Digital Fabrication of UHF Electromagnetic Structures

Lead Research Organisation: University of Kent
Department Name: Sch of Engineering & Digital Arts


Radio Frequency Identification (RFID) technology uses radio waves to communicate between wall-mounted or handheld reading devices and small unobtrusive labels. RFID has greater potential than commonly used barcodes and is increasingly used to track the whereabouts of everyday items as they move through, eg, a factory or supermarket. Obviously, if they are to compete with barcodes, they must be very cheap and printed in one way or another. Very thin tag designs must work sufficiently on different objects. Fabrication technologies need to be evolved to make the RFID integrated circuit connection cheaply and easily.
Although RFID has been used to illustrate the concept of printed tags, it is envisaged that skin transfer antennas could also be designed with the terminals connected by surgical plaster. Longer term possibilities involve putting high impedance surfaces directly onto the skin to manage the radio channels around the body, and even facilitate personal stealth where the visibility of a person to radar could be altered to avoid detection in a military scenario. The technology could also be applicable for medical sensing and as a pick up for implanted devices. The human body is an especially challenging platform for RFID owing to its high conductivity. Human tagging, external to the body, is usually based on wrist bands or ID badges which can be removed and given to other people. A design concept outlined in this proposal is a thin, platform insensitive UHF RFID tag that can be mounted directly onto the skin surface in the form of a transfer patch in much the same way that a temporary tattoo could be applied. This work is at an early stage and requires research into effective inkjet printing of the tag pattern onto the transfer material and reliable mounting of the tag Integrated Circuit.
The next ten years will see a rapid gain in market share of mainstream printed RFID tags. According to 'Printed and Chipless RFID, Forecasts, Technologies & Players 2011-2021' (by IdtechEX), the numbers sold globally will rise from 12 million in 2011 to 209 billion in 2021. By value, chipless versions will rise from less than $1.38 million in 2011 to $1.65 billion in 2021, about one fifth of all income from RFID tags in 2021 because most of the increase in penetration will be by price advantage'.

Frequency Selective Surfaces (FSS): The radio spectrum is a finite resource and just as is the case with oil and gas and other fuel supplies, the expanding economies are making ever increase use of it. But whereas with oil and gas the total amount that might be available is uncertain, with new fields discovered from time to time, the extent of the radio spectrum is limited. Almost everyone now has a mobile phone and a wireless computer, whether at home or in the office. They all use radiowaves to communicate with each other and so all have the potential to interfere with each other. In buildings, the walls and office furniture hinder efficient communications but at the same time are often insufficiently hindering to prevent unwanted evesdropping. FSS are flat pieces of thin material somewhat like wall paper with printed patterns. These patterns if drawn correctly have the potential to either enhance or seriously reduce the travel of radiowaves from place to place in the building. In other words they influence the electromagnetic architecture of the buildings. By careful configuration this means that more computers can be installed in a building without interacting with each other if that is required, while at the same time unwanted interference from other computers or other cell phones can be reduced improving the speed of broadband provision and avoiding lost phone calls.

Inkjet conducting ink processes will make these technologies inexpensive and widespread.

Planned Impact


Temporary Secure RFID
The technologies developed here would benefit operators of secure environments such as government buildings, airports and prisons, providing them with secure temporary ID that cannot be transferred to other individuals such as passenger, visitors or shift workers requiring access for a limited time. Also benefiting are operators of secure ticketing or where it would be undesirable to insert sub-skin RFID capsules. Healthcare providers would benefit from cheap, hygienic and reliable disposable wireless pickups for implanted devices. There is a serious problem with ticket sales for popular events where 1 in 12 customers have been defrauded by counterfeit and resold tickets:
[]. The proposed technology could provide tickets that cannot be exchanged or counterfeited and could have wide application. The military and emergency services could benefit from skin mounted electromagnetic structures, including FSS arrays, allowing their body centric communication systems to work more efficiently by adding high impedance surfaces.

Frequency Selective Surfaces in the Built Environment.
In-building telecommunications requires a range of services in bands extending from 400MHz to above 5GHz. The availability of a commercially viable method for producing inexpensive bespoke wall paper printed with conducting patterns which would act as filters for electromagnetic waves at the frequencies typically used for WLANs and mobile systems would be of great interest and benefit to users and suppliers of wireless systems. This would impact the whole supply chain from ink manufacturers, printers, architects, building constructors and end users. The end users, i.e. the occupiers, of such buildings would benefit through the services provided. The owners of buildings enhanced by the proposed technology could be commercial, such as airport or office operators, cinemas and theatres, where access to the emergency services band is required, but suppression of mobile phone signals may be desirable, or in the public sector such as prisons and government.
We are aware of enquiries in this area from cinema and theatre managers. The cost of present day theatrical productions is so great that the expenditure involved in improving the electromagnetic architecture of theatres is proportionally nowhere near as high as might be thought. In short, any organisation interested in improving the efficiency of spectral use by careful configuration of the EM architecture of the built environment is a potential beneficiary.


