Anisotropic Liquid Dielectrophoresis and Interfacial Forces

Lead Research Organisation: University of Strathclyde
Department Name: Mathematics and Statistics

Abstract

There is a growing technology-driven interest in using external influences to move or shape small quantities of liquids, a process that is referred to as "microfluidic actuation". Using electrical, rather than mechanical, forces to achieve this actuation is convenient because this involves relatively simple device architectures that contain no moving parts. Existing non-mechanical microfluidic actuation techniques that are driven by the application of a voltage include electrowetting, which only works with conducting liquids, and dielectrophoresis, which works with both conducting and non-conducting liquids. We have previously shown how dielectrophoresis forces in non-conducting isotropic liquids can be used to create not only forced wetting and liquid spreading, but also liquid film wrinkling in which an engineered electric field distribution imprints a replica of itself as a distortion pattern at the liquid-air interface of the film. In this proposal the possibility that liquid dielectrophoresis can lead to added functionality and greater control within a pure anisotropic liquid, i.e. a nematic liquid crystal rather than a simple isotropic liquid, will be investigated. Liquid dielectrophoresis in pure anisotropic liquids has not been studied before, either experimentally or theoretically. Our proposed integrated collaborative experimental and theoretical research approach aims to understand and exploit the forces that can be created within, and at the surface of, free and confined anisotropic liquids when they are subject to electric fields. The proposed research will investigate an exciting new possibility of using anisotropic liquids along with particular confinement geometries which allow voltage controlled actuated microfluidic pumping to be produced even with simplified electrode architectures. Our industrial supporters include Merck Chemicals Ltd, the world-leading researcher, developer and manufacturer of liquid crystals and reactive mesogens, together with Hewlett-Packard and ADT, who are developing the next generation of information displays based on liquid crystal and microfluidic effects.
 
Description New knowledge and methods generated: (1) We have shown that the deformation of hemispherical droplets of a conducting liquid by the electric field in a capacitor obeys a scaling law in which the change in droplet height is proportional to the square of the electric field and the square of the radius of the droplet at its base. We have developed equations which also explain and describe the experimental dependences of this static deformation on the electric field and on the length-scales in the system when the droplet deviates away from an initial hemispherical shape. We have further explained and quantified the time dependent processes by which the droplets deform immediately after an electric field is applied on short timescales, which is dominated by electric and surface tension effects, before the longer timescale response which is dominated by surface tension and viscosity effect. (2) We have developed a new relatively simple and compact manometer geometry with an applied electric field which allows a complete investigation of the competition between flow and electric field alignment in a nematic liquid crystal. Normally an electric field applied across a layer of nematic liquid crystal causes the molecules to reorient towards the direction of the electric field when a voltage above a critical value is applied to the plates that confine the liquid crystal - this is the well-known Freederiksz effect. We are able to use electrical forces to draw the nematic liquid crystal into one arm of the manometer and then remove the voltage so the height difference between the two arms decays back towards zero providing access to a range of shear/flow rates in a single experimental run. During this decay we have been able to observe, and explain theoretically, how the flow delays Freedericksz transition to higher voltage. (3) We have shown how to electrically induce spreading of drops of nematic liquid crystals to create forced wetting on a solid surface. We have quantified and can explain the observed voltage dependence for conventional nematic liquid crystals at different temperatures, and for highly dispersive nematics at different frequencies of the applied voltage. When the droplet has been driven into a film we can create a periodic surface deformation. The research has generated new insight into the role of the alignment of the molecules in the liquid, and associated internal elasticity, in both the spreading and the wrinkling phenomena. We are finishing work to further develop these techniques to provide a new method to observe the effects of, and quantify, certain physical parameters that are usually difficult to measure in nematic liquid crystals.
Exploitation Route This work could be developed in may possible directions, including new and improved methods for manipulating small droplets of liquid crystal, development of tunable micro-lenses, and new methods for measuring certain parameters which are normally difficult to measure in liquid crystals.
Sectors Aerospace, Defence and Marine,Chemicals,Digital/Communication/Information Technologies (including Software),Electronics,Energy,Manufacturing, including Industrial Biotechology

