Utilising graphene for biosensing

Lead Research Organisation: Newcastle University
Department Name: Mechanical and Systems Engineering

Abstract

From rapid, early diagnosis of disease to detection of biological and chemical agents in homeland security, food analysis and environmental monitoring, biosensor technologies are a front-line tool in the modern arsenal of point-of-need analytical systems. In the ever expanding area of biosensor development towards faster, cheaper, more accurate, more reliable sensor systems there has been an expanding interest in the exploitation of nanomaterials and, in particular, the employment of carbon nanotubes as transduction elements. Recently the emergence of the nanomaterial graphene, which is effectively an unrolled nanotube, has become an attractive alternative material as it has a number of significant potential advantages for exploitation in the biosensor arena. Due to the atomic thickness planar nature of graphene, sensors based on its unique properties have the potential to be extremely sensitive. Studies into the engineering/biological interface of graphene sensors thus open up the possibilities for a range of novel and exciting studies.Through the use of this flexible funding programme, the team will utilise the unique properties of graphene to investigate a series of feasibility studies directed towards biomedical applications. The project will kick off with an initial series of meetings between engineers and research groups in the Faculty of Medical Sciences to establish the project ideas exploiting graphene for biosensing. Preliminary discussions have already yielded a range of areas to be explored including point-of-care diagnostic systems and drug development. A variety of sensors will be fabricated on each wafer, thereby maximising the number of feasibility studies that may be explored during this project. Midway through the project and after initial results are obtained, each study will look to receive input from healthcare professionals, so further development of the technology may be targeted to current clinical needs. It is the ultimate aim of the project to assemble multidisciplinary teams to develop sensors demonstrating a step change in technology for clinical applications and move initial demonstrated concepts into prototype sensor systems.

Planned Impact

The proposed research will impact in the following domains: Policy Through the initial series of meetings (and the two following internal dissemination events), the management team would not only look to generate a initiate a series of experimental studies but also aim to establish widening interdisciplinary practises within the University. Researcher development Additional to the RAs directly employed on this project, all personnel involved with the projects would gain multidisciplinary research experience due to the very nature of the research activities proposed. Society Projects would address general healthcare diagnostics in areas such as drug discovery and point of care therapeutics and so in the long term, would look to increase the effectiveness of public health services and increase the quality of life in society as a whole. Although these are high risk feasibility studies, an indication of the possibilities of the technology would be gained by the first review meeting (month 8). Input from healthcare professionals and the Health Protection Agency will be sort at this review meeting so that these initial studies can then be targeted towards assessing suitability towards real clinical needs. Economy The ultimate goal of taking sensors from the lab into usable systems require extended multidisciplinary teams and the team would look at addressing this at the second dissemination event (month 16) with invites to academic, clinical and industrial stakeholders. Projects such as this are best suited to development of added value high end technology products and so it would be the intention to attract follow-on funding to develop prototype demonstrator systems and ultimately see direct financial benefits through licensing / spin out. In addition to these direct financial benefits, a step change in sensitivity of sensor technology would see early diagnosis of infection and disease with cost savings in prevention and cure. The technology platforms being develop are generic and therefore target applications could additional see future developments towards environmental monitoring and bio-detection for the defence industry, each with the associated economic benefits for this technology development. Knowledge dissemination The team would aim to publish in high impact journals (provisionally this would be aimed at Nano Letters) and conferences (provisionally aimed at IEEE MEMS).
 
Description The project aims were to address the fabrication of graphene sensors, establish projects across different teams to assess the feasibility of utilising graphene in biosensing applications and then to develop sensors to address these applications.

The first major challenge was sourcing suitable quality graphene. Three avenues were explored: i) exfoliation from Kish graphite, ii) purchasing CVD graphene situated on copper foil and then transferring to substrates of choice and iii) direct purchasing of transferred graphene on silicon/silicon oxide wafer substrates. Options (ii) and (iii) proved the most useful giving monolayer coverage. A range of projects were developed across the University ranging from exploring the mechanical and electrical aspects of graphene to developing diagnostic sensors and cell studies on graphene surfaces. From these initial project meetings, a series of sensor geometries were designed.

Sensors were fabricated by either incorporation of graphene into existing sensors or newly fabricated sensors based purely on graphene. For the latter, a MEMS foundry was used to process wafers purchased by option (iii) above. Developmental work was conducted on processing issues such as cleaning the wafers without damaging the graphene surface and the adhesion of deposited layers onto the graphene surface. A series of sensors were subsequently fabricated. Functionalisation of the sensors was performed by the pi-stacking association of pyrene molecules onto the graphene substrate. The pyrene molecule contained a terminal carboxyl group which allows crosslinking to a wide range of analytes.

