Digital Fabrication of Frequency Selective Surfaces for In-Building Applications Using Inkjet Printing Technology

This thesis presents work on the inkjet printing manufacture of frequency selective surfaces intended for in-building applications using silver nanoparticle inks. The aim of this research is to investigate the performance of inkjet printed FSS panels in terms of transmission response, element conductivity, and the resolution of the printed lines, all of which are produced efficiently in terms of cost and resource usage. Different FSS design were investigated from simple elements such as linear dipoles, square loops and convoluted square loop elements. Various techniques were used in the manufacturing process such as different ink drop spacing, number of jetted ink layers, and different sintering methods, with the aim of achieving low cost manufacturing with a reduced amount of deposited silver inks and sintering time and temperature. Additionally, further reductions in the deposited ink were considered by the introduction of frame elements. The research also focuses on factors that could affect the transmittivity/reflectivity of the FSS screen, such as the influence of imperfections in the printed elements. The imperfections are expected in the case of low cost mass production, therefore it is important to understand to what extent they could be tolerated whilst still providing adequate performance. Finally, the work also considers developing novel slotted FSS arrays operating at low frequency bands such as the TETRA emergency band and suitable for additive manufacturing

Enhanced Read Range Tattoo RFID Tags

Transfer Tattoo RFID tags are described for person locating scenarios. The technology considered is Radio Frequency Identification (RFID) at the UHF Band where it is possible to obtain wireless connection over distances of several meters using passive, or battery assisted transfers. The tags have the profile of tattoos and can be mounted straight onto the skin. Promising results for enhancing read distances, possibly to tens of meters, have been obtained using very thin battery technologies

Inkjet Fabrication of Frame Dipole FSS

Digital fabrication techniques gives the possibility of producing elements with very thin and precise features which could allow the modification of UHF structures to reduce ink usage while still achieving similar performance. This paper investigates the case where dipole elements are modified into Frame Dipoles by removing areas where the surface current tends to be very low

Deficiencies in Printed FSS Intended for Application in Smart Buildings

Errors occur in the process of digital printing of frequency selective screens using conductive inks. This paper describes some of the defects observed during the printing process and investigates their effect on the resonance frequencies of arrays that might be fabricated in practice. The elements are simple linear dipoles. The presence of the classes of error described would be serious in the case of elements with complex geometries

Chemical Vapor Detecting Passive RFID Tag

A Radio Frequency Identification (RFID) Tag is designed for threshold detection of certain chemical vapors. The vapor presence is signaled to the reader by a digital alert and communication between the tag and reader is not interrupted. The detection mechanism comprises an inkjet printed conducting track on an elastomer that swells in response to vapor exposure. The expanded track breaks and triggers a tamper detection circuit integrated into the RFID tag transponder chi

Significant Factors in the Inkjet Manufacture of Frequency Selective Surfaces

Additive fabrication of electromagnetic structures by inkjet printing technology is both cost effective and compatible with a wide range environmentally-friendly substrates, enabling fabrication of frequency selective surface arrays with line dimensions less than 0.1 mm; difficult to achieve with conventional subtractive techniques. Several approaches have been investigated in order to produce low-cost frequency selective panels with acceptable level of isolation, such as savings in ink by depositing it at the edges of dipole elements where the surface current tends to maximize. The FSS transmission characteristics were improved by jetting multiple ink layers on the whole elements and at the edges. The electrical resistance of various arrays have been measured and analysed and has been used to assess the performances of the FSS

Inkjet printed paper based frequency selective surfaces and skin mounted RFID tags : the interrelation between silver nanoparticle ink, paper substrate and low temperature sintering technique Citation for published version (APA): Inkjet printed paper base

Inkjet printing of functional frequency selective surfaces (FSS) and radio frequency identification (RFID) tags on commercial paper substrates using silver nanoparticle inks sintered using low temperature thermal, plasma and photonic techniques is reported. Printed and sintered FSS devices demonstrate performances which achieve wireless communication requirements having a forward transmission scattering parameter, S 21 , depth greater than À20 dB at 13 GHz. Printed and plasma sintered RFID tags on transfer paper, which are capable of being mounted on skin, improved read distances compared to previously reported single layer transfer RFID tags fabricated by conventional thermal sintering

Study of Printing Errors in Digitally Fabricated FSS

Low cost fabrication techniques might give rise to defects in electromagnetic structures. This paper investigates the detrimental effect of producing frequency selective screens with differing percentages of absent square loop elements. It is shown that as many as one in five elements can be incomplete before the array transmission response is considered unusable

Study of Clusters of Defects in Low-cost Digitally Fabricated Frequency Selective Surfaces

Additive process fabrication of inexpensive FSS screens might lead to errors in the printing or to damage at installation owing to miss-handling. This paper investigates the introduction of clusters of missing elements in different locations and their effect on the performance of the arrays

UHF electromagnetic structures inkjet printed on temperature sensitive substrates: a comparative study of conductive inks and sintering methods to enable low cost manufacture

In this paper we demonstrate the use of inkjet printing as a facile digital fabrication tool for the cost effective manufacture of UHF RFID transfer tattoo tags and Frequency Selective Surfaces on low-cost flexible and porous substrates. Electrical and morphological properties of conductive features obtained from a range of metal nanoparticle inks and low temperature sintering methods, such as argon plasma and photonic flash, are evaluated. Large scale potential is addressed