Name:

Dr. Martina O'Toole 

 

 

Contact details

CLARITY: Centre for Sensor Web Technologies
National Centre for Sensor Research

School of Chemical Sciences 
Dublin City University
Glasnevin
Dublin 9
Ireland

Tel (Lab): +353 1 7007604

Tel (Office): +353 1 7007926

Fax: +353 1 7007995

 

Qualifications

B.Sc., Dublin City University, Analytical Science, 2003.

Ph.D., Dublin City University, Chemistry, Thesis Title: Novel Integrated Paired Emitter-Detector Diode Flow Analysis System, 2007.

Project Summary

My research at the National Centre of Sensor Research has focused on the development of a miniaturised Paired Emitter-Detector Diode (PEDD) optical detector for colorimetric analysis based on the concept of an LED serving as both the light source and detector as developed within the research group. This research was funded by Science Foundation Ireland (SFI). This novel optical sensor employs two LEDs, operating one as a light source and the other as a light detector. The emitter LED is forward biased and the detector reverse biased. A simple timer circuit measures the time taken for the photocurrent generated by the emitter LED to discharge the detector LED from 5 V (logic 1) to 1.7 V (logic 0). The PEDD sensor is very versatile and can be configured in a variety of ways to measure absorbance or reflectance as shown in Figure 1.

 

 

Figure 1: Schematic of various PEDD configurations; (1) Sample picks up reagent – direct transmission, (2) Immobilize reagent onto surface of LED source/detector, (3) Immobilize dye directly onto fabric and (4) Back-end reflectance or evanescent wave sensing of immobilised dye

 

The PEDD has been applied as an inexpensive detector in a flow-injection system for determining low concentration levels of phosphate employing the malachite green spectrophotometric method. The novel flow detector employed within this manifold is a highly sensitive, low cost, miniaturized light emitting diode (LED) based flow detector, which achieved an improved LOD in comparison to a LED-photdiode sensor. The PEDD has also been applied as a photometric detector in HPLC. Separation of transition metal ions, manganese (II) and cobalt (II) were carried out using a Nucleosil 100-7 (functionalised with IDA groups) column (Figure 2).

 

 

Figure 2: A comparison of the chromatograms obtained for the detection of 5 mM Mn (II) and Co (II) PAR complexes using the spectrophotometric detector (A) and the PEDD flow device (B).

 

The PEDD was calibrated using Mn (II) and Co (II) PAR complexes providing a linear response. Higher sensitivity and improved precision were obtained from the PEDD compared to the commercially available UV-vis variable wavelength detector. The results obtained using the integrated PEDD flow analysis cell have demonstrated that this simple low cost, low power device can be used as a photometric detector in HPLC. This optical sensor has the potential for very broad analytical applications, given that it offers high sensitivity and precision with excellent signal-to-noise characteristics. The PEDD flow cell is therefore ideal for detection of multiple analytes when operated in conjunction with a separation technique.

A simple PEDD detector cannot replace the existing variable wavelength detector because of the limited bandwidth a single LED can cover, however, a more sophisticated PEDD device with multiple LED sources covering a wider range of wavelengths could make this possible. For specific applications where an appropriate operation wavelength can be selected for the analytes a single PEDD flow detector is ideal and preferable to a more complex multi-source detector. This small flow detector when coupled with a miniature low pressure separation column, such as the one used in this work, and a pressure/pumping unit, such as a small gas cylinder, could form a complete miniature HPLC system suitable for rapid small sample analysis.  Apart from working as a small bench top analytical device, such a system may also be developed as a field deployable autonomous monitoring device.

 

A distinct advantage of using the PEDD optical sensor in comparison with widely used LED-photodiode system is that the LED–LED combination is less expensive in both the cost of components (35 US cents per sensor) and the cost of the signal transduction circuitry. The measuring technique employed by the PEDD device does not require a relatively expensive A/D converter as the output seen by the microprocessor is a direct pulse-duration-modulated signal. Additional advantages to the PEDD device is the size, low power consumption (can operate in microwatts range), can detect low absolute light levels (ca. 0.0001 lx), responds to a broad spectral range (250 to >900 nm) and can achieve good S/N ratio. 

