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In this paper, the feasibility of inkjet printing of circuit and microwave structures on paper-based substrates is investigated for the first time in the implementation of a complete low-cost wireless platform for sensors. First, the system-level design of the module including the amplifier characterization were carried out to ensure optimum performance of the sensor modules in the UHF bands used in RF identification communication. These results were then used to design two different antenna structures, which are printed on paper along with their respective circuit layouts using inket-printing technology. Different techniques were investigated for the assembly of circuit components on the silver printed layouts. Finally, wireless link measurements on the assembled prototypes verified the good performance on the wireless and sensing sides. Index Terms--Antenna, assembly, dipole, inkjet printing, micro-controller, monopole, paper, power amplifier (PA), RF identification (RFID), sensor, temperature, transmitter, ultra high frequency (UHF), wireless.

In this paper, inkjet-printed UHF and microwave circuits fabricated on paper substrates are investigated for the first time as an approach that aims for a system-level solution for fast and ultra-low-cost mass production. First, the RF characteristics of the paper substrate are studied by using the microstrip ring resonator in order to characterize the relative permittivity ([[epsilon].sub.T]) and loss tangent (tan [delta]) of the substrate at the UHF band for the first time reported. A UHF RFID tag module is then developed with the inkjet-printing technology, proving this approach could function as an enabling technology for much simpler and faster fabrication on/in paper. Simulation and well-agreed measurement results, which show very good agreement, verify a good performance of the tag module. In addition, the possibility of multilayer RF structures on a paper substrate is explored, and a multilayer patch resonator bandpass filter demonstrates the feasibility of ultra-iow-cust 3-D paper-on-paper RF/wireless structures. Index Terms--Cavity resonator, dielectric characterization, inkjet printing, loss tangent, low-cost RF modules, multilayer, paper, printable electronics, relative permittivity, resonator bandpass filter (BPF), RF identification (RFID), ring resonator, UHF, wireless local area network (WLAN).

Anxiety is a fundamental aspect of the human experience. It can be an adaptive response to a perceived threat, with both psychological and physiological features. In the short term, anxiety [...]