Date:

2007-2010

Theme:

Microfluidics and Lab-on-a-chip

Funding:

Department

Dielectrophoresis (DEP), a phenomenon through which non-uniform electric field exerts force on a dielectric particle immersed in a dielectric medium, is one of the most widely-used techniques for manipulating and characterising biological particles in a lab-on-a-chip device. Inaccurate calculation of the DEP force would lead to incorrect modelling of the device or false determination of particle properties. Most, if not all, models in current literature are based on the so-called "dipolar approximation" for making calculation of the DEP force. This approximation accounts only for the first-order force term and ignores all higher-order terms. Theory predicts this approximation to work well only as long as particle dimensions are much smaller than those of the electrode geometry through which the electric field is applied. When the field magnitude varies significantly across the dimensions of the particle, which is a very likely occurrence as electrode geometries shrink in dimensions towards micro-electrode geometries, higher-order force terms are expected to gain increased significance. The same principle applies to torques of electric origin experienced by dielectric particles in lab-on-a-chip devices through the phenomena of electro-rotation (ROT) and electro-orientation (EO).

The preliminary aim of this project is to identify situations where higher-order forces are expected to contribute to a considerable extent to the total DEP force. To accomplish this goal, separate calculations have been made, numerically, of the first three terms of the DEP force, based on the "effective moment method", and of the total DEP force, based on an integration of the Maxwell stress tensor, for particles of different shapes and dimensions subjected to electric fields of varied extents of non-uniformity. Through a comparison of the two sets of results it has been verified that when particle dimensions, be the particles spherical or not, become comparable to a length scale of field non-uniformity, higher-order force terms become increasingly significant such that in some cases they exceed the first-order force term thereby proving the dipolar approximation wrong.

Once instances where higher-order force and torque terms become significant are discovered, the ultimate goal of this project comes into play: to realize an application where higher-order forces and/or torques could dictate particle behaviour in a way that cannot be achieved using a force/torque whose higher-order terms are negligible. One goal in mind is to achieve particle stabilisation through the exertion of higher-order electro-orientational (EO) torques.

Primary investigators

• hn07r
• Nicolas Green

Associated research group

• Nano Research Group

Date:

2007-2010

Theme:

Microfluidics and Lab-on-a-chip

Funding:

Department

Dielectrophoresis (DEP), a phenomenon through which non-uniform electric field exerts force on a dielectric particle immersed in a dielectric medium, is one of the most widely-used techniques for manipulating and characterising biological particles in a lab-on-a-chip device. Inaccurate calculation of the DEP force would lead to incorrect modelling of the device or false determination of particle properties. Most, if not all, models in current literature are based on the so-called "dipolar approximation" for making calculation of the DEP force. This approximation accounts only for the first-order force term and ignores all higher-order terms. Theory predicts this approximation to work well only as long as particle dimensions are comparable to those of the electrode geometry through which the electric field is applied. When the field magnitude varies significantly across the dimensions of the particle, which is a very likely occurrence as electrode geometries shrink in dimensions towards micro-electrode geometries, higher-order force terms are expected to gain increased significance. The same principle applies to torques of electric origin experienced by dielectric particles in lab-on-a-chip device through the phenomena of electro-rotation (ROT) and electro-orientation (EO). The preliminary aim of this project is to identify situations where higher-order forces are expected to contribute to a considerable extent to the total DEP force. To accomplish this goal, separate calculations have been made, numerically, of the first three terms of the DEP force, based on the "effective moment method", and of the total DEP force, based on an integration of the Maxwell stress tensor, for particles of different shapes and dimensions subjected to electric fields of varied extents of non-uniformity. Through a comparison of the two sets of results it has been verified that there when particle dimensions, be the particles spherical or not, become comparable to a length scale of field non-uniformity, higher-order force terms become increasingly significant such that in some cases they exceed the first-order force term thereby proving the dipolar approximation wrong. Once instances where higher-order force and torque terms are significant are discovered, the ultimate goal of this project comes into play: to realize an application where higher-order forces and/or torques could dictate particle behaviour in a way that cannot be achieved using a force/torque whose higher-order terms are negligible. One goal in mind is to achieve particle stabilisation through the exertion of higher-order electro-orientational (EO) torques.