 

Publications

 

 

 

Journal Paper:

 

1.  Martina O’Toole, King Tong Lau, Dermot Diamond, Photometric detection in flow analysis systems using integrated PEDDs, Talanta, Volume 66, Issue 5, 15 June 2005, Pages 1340-1344.  

 

2.   King Tong Lau, Susan Baldwin, Martina O'Toole, Roderick Shepherd, William J. Yerazunis, Shinichi Izuo, Satoshi Ueyama and Dermot Diamond, A Low-Cost Optical Sensing Device based on Paired Emitter-Detector LEDs, Analytica Chimica Acta, Volume 557, Issues 1-2, 31 January 2006, Pages 111-116.  

 

3.   Martina O’Toole, King Tong Lau, Benjamin Shazmann, Roderick Shepherd, Pavel N. Nesterenko, Brett Paull and Dermot Diamond, Novel Integrated Paired Emitter Detector Diode as a Miniaturized Photometric Detector in HPLC, The Analyst, Volume 131, Issue 8, 20 June 2006, Pages 938-943. 

 

 

4.   Leon Barron, Pavel N. Nesterenko, Dermot Diamond, Martina O'Toole, King Tong Lau and Brett Paull, Low Pressure Ion Chromatography with a Low Cost Paired Emitter-Detector Diode Based Detector for the Determination of Alkaline Earth Metals in Water Samples, Analytica Chimica Acta, Volume 577, Issue 1, 1 September 2006, Pages 32-37. 

 

5.   Martina O’Toole, King Tong Lau, Roderick Shepherd, Conor Slater and Dermot Diamond, Determination of Phosphate using a Highly Sensitive Paired Emitter-Detector Diode Photometric Detector, Analytica Chimica Acta, Volume 597, Issue 2, 29 May 2007, Pages 290-294. 

 

6.     Martina O’Toole, Roderick Shepherd, King Tong Lau and Dermot Diamond, Detection of nitrite by flow injection analysis using a novel paired emitter-detector diode (PEDD) as a photometric detector, SPIE (Advanced Environmental, Chemical, and Biological Sensing Technologies V), Vol. 6755, 25 September 2007, Pages 67550P/1-67550P/10. 

 

7.   Martina O'Toole and Dermot Diamond, Absorbance Based Light Emitting Diode Optical Sensors and Sensing Devices, Sensors, Volume 8, Issue 4, 31 March 2008, Pages 2453-2479. 

 

8.   Sonia Ramírez-García, María del Mar Baeza, Martina O’Toole, Yanzhe Wu, James Lalor, Gordon G. Wallace and Dermot Diamond, Towards the development of a fully integrated polymeric microfluidic platform for environmental analysis, Talanta, Volume 77, Issue 2, 4 April 2008, Pages 463-467.  

 

9.   Leon Barron, Martina O'Toole, Brett Paull, Pavel Nesterenko and Dermot Diamond, Separation of transition metals on a poly-iminodiacetic acid grafted poymeric resin column with post-column reaction detection utilising a paired emitter detector diode system, Journal of Chromatography A, Volume 1213, Issue 1, 19 August 2008, Pages 31-36. 

 

10. Martina O’Toole, Leon Barron, Roderick Shepherd, Pavel N. Nesterenko, Brett Paull and Dermot Diamond, Paired Emitter-Detector Diode Detection with Dual Wavelength Monitoring for Enhanced Sensitivity to Transition Metals in Ion Chromatography with Post-Column Reaction, The Analyst, Volume 134, Issue 1, 2 October 2008, Pages 124-130.

 

11. Martina O’Toole, Roderick Shepherd, Gordon G. Wallace and Dermot Diamond, Inkjet Printed LED based pH Chemical Sensor for Gas Sensing, Analytica Chimica Acta, Volume 652, Issue 1-2, 6 July 2009, Pages 308-314.

 

12.Tanja Radu, John Cleary, Martina O’Toole, Aleksandar Radu and Dermot Diamond, Analytical Devices for Autonomous Monitoring of the Environment, 2004-RS-AIC-M4 STRIVE report, EPA Ireland (2009) Accepted.

