flex substrate and will then be encapsulated module by module. The system functionality, energy supply and sensor interfaces will all be integrated into the system before encapsulation, so system testing and calibration can take part at a step, where repair is still possible. For a more modular approach ensuring a high flexibility in integration of different sensors it is possible to assemble only the single functional blocks on flex or rigid PCB and introduce a flexible connector to link those submodules together. With this approach a premolded (possibly thermoplastic) housing will be used to protect the delicate electronics. From this modular approach cost effectiveness and higher versatility is expected. We expect a mixture of both variants: A highly integrated core system providing a set of basic functionalities (remote control, radio interface, battery, basic sensors) and application specific enlargements (energy harvester, additional sensors for a large bandwidth of chemical elements).

Technological challenges will involve cavity molding (e.g. cavities offers space for fluidic subsystem) in combination with removable caps allowing e.g. a change of the microfluidic system, sensor molding with free access of the sensor to the waste water, free form molding for flow optimised packages, electronic housing material toughened up for operation in sewage systems, concepts for tight, but flexible housings.

There is a close relationship between the construction of the ring assembly and the design of the thermal path (WP5) for the energy harvesting device. Choice of geometry, material and interconnection mechanism to apply the ring structure to the sewage pipe will limit the solution space for the technical setup of the thermal path. The interdisciplinary work at the ring assembly will bring together expertise from mechanical design for sewage pipe installations, thermal design for energy harvesting as well as microelectronic system assembly and packaging.