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Workpackages in detail
Workpackage 1
| Workpackage Title: Characterizing the substrates GaAs and SiOx coated GaAs | WP nr: 1 |
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| Starting date: month nr. 0 | Duration: 12 months | Total Effort (man/month): 18 |
| Partner involved | R&D Task/Activity of Partner | Effort (man/month): |
| REC2 | Performing FTIR and HREELS | 8 |
| HES3 | Performing XPS, and high energy electron energy loss spectroscopy | 10 |
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Objectives
Finding surface preparation methods in which a reproducible substrate is formed. Reproducibility will be determined by the electronic properties of the substrate and presence of contamination.
Description of work/tasks
Two types of surfaces will be investigated. Either bare GaAs (100 or 111) or GaAs coated with a thin layer (up to 80 nm) of SiO2. Chemical processing on gallium arsenide surfaces requires a rigorous control of the chemical state of the surface. So, a protocol of preparation methods for the substrate is needed to define their electronic characteristics and to establish the importance of the oxygen layer in determining these properties. In fact, substrates and particularly semiconducting surfaces of GaAs are usually covered by a thin native oxide thin film and very frequently present carbonaceous contamination. To obtain good conditions for chemisorption of the molecules onto the semiconducting surface, oxide and organic contamination must be removed. Substrates must then be treated before the molecular interaction, to eliminate any barrier blocking the interaction between the molecules and the semiconducting surface. Surfaces will be cleaned by chemical methods or by argon sputtering under vacuum conditions. The chemical state of the surface will be followed by surface elemental analysis as X-ray photo-electron spectroscopy (XPS). For atomically flat surfaces, an angle resolved analysis (ARXPS) allows the extraction of elemental concentration profiles in depth. Contribution of surface sensitive surface vibrational spectroscopy are also essential as they detect the chemical bonds present on the surface (HREELS). Chemical treatments realised under atmospheric conditions will be monitored by Fourier transform infrared spectroscopy (FTIRS) used in attenuated total reflection in multiple internal reflection (ATR-MIR).
Deliverables
D 1 Technical Report on the properties of substrates
Milestones and criteria
M .1 Defining the best substrate and its preparation method. Month 12.
Interaction with other workpackages
The results from this work-package are then the basis of what is done in WP2 and WP3.
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Workpackage 2
| Workpackage Title: Studying the binding of various functional groups to these substrates. | WP nr: 2 |
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| Starting date: month nr. 0 | Duration: 24 months | Total Effort (man/month): 52 |
| Partner involved | R&D Task/Activity of Partner | Effort (man/month): |
| REC1 | Leading. Develop the adsorption procedure for each functional group. | 12 |
| REC2 | Leading. Performing vibrational spectroscopy (HREELS and FTIR) studies on the samples. | 18 |
| HES3 | Performing high electron energy loss spectroscopy to study electronic excitations. | 8 |
| REC4 | Performing photoemission studies. | 14 |
| HES5 | Theoretical studies | 6 |
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Objectives
Procedures for adsorption of different binding groups will be developed and the hierarchy in binding strength for the different groups will be established.
Description of work/tasks
The chemical bonding between molecules and GaAs or SiOx coated GaAs surfaces will be investigated and the bond strength of each functional group will be determined. The adsorption of small molecules that contain functional groups adequate for chemisorption will be studied. The functional groups that will be investigated are amines, thiols, sulphides, carboxylates, and phosphates on GaAs surfaces and carboxylate, phosphate and silanes groups on SiOx surfaces.
The adsorption procedures will be developed by REC1. The samples will be delivered to the other partners for performing the analysis. HREELS and FTIRS will be used to study the presence of the adsorbed molecules and to identify bonds responsible for the chemisorption. Extending the energy loss domain, it is possible to detect electrons backscattered after producing electronic interactions in the adsorbed layer. In this case electronic states can be studied, and particularly interband transitions. The expertise of HES3 in studying electronic structure of adsorbed molecules will be particularly valuable in this part of our study.
The strength of the bonds as well as their effect on the electronic properties of the substrates (work function and band bending) will be determined. HES5 will perform theoretical studies on the nature of the bond to the surface.
Deliverables
D .2 Technical reports and meeting in which the results on the adsorption will be discussed.
Milestones and criteria
M .2 Finding the group that forms the strongest bond with a given substrate. Month 24.
Interaction with other workpackages
The results from this work-package are then the basis for the synthetic work done in WP3.
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Workpackage 3
| Workpackage Title: Synthesising porphyrins with the right binding groups. | WP nr: 3 |
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| Starting date: month nr. 0 | Duration: 18 months | Total Effort (man/month): 20 |
| Partner involved | R&D Task/Activity of Partner | Effort (man/month): |
| REC1 | Chemical analysis of the synthesis product. | 2 |
| IND6 | Synthesis. | 18 |
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Objectives
Obtaining the porphyrin species that both [a] binds strongly to the surface and also [b] binds strongly and selectively to nitric oxide.