 

Magazine Article:

 

1.   Leon Barron, Martina O'Toole, Brett Paull, Pavel Nesterenko and Dermot Diamond, Metal Catches The Light, SeparationsNOW.com - Detectors, September 2008

 

Book Chapter:

 

1.   Martina O'Toole, Robert Byrne and Dermot Diamond, Novel Applications of Absorbance Based Light Emitting Diode Optical Devices, Handbook of Light Emitting and Schottky Diode Research, Nova Science Publishers, Inc., June 2008, Accepted.

 

Poster Presentation:

 

1.   Martina O'Toole, King Tong Lau and Dermot Diamond, Chemical Sensing using Paired Emitter-Detector Diode Devices in Transmission Mode, 56^th Irish Universities Chemistry Research Colloquium (UCRC), Limerick, Ireland, June 2004 

 

2.   Martina O'Toole, King Tong Lau and Dermot Diamond, Paired Emitter Detector Diode (PEDD) Based Platform for Colorimetric Detection in Flow Analysis, Analytical Research Forum, University of Central Lancashire, Preston, England, July 2004  

 

3.   Martina O'Toole, King Tong Lau and Dermot Diamond, (Paired Emitter Detector Diode (PEDD) Based Platform for Colorimetric Detection in Flow Analysis), 3rd Biennial Conference on Analytical Sciences in Ireland, Cork University, Cork, Ireland, September 2004 (Awarded Best Poster)

 

4.   Leon Barron, Martina O'Toole, King Tong Lau, Dermot Diamond, Pavel Nesterenko and Brett Paull Development of a low pressure ion chromatography for the determination of alkaline earth metals in environmental samples, 4th Biennial Conference on Analytical Sciences in Ireland, D.I.T., Dublin, Ireland, April 2006 (Awarded Best Poster)

 

5.   Leon Barron, Martina O'Toole, King Tong Lau, Dermot Diamond, Pavel Nesterenko, Brett Paull, Low pressure chromatography of anions and cations in environmental water samples, HPLC 2006, San Francisco, CA, USA, June, 2006 

 

6.   Brett Paull, Martina O'Toole, Leon Barron, King Tong Lau and Dermot Diamond, Rapid ion Chromatography of Transition Metals on a Short Polymeric Grafted Polyiminodiacetic Acid Column with Post-column Reaction Detection with a Paired Emitter-Detector Diode (PEDD) Detector, 19th International Ion Chromatography Symposium, Pittsburgh, Pennsylvania, USA, September 2006 (Nominated for Best Poster)

 

7.   Martina O'Toole, King Tong Lau, Roderick Shepherd and Dermot Diamond, Detection of Nitrite by Flow Injection Analysis Using a Novel Paired Emitter-Detector Diode (PEDD) as a Photometric Detector, Pittcon 2007, Chicago, USA, March 2007

 

8.   Martina O’Toole, Leon Barron, Roderick Shepherd, Pavel N. Nesterenko, Brett Paull and Dermot Diamond, Paired emitter-detector diode detection with dual wavelength monitoring for enhanced sensitivity to transition metals in ion chromatography with post-column reaction, 5th Biennial Conference on Analytical Sciences in Ireland, W.I.T., Waterford, Ireland, May 2008 

 

9.   Christine Bracken, Aleksandar Radu, Martina O’Toole, Mercedes Vasquez and Dermot Diamond, Light-controlled partitioning of spiropyran between polar and non-polar solvents, 3rd International Conference on Smart Materials, Structures and Systems, Sicily, Italy, June 2008 (Selected as Hot Poster)

 

10. Martina O’Toole, Leon Barron, Roderick Shepherd, Pavel N. Nesterenko, Brett Paull and Dermot Diamond, Paired emitter-detector diode detection with dual wavelength monitoring for enhanced sensitivity to transition metals in ion chromatography with post-column reaction, 20th International  Ion Chromatography Symposium, Portland, Oregon USA, September 2008

 

11. Martina O'Toole and Dermot Diamond, Integrated LED Based Flow Analysis Device, 4th Annual Lab on a Chip European Congress 2010, Dublin, Ireland, May 2010

 

  

Oral Presentation: 

 