Results to date include: characterising strain induced in graphene films through loading by a measurement of the Raman shift, an electroless plating technology to overcome the high contact resistance usually found with the traditional Cr/Au approach and giving a good adhesive electrical contact to the sensors, transferral of graphene onto interdigitated electrode arrays for biomedical sensing applications. All 3 projects were accepted for conference presentations. These provisional results look promising and work is continuing in these areas, together with cell based studies and additional characterisation work, through postgraduate research projects.
Exploitation Route The project has conducted pilot studies into various aspects of graphene, its properties and applications. The work is at an early stage but continues, currently through postgraduate research students. Developments from the project and of direct use are:
(i) Transferral techniques of graphene films onto sensor surfaces will be utilised to create hybrid graphene sensor technology from current sensor technology.
(ii) Protocols established for microfabrication of graphene devices will be utilised in future projects for high throughput manufacturing of devices.
(iii) Protocols established for functionalisation of graphene surfaces will be utilised in future projects on graphene based diagnostic systems.

Potential ways the outputs from this work can be used are:
(i) Electroless plating technology for use in the fabrication of graphene electronics.
(ii) Characterisation of strain effects in graphene utilised in strain engineering of graphene electronics.

The work has initiated both national and international networking opportunities and builds on researcher training in the field of graphene studies. The work ultimately acts as a basis for developing graphene based diagnostic technologies. In the longer term we would expect to see this work being used as the basis to develop healthcare products for general use.

The ultimate aim is to apply technologies based on graphene to healthcare and this project has indicated two areas where this looks feasible. In the area of diagnostic sensors, initial results look promising so graphene has the potential to impact on, for example, point-of-care diagnostic systems. Currently issues around graphene quality and effective system integration require attention before real benefits could be seen over what is currently available. In the area of cell work, cells have indicated a good affinity to graphene and so graphene sensors targeted towards cell study or modification of surfaces through graphene to promote cell activity show potential for high impact. The need to extract signals from the sensors developed in the project has driven work towards improving the electrical contact to graphene which not only impacts on this work but would support development of graphene based electronics.
Sectors Electronics,Healthcare

 
Description The project has conducted pilot studies into various aspects of graphene, its properties and applications. The work continues currently through postgraduate research student projects. Developments from the project which are currently of direct use in our group are: (i) Transferral techniques of graphene onto sensor surfaces are beng utilised to create hybrid graphene sensor technology from current sensor technology. (ii) Protocols established for microfabrication of graphene devices are being utilised in projects for high precision manufacturing of graphene devices. (iii) Protocols established for functionalisation of graphene surfaces are being utilised in projects on graphene based diagnostic systems. (iv) Electroless plating technology is continued to be developed for use in the fabrication of graphene electronics. The work initiated both national and international networking opportunities and built on researcher training in the field of graphene studies. The work ultimately acts as a basis for developing graphene based diagnostic technologies.
First Year Of Impact 2012
 
Description Leverhulme Visiting Professorship
Amount £78,307 (GBP)
Funding ID VP1-2013-003: Biswajit Ghosh 
Organisation The Leverhulme Trust 
Sector Academic/University
Country United Kingdom
Start 07/2014 
End 06/2015
 
Description UKIERI Trilateral Research in Partnership
Amount £50,000 (GBP)
Funding ID UKIERI-TRP-2012/13-0010 
Organisation British Council 
Sector Charity/Non Profit
Country United Kingdom
Start 03/2013 
End 02/2015
 
Description Biswajit Ghosh 
Organisation Jadavpur University
Country India 
Sector Academic/University 
PI Contribution Lab assistance followed by joint author on paper and contributor to a British Council TRIP application.
Collaborator Contribution 1 week of lab assistance followed by joint author on paper and contributor to a British Council TRIP application.
Impact Conference paper presented at Nanotech 2012. British Council TRIP application successfully applied for. Multi-disciplinary: mechanical engineering, electrical engineering, chemistry, physics
Start Year 2011
 
Description Advanced Functional Materials (AFM) conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Mr Bamford presented a poster on techniques for ink jet printing of graphene which initiated discussion about the work.
Year(s) Of Engagement Activity 2015
 
Description Seminar (Exeter) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact Seminar given to the graphene research group at Exeter University.

Working with Exeter on development of graphene based biodevices.
Year(s) Of Engagement Activity 2012