Grating and waveguide plasmonic sensors

Lead Research Organisation: University of Plymouth
Department Name: Sch of Computing & Mathematics

Abstract

Femtosecond lasers produce pulses of light which are extremely short and at the same time extremely powerful. The intensities available when light from such a laser is focussed down are capable of modifying the structure of transparent materials or even ablating material from the surface. We have developed an understanding of the interaction of fs laser pulses with optical glasses so that, depending on the pulse parameters, we can create light waveguides, couplers, bends and grating structures or even machine the surface to alter its topology on a micron scale.

In this project we wish to bring these capabilities together to create a generic plasmonic sensing technology. Surface plasmons are oscillations of the free electrons in a thin metal film and these can be generated using the energy from light travelling in a waveguide close to the metal film. Importantly, the transfer of energy from the light to the plasmon only occurs at a well defined wavelength which depends strongly on the refractive index in a micron thick region above the metal film where the electric field of the plasmon extends. By sending a broad spectrum of light though the waveguide near the metal film and noting which wavelength is absorbed by the device it is possible to measure the refractive index above the metal very accurately.

If chemical or biochemical specific coatings are applied to the metal film then the sensor can detect specific species. In this proposal we plan to investigate the use of aptamers in this regard. Aptamers are oligonucleotide sequences, which can be designed to bind to specific molecules, proteins, DNA sequences or even cells, providing a highly flexible sensing technology.

An additional application for the technology is as a means of monitoring cell movement and growth. Cells contact a surface at specific points and if a cell is placed on the plasmon supporting metal film, light will be scattered from the plasmon field at the points of contact. This light may be viewed using a microscope which will allow the movement of the cells to be tracked over time. Cells respond differently depending on surface topology and the fs laser can be used to modify the sensor surface to enable studies of the effect of different surface topologies on cell movement and growth.
 
Description We have developed a sensor based on an optical fibre or other waveguide that of itself provides very high sensitivity to refractive index. Importantly, the geometry of the device has allowed us to attach a variety of coating materials providing a specific response to target species. Two major demonstrations involving radically different coatings have been carried out so far.

Firstly we have shown that a coating of carbon nanotubes provides a specific detection of carbon dioxide at room temperature. This is the first utilisation of the optical properties of carbon nanotubes for this purpose and importantly opens up a range of applications as carbon nanotubes can be processed to respond to different gases.

Secondly we have used a coating of aptamers, which are short nucleic acid like molecules that can be synthesised in the laboratory to respond to a huge array of chemical and biochemical species. We have shown that our devices can detect concentrations of thrombin down to the 50 attomolar level without additional enhancement techniques and reveal real time kinetic behaviour. The selectivity of the technique has also been demonstrated using sequences of DNA. We have just published the final work in this series. it marks 3 years since the end of the extended grant, and highlights how difficult it is to gain follow-on funding.
Exploitation Route The sensing approach developed in this work is very generic and can be taken forward in many areas. Our current focus is on obtaining funding to develop sensors to provide real time, remote environmental monitoring of chemical and biochemical pollutants. We are still exploring opportunies with the agrichemicals sector.
Sectors Aerospace, Defence and Marine,Agriculture, Food and Drink,Chemicals,Environment,Healthcare,Manufacturing, including Industrial Biotechology,Pharmaceuticals and Medical Biotechnology

 
Description We have a 6 month extension until June 2016. I expect to contribute to this section next year. We have started exploitation through establishing partnerships in agriculture and medicine these last few years. We are continuing to explore possible projects with the University of Lincoln. Although the lack of full time contract with Tom Allsop, a key researcher in this work, hampers his focus on future projects. Tom is still awaiting a full time position in the UK, or the EU or China. He is currently a researcher in Spain. I find it outrageous that such a skilled physicist cannot find a permanent position here in the UK. He will be a significant loss to UK Plc.
First Year Of Impact 2015
Sector Agriculture, Food and Drink,Chemicals,Environment,Healthcare,Pharmaceuticals and Medical Biotechnology
Impact Types Economic