Primary investigators

• hn07r
• Nicolas Green

Associated research group

• Nano Research Group

Date:

2007-2010

Theme:

Microfluidics and Lab-on-a-chip

Funding:

Department

Dielectrophoresis (DEP), a phenomenon through which non-uniform electric field exerts force on a dielectric particle immersed in a dielectric medium, is one of the most widely-used techniques for manipulating and characterising biological particles in a lab-on-a-chip device. Inaccurate calculation of the DEP force would lead to incorrect modelling of the device or false determination of particle properties. Most, if not all, models in current literature are based on the so-called "dipolar approximation" for making calculation of the DEP force. This approximation accounts only for the first-order force term and ignores all higher-order terms. Theory predicts this approximation to work well only as long as particle dimensions are comparable to those of the electrode geometry through which the electric field is applied. When the field magnitude varies significantly across the dimensions of the particle, which is a very likely occurrence as electrode geometries shrink in dimensions towards micro-electrode geometries, higher-order force terms are expected to gain increased significance. The same principle applies to torques of electric origin experienced by dielectric particles in lab-on-a-chip device through the phenomena of electro-rotation (ROT) and electro-orientation (EO).

The preliminary aim of this project is to identify situations where higher-order forces are expected to contribute to a considerable extent to the total DEP force. To accomplish this goal, separate calculations have been made, numerically, of the first three terms of the DEP force, based on the "effective moment method", and of the total DEP force, based on an integration of the Maxwell stress tensor, for particles of different shapes and dimensions subjected to electric fields of varied extents of non-uniformity. Through a comparison of the two sets of results it has been verified that there when particle dimensions, be the particles spherical or not, become comparable to a length scale of field non-uniformity, higher-order force terms become increasingly significant such that in some cases they exceed the first-order force term thereby proving the dipolar approximation wrong.

Once instances where higher-order force and torque terms are significant are discovered, the ultimate goal of this project comes into play: to realize an application where higher-order forces and/or torques could dictate particle behaviour in a way that cannot be achieved using a force/torque whose higher-order terms are negligible. One goal in mind is to achieve particle stabilisation through the exertion of higher-order electro-orientational (EO) torques.

Primary investigators

• hn07r
• Nicolas Green

Associated research group

• Nano Research Group

Date:

2008-2011

Theme:

Microfluidics and Lab-on-a-chip

Funding:

EPSRC

My main research area in interest on RMST project is ‘Micro-fluidic and Lab on a chip Technology’. I am concentrating on the research for the development of technologies involves fabrication of micro-structure (micro-electrodes) and micro-fluidic polymeric devices. In addition, I am also concentrating on technologies for hot embossing process (HE) on polymers (e.g. COC, COP, PMMA etc) for creating micro-fluid structure and aligned bonding techniques to seal micro-devices.High aspect ratio silicon (Si) mould master is fabricated with micro-fluidic structure using deep reactive ion etched technique (DRIE) to create Ni master using electro-form technique to emboss microfluidic structure on polemers.

Figure 1 shows a Si mould master with micro-fluidic structure. This mould is used for Ni electro-plating. Figure 2 shows a embossed micro-fluidic channel on zeonox 690R COC (Tg 136°C )using Ni stamp.