 
Description From Carrot Juice to TVs: the story of liquid crystals - video This is the story of how a simple experiment on carrot juice led to the revolution in TV technology, leading to large flat screen displays used around the world. This video was created by Wiretrace (www.wiretrace.net) and the project team at the University of Strathclyde (Drs Lindsey Corson, Brian Duffy, Profs Nigel Mottram, Stephen Wilson) and Nottingham Trent University (Prof. Carl Brown and Dr Costas Tsakonas) as part of the "Anisotropic Liquid Dielectrophoresis and Interfacial Forces"project funded by the EPSRC (EP/J009873/1). Images were kindly provided by Dr Stephen Cowling, University of York.
First Year Of Impact 2015
Sector Creative Economy,Education,Other
Impact Types Cultural

 
Description EPSRC iCASE Studentship with Merck (Chemicals) Ltd
Amount £70,000 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 10/2016 
End 10/2020
 
Title Experimental data for dynamic response of a thin sessile drop of conductive liquid to an applied voltage 
Description Experimental data and analysis file for dynamic response of a thin sessile drop of conductive liquid to an applied voltage. The dataset comprises of one Excel file which contains data on height changes against time for a twenty voltages and one Matlab file used to extract and analyse the data in the Excel file. 
Type Of Material Database/Collection of data 
Year Produced 2016 
Provided To Others? Yes  
Impact Not recorded 
 
Title Flow-induced delayed Freedericksz transition 
Description CSV data and Matlab file for figures in "Flow-induced delayed Freedericksz transition" published in PRE 2016 
Type Of Material Database/Collection of data 
Provided To Others? No  
Impact Not recorded 
 
Description Joint research with Nottingham Trent University 
Organisation Nottingham Trent University
Country United Kingdom 
Sector Academic/University 
PI Contribution University of Strathclyde researchers worked on this project with researchers from Nottingham Trent University.
Collaborator Contribution University of Strathclyde undertook the theoretical analysis and computations. Nottingham Trent University undertook the physical experiments.
Impact Recently we were awarded and EPSRC iCASE award with Merck (Chemicals) Limited which arose directly from our collaboration with Nottingham Trent University.
Start Year 2012
 
Description 13th European Conference on Liquid Crystals 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presenter: Antariksh Saxena. Title: Anisotropic dielectrophoresis - nematic liquid crystals. Meeting: 13th European Conference on Liquid Crystals
Venue: University of Manchester, Manchester. Dates: 7th to 11th September 2015.
Year(s) Of Engagement Activity 2015
 
Description 13th European Conference on Liquid Crystals 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presenter: Nigel Mottram. Title: Bending, flexing, wrinkling and snapping of droplets and films of isotropic and nematic liquids. Meeting: 13th European Conference on Liquid Crystals. Venue: University of Manchester, Manchester. Date: 7th to 11th September 2015.
Year(s) Of Engagement Activity 2015
 
Description 18th European Conference on Mathematics for Industry (ECMI 2014) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Type Of Presentation paper presentation
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presenter: Nigel Mottram. Title: Deformation of liquid drops and thin films under the influence of an electric field. Meeting: 18th European Conference on Mathematics for Industry (ECMI 2014). Venue: Taormina, Italy. Date: 9th to 13th June 2014.



Not recorded
Year(s) Of Engagement Activity 2014
 
Description 1st International Conference on Micro and Nanofluidics (Flow 14) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Type Of Presentation paper presentation
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presenter: Stephen Wilson. Title: Electric field induced deformation of sessile droplets. Meeting: 1st International Conference on Micro and Nanofluidics (Flow 14). Venue: University of Twente, The Netherlands. Date: 18th to 21st May 2014.



Not recorded
Year(s) Of Engagement Activity 2014
 
Description 26th Scottish Fluid Mechanics Meeting 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Type Of Presentation paper presentation
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Presenter: Lindsey Corson. Title: Liquid dielectrophoresis and wrinkling on the surface of a fluid layer. Meeting: 26th Scottish Fluid Mechanics Meeting. Venue: University of Aberdeen. Date: 29th May 2013.



Not recorded
Year(s) Of Engagement Activity 2013
 
Description 27th Scottish Fluid Mechanics Meeting 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Type Of Presentation paper presentation
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact Presenter: Lindsey Corson. Title: Deformation of nearly hemispherical drops of conducting fluid by an electric field. Meeting: 27th Scottish Fluid Mechanics Meeting. Venue: University of St Andrews. Date: 15th May 2014.