Printed worn RFID tags offer improved security with less personal intrusion, as biometric sensing techniques may not be required, for example in airports. Secure access could be achieved robustly without the need for injection of sub skin transponders, for example as proposed for computer login technology. Also, the significant fraud problems associated with ticketing of public events could be reduced by skin tagging. In the health sector, substituting skin mounted pickups for conventional strapped and wired sensors would lead to improved patient experience and better hygiene. Deployment of FSS would provide not only more reliable wireless access in new and old buildings, but in their signal attenuating mode could, for example, offer reduced risk of crime coordinated from within prisons. We have been contacted by the local prison services in this regard and have also liaised with the Home Office Scientific Development branch. Public safety would be improved with enhanced penetration into buildings for the Airwave provision for emergency services. Of course, entertainment has a very strong social impact as well as its importance economically. Cinema and theatre owners would be able to apply the technology to reduce audience disturbance from mobile phones.


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Batchelor JC (2015) Inkjet printed ECG electrodes for long term biosignal monitoring in personalized and ubiquitous healthcare. in Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference

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Gu C (2017) Dual-Band Electronically Beam-Switched Antenna Using Slot Active Frequency Selective Surface in IEEE Transactions on Antennas and Propagation

Description This project has developed a silver ink inkjet technique for printing RFID tags onto temporary tattoo transfer paper. The tattoo transfers have been demonstrated to work and are currently still comparable with the latest epidermal RFID tag efficiencies.
Exploitation Route The transfer tattoo tags developed in this project form the communications platform basis of new wireless battery free skin based sensing technologies. They have already been investigated through contract with DSTL and development continues to make the tags into conformal and cheap devices for long term monitoring in health and social care.
Sectors Aerospace, Defence and Marine,Agriculture, Food and Drink,Construction,Digital/Communication/Information Technologies (including Software),Electronics,Healthcare,Manufacturing, including Industrial Biotechology,Security and Diplomacy

Description Kent work on passive UHF RFID tagging began with the requirement to develop structures that could be mounted on conducting surfaces or on liquid filled bottles without a drastic reduction in read range. At the time (2004), UHF tag read ranges were limited to about 3m at permitted European reader EIRPs. We investigated tags that could read as they were tuned for certain surfaces and this work has evolved to create designs that will work on different surfaces - so called surface independent tags. We have addressed the issue that alternative designs of tags for use on conducting surfaces are usually several millimetres thick. Research at Kent produced designs significantly thinner than 1mm which could be treated as labels. Other, commercially available, tag designs also existed, but these would not work well when attached to challenging surfaces such as metals or skin, whereas the Kent designs would. Tagging people is becoming a useful application, for simple ID (e.g. hospital patients), or security (e.g. government buildings) or for ticketing (club admission). The human body is especially challenging for radio systems mounted on the surface. Our research has developed tags that can work close to, or mounted on, the skin, and in the extreme we have developed a transfer tattoo RFID tag with a moderate read range. The tattoo tag is in the prototype stage but health and defence collaborators are advising us on how to develop it for their needs when fabrication by printing is perfected. Ultimately this work should be applicable to the TSB identified theme of the 'Internet of Things', where many devices will become enabled with wireless communication to exchange data. New techniques have been developed at Kent to tackle the problems of radio propagation in the built environment and specifically into buildings. These problems are manifest in the well-known situations of poor reception inside walls. This is particularly problematic for emergency services where a lack of communication can literally cost lives. There is also a related worldwide problem of prisoners illicitly using mobile phones to coordinate crime and for witness intimidation. There are documented occurrences of murders being arranged by mobile phone from inside prisons. Also, WiFi computer access is now regarded as a necessary service for business, especially when travelling and increasingly ordinary leisure users expect a continual and reliable wireless data link. There are problems achieving this where high channel demand saturates the bandwidth available and datarates either fall very low or access is denied altogether. This can be alleviated by providing screens to block radio signals, and indeed modern buildings do contain metal foils in cavity walls (for insulation and moisture blocks). However, these foil sheets will screen all radio including mobile phones and emergency services - a problem that is contributed to by tinted glass facades. Underpinning research at Kent seeks to address these problems with the development of Frequency Selective Surfaces to pass desired radio bands and reflect others, [2-3]. These structures have been investigated for their performance at a range of incident ray angles and for the amount of power they pass when a panel of a certain size is mounted in a foil covered wall. Different FSS lattice structures and elements including highly convoluted and interleaved designs have been researched to offer correct bandwidth, roll-offs and multiband spacing. We received visits from 3 international researchers as part of this project.
First Year Of Impact 2012
Sector Aerospace, Defence and Marine,Agriculture, Food and Drink,Construction,Digital/Communication/Information Technologies (including Software),Electronics,Healthcare,Manufacturing, including Industrial Biotechology,Security and Diplomacy
Impact Types Economic