Primary investigators

• Prof Hywel Morgan
• Dr Matt Mowlem

Secondary investigator

• Dr Shahanara Banu

Partner

• •National Oceanography Centre (Sensors group)

Associated research groups

• Nano Research Group
• Southampton Nanofabrication Centre

Date:

2001-2001

Theme:

Microfluidics and Lab-on-a-chip

Funding:

EPSRC

ss

Primary investigator

• Prof hywel Morgan

Partner

• National Oceanography Centre (Sensors group)

Associated research group

• Nano Research Group

Themes:

Nanoelectronics, MEMs and NEMs, Quantum Electronics and Spintronics

Funding:

CONACyT, Mexico

As one of promising candidates for a scalable non-volatile memory, we proposed a new suspended-gate silicon nanodot memory (SGSNM) by co-integrating nanoelectromechanical systems (NEMS) and conventional MOSFETs. The SGSNM consists of a MOSFET as readout, silicon nanodots (SiNDs) as a floating gate (FG), and a movable suspended gate (SG) which is isolated from the FG by an air gap and a thin oxide layer. The advantages of the SGSNM cell over the typical flash memory include high speed programming/erasing operations, virtually no gate leakage current and therefore a serious non-volatility, thanks to the presence of the air gap except for the program/erase processes. For programming the SGSNM cell, a negative gate voltage is applied, and the SG is pulled-in on the FG layer, resulting in electron injection from the SG into the FG. For erasing the cell, a positive voltage is applied, and the stored electrons are extracted from the FG.

Primary investigators

• magr07r
• hm2
• Yoshishige Tsuchiya

Partners

• Hitachi Central Research Laboratory
• Tokyo Institute of Technology

Associated research groups

• Nano Research Group
• Southampton Nanofabrication Centre

Date:

2009-2011

Theme:

Nanoelectronics

Carbon Nanotubes have generated a great deal of interest due to their extraordinary mechanical, thermal and electronic properties and they are being researched as a potential replacement for Si for future electronic devices. However, there are significant problems in nanotube growth, positioning and contacting that remain to be solved.

Previous work involving electrodeposition of Ni on Si has shown that the characteristics of the schottky barrier formed are superior to those formed by evaporation. Palladium has been shown to form very good contacts to carbon nanotubes. By electrodepositing PdNi alloys, it may be possible to get ferromagnetic contacts to nanotubes with superior contacting properties compared to current methods.

This project will investigate the use of electrodeposited PdNi metallic contacts to carbon nanotubes and investigate if this method results in the formation of better contacts as compared to evaporated alloys. The presence of Ni in the alloys will also allow a study magnetoresistance effects in nanotubes with electrodeposited ferromagnetic contacts.

Primary investigator

• aru07r

Associated research groups

• Nano Research Group
• Southampton Nanofabrication Centre

Date:

2008-2012

The project is aimed to develop micro-fabrication technology including; Fabrication of metal electrodes using various technologies i.e., Ion Beam Mill, lift off method etc. Also the project involves with the development for the fabrication of micro-fluidic structure using dry film resist photo resist and SU8 negative photoresist. The project is also concentrating on hot embossing (HE)method using EVG 520 boder for the fabrication of fluidic structure on different polymers such as COC. COP, PMMA and others using Ni, Si, and soft HE stamps. Also the sealing and aligned bonding of micro-fluidic structure is being carried out using thermal bonding and UV glue bonding technology by using EVG 620 mask aligner and EVG bonder.

Primary investigators

• Prof Hywel Morgan
• Dr Matt Mowlem

Associated research group

• Nano Research Group

Date:

2008-2012

Themes:

Nanoelectronics, MEMs and NEMs, Bionanotechnology and Biosensors

Funding:

EUFP7

Precise detection of different species of chemical or biomolecules is fundamental to a vast variety of applications including medical science and environmental studies. Typically, a sensor is exposed to a sample to spot the possible existence of target molecules. The sample can be a gas or liquid possibly containing the target and even some other species. So, it may be required to make the sensor sensitive only to the proposed target molecules by functionalisation. Besides, achieving higher sensitivities is always appreciated. Some applications depend tightly on the time needed for the detection. Therefore, detection speed can be considered as a constraint. This factor can be affected by the type and number of stages involved in the detection procedure.