Description of work/tasks
Several type of porphyrins molecules will be synthesised containing two functional groups, one that binds well to the substrate and another one that binds to the NO. Based on the results from WP2 the best surface binding group will be attached to the porphyrins. The binding to the NO is performed by a metal ion. Here the goal is to achieve high selectivity against binding to CO, O2 while keeping high affinity towards the NO. The binding constants of NO to hemes in the iron III state are of the order of 103-105 M-1 and the kinetics of NO dissociation is very fast. On the other hand, the binding constants of NO to iron II hemes are in the order of 1011 M-1 and the kinetics of NO dissociation is very slow. This difference should be taken into consideration when the porphyrin based sensor for NO is finalised. Additional sensitivity to NO may be obtained by simply changing the oxidation state of the porphyrin centre. The reversibility of the processes and thus the reusability of the device would be affected as well. An additional point is that iron III porphyrins do not react with CO. The iron II porphyrin is very reactive towards oxygen not only in solution but also in the solid state.
Another way by which metalloporphyrin sensitivity and selectivity towards NO can be enhanced is by changing the metal core. Cobalt, manganese, osmium, ruthenium porphyrins have been shown to bind NO reversibly as well. The synthesis of these metalloporphyrins from metal-free porphyrins is straight forward and well documented.
REC1 will perform the chemical analysis of the synthesized molecules using various analytical methods, IR, UV, NMR.
Deliverables
D 3. Technical Report on the synthesis of different porphyrins.
Milestones and criteria
M 3. The determination of the metal ion that binds selectively and with high affinity NO and that contain a surface-binding group as selected in WP2. Month 18.
Interaction with other workpackages
Information on the surface binding group is obtained from WP2. The results from this work-package are the basis of what is done in WP4.
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Workpackage 4
| Workpackage Title: Studying the interaction of adsorbed porphyrins with the substrates. | WP nr: 4 |
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| Starting date: month nr. 12 | Duration: 18 months | Total Effort (man/month): 56 |
| Partner involved | R&D Task/Activity of Partner | Effort (man/month): |
| REC1 | Developing adsorption procedure and photoelectron spectroscopy. | 10 |
| REC2 | Performing HREELS and ATR-MIR. | 14 |
| HES3 | Leading. Performing XPS and high electron energy loss spectroscopy (electronic excitation range). | 10 |
| REC4 | photoelectron velocity distribution studies. | 10 |
| HES5 | Theoretical studies. | 12 |
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Objectives
Optimising the adsorption method.
Description of work/tasks
The structure of the organic adlayer (the "nose" of the sensor) is strongly dependent on the substrate chemical properties, its morphology, on the nature of the chemical bonds between the substrate and the adsorbate, and on the intermolecular forces in the layer. REC1 will develop the methodology of adsorption of porphyrin on the substrates and the samples will be probed by various methods by the other partners involved in this workpackage. REC2 will use HREELS and ATR-MIR29, HES3 will apply XPS and high energy loss spectroscopy in the energy loss range corresponding to electronic transitions. In addition, photoelectron spectroscopy (by REC1) and photoelectron velocity (speed and angle) distribution studies (REC4) will be able to provide direct information on the change of the electrical potential of the substrate due to the adsorption and on the structure of the adsorbed layer, respectively. It also requires the development of theoretical methods (which will be conducted by HES5).
Adsorption kinetics of the porphyrin molecules onto the substrates can be followed in situ by ATR-MIR measurements. The adsorption will be optimised (in terms of time and homogeneity) by changing the solvent, temperature and the concentration of the adsorbent in the solution. XPS and HREELS studies can supplement the ATR-MIR results. Exploring the domain of electronic losses, also using HREELS, can give access to other parameters of the organic film such as the band gap width and the ionisation potential. AFM and STM studies will complete the investigation of the topology of the functionalized surfaces.
Deliverables
D .4 Meeting on the interaction of porphyrins with semiconductor substrates.
Milestones and criteria
M .4 Achieving well organized and characterised monolayer of porphyrin on the chosen substrate. Month 30.
Interaction with other workpackages
The results from this work-package are then the basis of what is done in WP3 and WP5.
