Piezoresistive sensors based on steel and other metallic substrates provide higher strain response than on standard ceramic substrates and are more easily packaged. But exposing high-strength steels to the standard high- temperature 850°C thick-film firing cycle affects their mechanical properties. In previous studies, we have developed a range of low-firing thick-film materials based on lead borosilicate glass, which allows processing at low temperatures. However, it is desirable to develop alternatives to potentially toxic lead-based glasses that to not include alkali metals, which degrade high-temperature insulation characteristics of dielectrics. To this end, this work concerns investigations in essentially substituting lead for bismuth, and presents a series of low-melting Bi-B-Zn-Si-Al oxide glasses having good stability against devitrification. However, these glasses, when formulated as thick-film pastes using standard vehicles based on ethylcellulose binders, were found to be quite sensitive to incomplete binder burnout, with strong bubble generation within the layer. Therefore, a novel organic binder based on polypropylene carbonate, featuring clean low temperature burnout, had to be introduced. On this basis, thick-film dielectric compositions have then been developed and tested, aiming to optimise the mechanical strength and their expansion matching with the steel substrates. In the goal of a complete materials system, first tests on compatible conductors and resistors, using the same glasses, are presented as well.