Electrical properties of the conductive pigments for flexible antennas

The work provides information about using the new conductive pigments in flexible antenna technology. The electrical properties of the conductive inks and pigments are valued. The conductivity of the modern pigments is enough to transmit small signals in the wearable and flexible electronics. One of them is the pigment which consists of metal particles. A direct current (DC) resistance of the pigment layer is a few ohms/sq. We decided to use this pigment for design of flexible antenna. The microstrip patch antenna was created. The antenna was designed for operating in the 868 MHz Industrial, Scientific and Medical (ISM) band for short range communication to transmit the wearer's body temperature to a nearby base station. We made some electrical tests. The conductive layer parameters of the antenna were characterized by using the microstrip resonator method. The test shows quite low Q-factor of the antenna. It means that resistance of the pigments is too high for using it as the antenna conductor. Also, we measured microwave reflection and transmission coefficients of the pigment layer by using waveguide method. The results of the tests show that the pigments can be used as additional shielding to protect user from electromagnetic radiation of the wearable antenna.