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Workpackage 5
| Workpackage Title: Studying the nitric oxide interaction with functionalized surfaces. | WP nr: 5 |
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| Starting date: month nr. 18 | Duration: 18 months | Total Effort (man/month): 46 |
| Partner involved | R&D Task/Activity of Partner | Effort (man/month): |
| REC4 | Leading. Adsorption of NO on the porphyrin coated substrate. | 14 |
| REC2 | Performing HREELS and ATR-MIR. | 12 |
| HES3 | Performing XPS and high electron energy loss spectroscopy (electronic excitation energy losses range). | 8 |
| HES5 | Theoretical studies. | 12 |
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Objectives
Defining the recognition of NO by the functionalized surface and the change in the electronic properties of semiconductor substrate. We will identify the porphyrin/substrate system that is mostly affected (in terms of electronic properties) by the adsorption of NO.
Description of work/tasks
NO will be adsorbed or scattered on the substrates functionalized by different porphyrins. The scattering experiments will be performed by REC4. Spectroscopical methods (as described above) will serve for obtaining structural information on the complex. The modification of the photoelectron spectrum either in energy or in spatial distribution will be monitored for both the semiconductor substrate and the adsorbed or scattered NO molecules. These changes will be correlated with the observed modulation in the current through the MOCSER as will be investigated in WP6.
Deliverables
D .5 Report on the interaction of NO with semiconductor substrate coated with well characterised and reproducible monolayer of porphyrin.
Milestones and criteria
M .5 Obtaining a porphyrin coated substrate that binds NO with high selectivity and with high affinity. The adsorbed NO must affect the electronic properties of the substrate (work function and band bending). Month 36.
Interaction with other workpackages
The results from this work-package are then the basis of what is done in WP3 and WP6.
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Workpackage 6
| Workpackage Title: Investigating the sensitivity and selectivity of the hybrid device. | WP nr: 6 |
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| Starting date: month nr. 18 | Duration: 18 months | Total Effort (man/month): 20 |
| Partner involved | R&D Task/Activity of Partner | Effort (man/month): |
| REC1 | Leading. Studying the sensitivity of the MOCSER towards NO. | 8 |
| HES5 | Theoretical studies. | 6 |
| IND6 | Producing the MOCSER. | 6 |
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Objectives
Determining the sensitivity and selectivity of the hybrid device towards NO.
Description of work/tasks
Electronic measurements will be performed on the MOCSER coated with the porphyrin in order to establish the effect of the porphyrin itself on the current through the MOCSER. Following this, the device will be exposed to NO and the change in the current through the device will be monitored for various concentrations of NO in air. In addition, NO will be mixed with other gases (oxygen, CO) in order to determine the selectivity of the response of the MOCSER to nitric oxide. Theoretical modelling will be performed to relate the change in the current through the device to the adsorption of NO.
Deliverables
D .6 Demonstrating the ability of the hybrid device to sense NO).
Milestones and criteria
M .6 Demonstration of the device to detect 40 pM of NO with a selectivity of better than 105 versus CO and oxygen. Month 36.
Interaction with other workpackages
The results from this work-package are then the basis of what is done in WP7.
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Workpackage 7
| Workpackage Title: Manufacturing of a technological prototype. | WP nr: 7 |
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| Starting date: month nr. 24 | Duration: 12 months | Total Effort (man/month): 16 |
| Partner involved | R&D Task/Activity of Partner | Effort (man/month): |
| REC1 | Calibration of the prototype. | 2 |
| REC2 | Measuring the selectivity of the prototype. | 2 |
| IND6 | Producing the Prototype. | 12 |
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Objectives
Producing a prototype for measuring nitric oxide in exhaled air.
Description of work/tasks
Based on the results obtained in the former work-packages, the chosen molecule will be adsorbed on the surface of the GaAs based device and the sensitivity and selectivity towards nitric oxide will be determined. Following these studies the sensor will be packaged so that it would be possible to test it in field experiments. The prototype will be calibrated with precalibrated gas mixtures.
The Product: Hand held asthma meter.
The proposed product will be composed of two units: electronics reusable unit and a mouth piece sensor disposable unit. The electronic unit will be composed of LCD to indicate the level of exhaled NO as well as an alarm. The mouth piece disposable unit will contain the NO sensor.
Deliverables
Prototype (D7).
Milestones and criteria
Demonstration of the ability of the prototype to detect variations of 40 pM of NO with a selectivity of better than 105 versus CO and oxygen in exhaled air.
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Workpackage 8
| Workpackage Title: Management. | WP nr: 8 |
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| Starting date: month nr. 0 | Duration: 36 months | Total Effort (man/month): 15 |
| Partner involved | R&D Task/Activity of Partner | Effort (man/month): |
| REC1 | Co-ordinator. | 9 |
| REC2 | Member in the stirring committee. | - |
| IND6 | Industrial exploitation. | 6 |
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Objectives
Managing the consortium and exploitation of the technical outcome.
Description of work/tasks
REC1 will be the co-ordinator of the project while IND6 will develop the industrial exploitation and will be responsible for all the connections with other industries. REC2 will be a member of the steering committee and will help in monitoring the achievements according to the list of Milestones.
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