Description Advanced Manufacturing Supply Chain Initiative (AMSCI)
Amount £7,000,000 (GBP)
Funding ID 33084-233301 
Organisation Birmingham City Council 
Sector Public
Country United Kingdom
Start 06/2015 
End 03/2018
Description Authenticated Self
Amount £115,958 (GBP)
Funding ID 44156-323132 
Organisation Innovate UK 
Sector Public
Country United Kingdom
Start 04/2015 
End 03/2018
Description CDE Finding the Threat
Amount £59,805 (GBP)
Funding ID CDE30142 
Organisation Defence Science & Technology Laboratory (DSTL) 
Department Centre for Defence Enterprise
Sector Public
Country United Kingdom
Start 02/2013 
End 08/2013
Description DSTL Contract
Amount £29,966 (GBP)
Funding ID DSTLx 1000077663 
Organisation Defence Science & Technology Laboratory (DSTL) 
Sector Public
Country United Kingdom
Start 01/2013 
End 04/2013
Description Manufacturing the Future
Amount £1,289,916 (GBP)
Funding ID EP/R02331X/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 04/2018 
End 03/2021
Description Manufacturing the Future
Amount £1,305,276 (GBP)
Funding ID EP/P02713X/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 08/2017 
End 07/2020
Description Manufacturing the Future
Amount £441,579 (GBP)
Funding ID EP/L019868/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 06/2014 
End 06/2016
Description Access Wireless 
Organisation Access Wireless
Country United Kingdom 
Sector Private 
PI Contribution Engagement with Access Wireless Ltd to understand the needs of civil and consumer communications limitations and suitable building infrastructure adjustments that might be made.
Collaborator Contribution Attendance at progress meetings and expert advice.
Impact Outcomes of this collaboration are internal to the project team.
Start Year 2012
Description DSTL 
Organisation Defence Science & Technology Laboratory (DSTL)
Country United Kingdom 
Sector Public 
PI Contribution Engagement with collaborators to understand the security needs of skin mounted communications (reducing the burden on the soldier) and provision of secure screening within defence related buildings.
Collaborator Contribution Attendance at project progress meetings and expert advice on military matters. Also access to test equipment and materials and advice on test scenarios that affect the project.
Impact Outputs include 2 follow-on contracts directly funded by DSTL. Also sponsorship of student projects at the University of Kent. The research team was invited to present to the DSTL Antennas Working group in 2013.
Start Year 2010
Description Great Ormond Street Hospital 
Organisation Great Ormond Street Hospital (GOSH)
Country United Kingdom 
Sector Hospitals 
PI Contribution Engagement with partners to appreciate the special requirements of long term monitoring of complex juvenile patients.
Collaborator Contribution Advice and guidance regarding the possible clinical benefits of this technology within a healthcare environment and to attend progress meetings. Also leading a seminar at Kent on Neuro-clinical procedures and techniques in children. Senior Clinical Engineer Alan Worley has been awarded visiting status at the University of Kent.
Impact Broadcast coverage on BBC Radio5 live and Good morning Scotland.
Start Year 2012
Company Name Evidentia Ltd 
Description Evidentia is an SME specialising in security technologies for the security sector and new sensing technologies for public and government services. 
Year Established 2007 
Impact Funding awarded from CDE and Innovate UK to transfer epidermal tagging for covert use, and secure authentication for communications and contactless payment systems.
Description Press Release on tattoos 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Media (as a channel to the public)
Results and Impact The initial press release for a new EPSRC grant generated live broadcast interviews with BBC Radio Kent, 5Live and Good Morning Scotland.
Subsequent work formed part of a recorded interview on plant theft protection broadcast on BBC Radio 4's Costing the Earth.

National scale awareness of the use of printed RFID as a passive tracking system.
Year(s) Of Engagement Activity 2011,2012,2014
Description Smart Buiding Outreach talks to Kent schools 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact The talk provoked questions from interested pupils with several enquiring about further study in Engineering. One school requested a repeat of the talk for a larger audience.

One school requested a repeat of the talk for a larger audience. Another school reported that a pupil was disappointed to discover she could not continue to an Engineering degree as she had dropped maths.
Year(s) Of Engagement Activity 2007,2008,2009,2010,2011
Description Transport Expo 2014 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Invitation to give a showcase demonstration at the national Transport Security Expo 2014. The purpose was to describe and demonstrate epidermal tagging technology originally developed under EPSRC funding. The audience comprise around 40 attendees from mainly professional and government agency sectors.
Year(s) Of Engagement Activity 2014