Not recorded
Year(s) Of Engagement Activity 2014
 
Description 28th Scottish Fluid Mechanics Meeting 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Presenter: Lindsey Corson. Title: Spontaneous wrinkling of a layer of nematic liquid crystal. Meeting: 28th Scottish Fluid Mechanics Meeting. Venue: University of Glasgow, Glasgow. Date: 28th May 2015.
Year(s) Of Engagement Activity 2015
 
Description 67th Annual Meeting of the APS Division of Fluid Dynamics 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Type Of Presentation paper presentation
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presenter: Lindsey Corson. Title: Electric field induced deformation of sessile drops. Meeting: 67th Annual Meeting of the APS Division of Fluid Dynamics. Venue: San Francisco, California, USA. Dates: 23rd to 25th November 2014.



Not recorded
Year(s) Of Engagement Activity 2014
 
Description 6th International Workshop on Bubble and Drop Interfaces 2015 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presenter: Carl Brown. Title: Anisotropic dielectro-wetting - nematic liquid crystals. Meeting: 6th International Workshop on Bubble and Drop Interfaces 2015. Venue: Potsdam/Golm, Germany. Dates: 6th to 10th June 2015.
Year(s) Of Engagement Activity 2015
 
Description Anisotropic Dielectrophoresis - Nematic Liquid Crystals 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presenter: Carl Brown. Title: Anisotropic Dielectrophoresis - Nematic Liquid Crystals. Meeting: 9th International Meeting on Electrowetting and Related Micro/Electrofluidic Science and Technology. Venue: Cincinnati, Ohio, USA. Date: 23rd to 25th June 2014.


Not recorded
Year(s) Of Engagement Activity 2014
 
Description Anisotropic Dielectrophoresis - Nematic Liquid Crystals 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Type Of Presentation paper presentation
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presenter: Carl Brown. Title: Anisotropic Dielectrophoresis - Nematic Liquid Crystals. Meeting: International Conference on Liquid Crystals (ILCC 2014). Venue: Trinity College Dublin, Ireland. Date: 29th June to 4th July 2014.


Not recorded
Year(s) Of Engagement Activity 2014
 
Description Attendance at The Mathematics of Liquid Crystals programme at INI in Cambridge 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Type Of Presentation paper presentation
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Research presentations delivered by Mottram on 24th January and 28th February 2013 during "The Mathematics of Liquid Crystals" programme at the Isaac Newton Institute for Mathematical Sciences in Cambridge.

Not recorded
Year(s) Of Engagement Activity 2013
 
Description British Applied Mathematics Colloquium 2013 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Type Of Presentation paper presentation
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Presenter: Lindsey Corson. Title: Liquid dielectrophoresis and wrinkling on the surface of a fluid layer. Meeting: BAMC 2013. Venue: University of Leeds. Date: 12th April 2013.



Not recorded
Year(s) Of Engagement Activity 2013
 
Description British Applied Mathematics Colloquium 2014 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Type Of Presentation paper presentation
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Presenter: Lindsey Corson. Title: Deformation of nearly hemispherical conducting drops by an electric field. Meeting: BAMC 2014. Venue: Cardiff University. Date: 30th April 2014.



Not recorded
Year(s) Of Engagement Activity 2014
 
Description British Applied Mathematics Colloquium 2015 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Presenter: Lindsey Corson. Title: Spontaneous wrinkling of a thin layer of nematic liquid crystal. Meeting: The 4th Joint British Mathematical Colloquium and British Applied Mathematics Colloquium (incorporating the 57th British Applied Mathematics Colloquium). Venue: Cambridge University. Dates: 30th March to 2nd April 2015.
Year(s) Of Engagement Activity 2015
 
Description British Liquid Crystal Society Conference 2015 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presenter: Antariksh Saxena. Title: Anisotropic dielectrophoresis - nematic liquid crystals. Meeting: The British Liquid Crystal Society Conference 2015 (BLCS 2015). Venue: Sheffield Hallam University, UK. Dates: 30th March to 1st April 2015.
Year(s) Of Engagement Activity 2015
 
Description Electric field induced deformation of sessile droplets 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation by Dr Lindsey Corson at British Council Researcher Links Workshop on Soft Matter: Analysis, Application and Challenges meeting held at National Institute for Mathematical Sciences (NIMS), Daejeon, South Korea on 18th to 21st March 2014.

This workshop comprised about 30 delegates from the UK and the Far East and was organised under the British Council Researchers Links scheme to open new avenues for interdisciplinary research connections between the United Kingdom and the Far East in mathematical modelling and condensed matter physics.

Not recorded
Year(s) Of Engagement Activity 2014
 
Description Electric field induced deformation of sessile droplets 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Type Of Presentation paper presentation
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presenter: Lindsey Corson. Title: Electric field induced deformation of sessile droplets. Meeting: 9th International Meeting on Electrowetting and Related Micro/Electrofluidic Science and Technology. Venue: Cincinnati, Ohio, USA. Date: 23rd to 25th June 2014.