 
Description Aston University 
Organisation Aston University
Country United Kingdom 
Sector Academic/University 
PI Contribution Sensor device fabrication
Collaborator Contribution Assisting with experimental procedures for biochemical sensing
Impact Paper under review
Start Year 2012
 
Description Cyprus University of Technology 
Organisation Cyprus University of Technology
Department Department of Electrical Engineering,
Country Cyprus 
Sector Academic/University 
PI Contribution Preparation of sensor devices
Collaborator Contribution Assistance in fs machining of structures and sensor analysis
Impact "Photonic gas sensors exploiting directly the optical properties of hybrid carbon nanotube localized surface plasmon structures", Light: Science & Applications, 2016 "Highly sensitive, localized surface plasmon resonance fiber device for environmental sensing, based upon a structured bi-metal array of nano-wires", Optics Letters, Vol. 39, Issue 20, pp. 5798-5801, 2014. "Physical characteristics of localized surface plasmons resulting from nano-scale structured multi-layer thin films deposited on D-shaped optical fiber," Optics Express, Vol. 21 Issue 16, pp.18765-18776, 2013. "Formation and characterisation of ultra-sensitive surface plasmon resonance sensor based upon a nano-scale corrugated multi-layered coated D-shaped optical fibre", Jn. Quantum Electronics Vol. 48, No. 3 pp.394-405, 2012. "Localized surface plasmon fiber device coated with carbon nanotubes for the specific detection of CO2", SPIE Optics+Photonics, San Diego, USA, 2015 "An ultra-sensitive localised surface plasmon resonance fibre device for environmental sensing based upon a structured bi-metal coating", OFS23, Proc. SPIE Vol. 9157, 91574M, Santander, Spain, 2-6 June 2014. "Generation and performance of localised surface plasmons utilising nano-scale structured multi-layered thin films deposited upon D-shaped optical fiber", SPIE Optics+Photonics, Nanoengineering: Fabrication, Properties, Optics, and Devices X, San Diego, California, USA, 2013.
Start Year 2013
 
Description Florence 
Organisation University of Florence
Country Italy 
Sector Academic/University 
PI Contribution Designing and fabricating sensing platforms to take advantage of aptamer coating provided by collaborator
Collaborator Contribution Aptamer coating to render the devices highly selective. Specific detection of thrombin and DNA demonstrated.
Impact papers submitted to ACS
Start Year 2009
 
Description National Centre for Food Manufacturing 
Organisation University of Lincoln
Department National Centre for Food Manufacturing (NCFM)
Country United Kingdom 
Sector Academic/University 
PI Contribution Designing sensor for possible farming and agriculture applications
Collaborator Contribution Planning of experiments aimed to support future grant proposal
Impact Still at the point of planning experiments
Start Year 2015
 
Description Nottingham 
Organisation University of Nottingham
Department Department of Electrical and Electronic Engineering
Country United Kingdom 
Sector Academic/University 
PI Contribution Designing and fabricating sensing platforms to take advantage of molecular imprintin
Collaborator Contribution Coating our sensor platform with molecular imprinting medium
Impact none yet
Start Year 2014
 
Description UiT Norges arktiske universitet 
Organisation University of Bergen
Department Department of Physics and Technology
Country Norway 
Sector Academic/University 
PI Contribution Fabrication of sensor platform for coating
Collaborator Contribution Immobilisation of recognition molecules on the sensor
Impact Experiments currently in progress
Start Year 2012
 
Description University of Navarre 
Organisation University of Navarra
Country Spain 
Sector Academic/University 
PI Contribution Sensor design for testing molecular imprinting technique
Collaborator Contribution Discussion of experiments
Impact Experiments at discussion stage
Start Year 2015
 
Title Optical Fibre Gas Sensor 
Description A novel optic-fibre plasmon wave sensor has been developed and applied to ultra-low concentrations of test chemicals 
IP Reference GB2014/050213 
Protection Patent granted
Year Protection Granted 2014
Licensed No
Impact non yet