Printing technology can be used to fabricate conductive patterns, passive components, and passive microwave circuits. Printed conductors and tags were fabricated from materials which can be integrated as a part of clothing. Thus, they offer interesting possibilities, especially in wearable strain sensing applications. In novel printed electronics applications such as in printed RFID tag antennas, polymer thick film inks are used. Printed conductive polymer thick film (PTF) structures can be utilized in such sensors due to their strain sensitive nature. The chapter discusses a passive ultra high frequency (UHF) RFID system. Passive tags are light-weight, simple in structure, inexpensive, generally resistant to harsh environmental conditions, and they offer virtually unlimited operational lifetime. The chapter discusses the usability of PTF conductors and printed tags in practice. The effect of tensile strain on conductivity of PTF composites has been investigated by several scientists. When the polymer matrix composite is strained, several different phenomena are reported to occur.