Not recorded
Year(s) Of Engagement Activity 2014
 
Description From Carrot Juice to TVs: The Story of Liquid Crystals 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Multimedia publication titled "From Carrot Juice to TVs: The Story of Liquid Crystals".

Not recorded
Year(s) Of Engagement Activity 2014,2015,2016
URL https://www.youtube.com/watch?v=LWI3adR8r5U
 
Description Invited seminar: Bending, flexing, wrinkling and snapping of liquid drops 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Other audiences
Results and Impact Invited seminar at the University of Dundee: Bending, flexing, wrinkling and snapping of liquid drops
Year(s) Of Engagement Activity 2016
 
Description Leeds University, Applied Mathematics Seminar 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Presenter: Nigel Mottram. Title: Bending, flexing, wrinkling and snapping of liquid drops. Meeting: Applied Mathematics Seminar. Venue: Leeds University. Date: 27th April 2015.
Year(s) Of Engagement Activity 2015
 
Description Liquid dielectrophoresis and liquid crystal dielectrophoresis (L-DEP) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Invited talk by Carl Brown at I-CAMP'13 summer school on Liquid Crystals in Cambridge, UK, June 26 - July 6, 2013 (http://i-camp.colorado.edu/i-camp2013/).
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No recorded
Year(s) Of Engagement Activity 2013
URL http://i-camp.colorado.edu/i-camp2013/
 
Description Mathematical Sciences Research Seminar, University of Southampton 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Type Of Presentation paper presentation
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Presenter: Nigel Mottram. Title: Deformation of liquid drops and thin films under the influence of an electric field. Meeting: Mathematical Sciences Seminar. Venue: University of Southampton. Date: 6th May 2014.


Not recorded
Year(s) Of Engagement Activity 2014
 
Description Mathematics of Liquid Crystals 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Invited participant of Isaac Newton Institute programme, Mathematics of Liquid Crystals, Cambridge (Corson).

Not recorded
Year(s) Of Engagement Activity 2013
 
Description Mathematics of Liquid Crystals 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Invited participant in Mathematics of Liquid Crystals, Cambridge (Mottram).

Not recorded
Year(s) Of Engagement Activity 2013
 
Description Rheologists in Scotland II 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Postgraduate students
Results and Impact Presenter: Lindsey Corson. Title: Wrinkling of a layer of nematic liquid crystal. Meeting: Rheologists in Scotland II. Venue: University of Strathclyde, Glasgow. Date: 26th May 2015. Note: Joint winner of the prize for the best oral presentation.
Year(s) Of Engagement Activity 2015
 
Description Session chair for Session 12: Special Session on Dielectrophoresis 1 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Session chair for Session 12: Special Session on Dielectrophoresis 1 at 4th Advances in Microfluidics and Nanofluidics AMN 2013, South Bend, USA, 24-26 May 2013.

No recorded
Year(s) Of Engagement Activity 2013
 
Description Spreading and super spreading of droplets driven by liquid dielectrophoresis (L-DEP) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation at 4th Advances in Microfluidics and Nanofluidics AMN 2013, South Bend, USA, 24-26 May 2013.

Not recorded
Year(s) Of Engagement Activity 2013
 
Description Superspreading using interface localized liquid dielectrophoresis 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation of paper by Brown at Joint Smart and Green Interfaces Conference, COST MP1106 Annual Workshop and 5th International Conference on Heat Transfer and Fluid Flow in Microscale, Marseille, 22nd to 24th April 2014.

Not recorded
Year(s) Of Engagement Activity 2014
 
Description The Mathematics of Liquid Crystals Young Researchers' Meeting 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Type Of Presentation paper presentation
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Presenter: Lindsey Corson. Title: Liquid dielectrophoresis and wrinkling on the surface of a fluid layer. Meeting: The Mathematics of Liquid Crystals Young Researchers' Meeting. Venue: Isaac Newton Institute, University of Cambridge. Date: 21st May 2013.



Not recorded
Year(s) Of Engagement Activity 2013
 
Description University of Glasgow, Applied Mathematics Seminar 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Type Of Presentation paper presentation
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Presenter: Lindsey Corson. Title: Deformation of sessile drops and thin films by an electric field. Meeting: Applied Mathematics Seminar. Venue: University of Glasgow. Date: 23rd October 2014.



Not recorded
Year(s) Of Engagement Activity 2014