1.   Martina O’Toole, King-Tong Lau, Benjamin Shazmann, Roderick Shepherd, Pavel N. Nesterenko, Brett Paull and Dermot Diamond, Paired Emitter Detector Diode (PEDD) as a Miniaturized Photometric Detector in LC systems, 58th Irish Universities Chemistry Research Colloquium, Limerick NUI, Galway, June 2006 

 

2.   Martina O’Toole, King-Tong Lau, Benjamin Shazmann, Roderick Shepherd, Pavel N. Nesterenko, Brett Paull and Dermot Diamond, Novel Integrated PEDD as a Miniaturized Photometric Detector in HPLC, Analytical Research Forum 06, Cork University, July 2006 

 

3.   Martina O’Toole, King Tong Lau, Roderick Shepherd and Dermot Diamond, Novel Integrated PEDD as a Photometric Detector in Flow Analysis Systems, X international conference of flow analysis, Porto, Portugal, September 2006 

 

4.   Martina O’Toole, Leon Barron, Roderick Shepherd, King Tong Lau,  Pavel N. Nesterenko, Brett Paull and Dermot Diamond, Paired emitter-detector diode (PEDD) dual wavelength monitoring procedure for sensitivity improvements in ion chromatography determinations employing a post-column spectrophotometric reaction, 19th Annual International  Ion Chromatography Symposium, Pittsburgh, Pennsylvania, USA, September 2006 

 

5.   Sonia Ramírez-García, María del Mar Baeza, Martina O’Toole, Yanzhe Wu, James Lalor, Gordon G. Wallace and Dermot Diamond, (Fully integrated polymeric microfluidic platform for environmental analysis), ICFIA 2007, Berlin, Germany, September 2007 

 

6.   Martina O’Toole, Roderick Shepherd, King Tong Lau and Dermot Diamond, (Detection of nitrite by flow injection analysis using a novel paired emitter-detector diode (PEDD) as a photometric detector), SPIE Optics East 2007, Boston, USA, September 2007

 

7.   Leon Barron, Martina O'Toole, Brett Paull, Pavel Nesterenko and Dermot Diamond, Separation of transition metals on a poly-iminodiacetic acid grafted poymeric resin column with post-column reaction detection utilising a paired emitter detector diode system, 20th International  Ion Chromatography Symposium, Portland, Oregon USA, September 2008.   

 

8.  Martina O’Toole, Leon Barron, Brett Paull and Dermot Diamond, A highly sensitive LED based miniaturised photometric detector applied to liquid chromatography, 21st Annual International  Ion Chromatography Symposium, Dublin, Ireland, September 2009 

 

Further Information

Research Collaborations:

 

 

2005 - Mitsubishi Electric Research Laboratories, Boston, MA, USA

I completed a 2 month internship at Mitsubishi Electric Research Laboratories (MERL) in June 2005. My research (Supervisor Dr. William Yerazunis) included the design and fabrication of a microfluidic fuel cell pump (patent approved).

 

 

2008 - University of Wollongong, Wollongong, Australia

I spent 2 months working in the Intelligent Polymer Research Institute (IPRI) facility at the University of Wollongong (UOW) in collaboration with Professor Gordon G. Wallace and Dr. Roderick Shepherd. My research included the development of colorimetric pH gas sensors. The gas sensors were fabricated by inkjet printing the sensor formulation directly onto an LED optical detector (PEDD). The deposition method of inkjet printing demonstrated significantly improved reproducibility in terms of film thickness and response magnitude than that achieved employing drop casting.

 

Awards:

2004, Award For Best Poster, 3rd Biennial Conference on Analytical sciences in Ireland, University College Cork, Ireland

 

2006, Student Travel Bursary, Royal Society of Chemistry, Analytical Research Forum, University College Cork, Ireland

 

2006, Nominated for Best Poster, 19th Annual International Ion Chromatography Symposium, Pittsburgh, Pennsylvania, USA

 

2006, Overseas Conference Travel Grant, Royal Society of Chemistry, 19th Annual International Ion Chromatography Symposium, Pittsburgh, Pennsylvania, USA

 

2006, Award For Best Poster, 4th Biennial Conference on Analytical sciences in Ireland, Dublin Institute of Technology, Ireland

 

2008, Selected as Hot Poster, 3rd International Conference on Smart Materials, Structures and Systems, Sicily, Italy