Most people did not even know what melatonin was when we told them about our project, so how should they know about correlated diseases?
Our human practices goal was to learn more about it and to share our newly gained knowledge with the world.
We also met other science enthusiasts to spread the word of synthetic biology and the importance of science in society.
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Integrated Human Practices
Without the advice of helpful experts, our project would not have taken shape the way it did.
In this section, the influences of other scientists on the development of Melasense are retraced.
Please click on one of the buttons to read the respective article.
European Drug Approval
Interview with Leon Bongers and Tania Mattila about melatonin as medication and its approval.
We talked with Leon Bongers and Tania Mattila from the Dutch Medicines Evaluation Board (MEB) about the process of approval
for Melatonin in the Netherlands and in the European Union.
We learned that the availability of melatonin could only change through pressure of pharmaceutical companies. They also dicussed with us the chances and risks of melatonin supplementation.
We were very surprised that there is such a strict regulation of the availability of melatonin in our country. Circadin is a prescription medication containing melatonin, which has been approved in the whole European Union from the age of 55.
In Germany, in contrast to other countries, melatonin products as dietary supplements are strictly regulated, while in our neighbour country the Netherlands, they are freely available.
We learned from the IGJ (Inspectie Gezondheidszorg en Jeugd), the responsible institution for the approval of dietary supplements in the Netherlands, that a melatonin-containing product is only considered a medicine if it contains at least 0,3 mg of melatonin and claims to cure a disease.
Our team member Katrin interviewed clinical assessor Tania Mattila and Leon Bongers, the Senior Regulatory Project Leader of Pharmacotherapeutic Group I, both from the MEB. Leon Bongers is responsible for the approval of melatonin as a medicine in the Netherlands.
He and Mrs. Mattila explained to us that in the Netherlands it is assumed that the population only takes melatonin after consultation with a doctor and that the number of studies on melatonin for short-term use is sufficient since there are no worrying side effects when taken correctly, but there are not enough studies on melatonin for a longer period. In addition, we learned that it is apparently not enough to raise general awareness to the positive effects of melatonin in the society.
An amendment to the law in Germany could only be achieved by pressure from the pharmaceutical industry. Then, melatonin could be available in Germany for humans under fifty-five, too.
To learn more about the process of drug approval in the EU and to inform yourself about the risks and when it is reasonable to supplement melatonin, please read our interview below.
Katrin: Have you heard about the correlation between Melatonin and neurological disorders, like depression, Parkinson's,
Alzheimer's disease and fibromyalgia?
Leon Bongers: We know that a melatonin disbalance can play a role in many disorders like the ones that you mentioned. But I think there is too little data available concerning the effects on giving melatonin to correct the imbalance in this disorders, there haven't been specific claims for melatonin disorders. So it hasn't played a part in the authorization application that we have had so far.
Katrin: We think it would be interesting to know more about the process of the medical authorization in the CBG and also how you work together with the EU.
Leon Bongers: The MEB and most regulatory authorities in Europe only work by paper. The tests are being done by a pharmaceutical company that often relies completely on papers and literature. A company submits to us a dossier with detail on the manufacturing, indication, and safety of the product. Then the application is assessed by different specialized assessment groups, for example, clinical assessors like Taina, but there is also a non-clinical assessment. The assessors make reports which are scheduled for a board meeting. The MEB consists mainly of two parts, the board with about 17 highly educated professors who are making the final decision on an application, and the drafters of the report, me as a regulator et cetera who are doing the work and prepare the reports for the board. There the assessment is discussed and we mostly draw a list of questions to the company which they have to answer. After their reply, we do a reassessment and a final decision is taken.
But a lot of decisions are made in the EU. I just talked about the national procedure, that's when a company decides to make an application in only one member state, like for melatonin supplementation. But for example, Circadin, as a product that is registered in all member states of the European Union, has a centralized procedure. It means that an application is made in all member states at the same time and an assessment is done by one member state. They draw out a report which is being discussed on a European level in a specific meeting at the EMA [European Medicines Agency]. A company also has the option to make the applications only in a few member states, then one member state will make reports which are circulated to the other member states and are asked what they think of the assessments.
Katrin: You told us that the EMA and, for example, the MEB have different medicines that they evaluate, so they don't interfere. But if the MEB authorized a medicine, could the EMA object to it?
Leon Bongers: Normally the EMA or another member state is not even aware of such a decision. We issue marketing authorizations to a company. But it might happen for example when a member state in Europe considers that a product does more harm than that it is efficacious. Then the member state has the opportunity to refer a commission in Europe, the CHMP, the European Committee for Medicinal Products for Human Use. The CHMP advises the European Commission which can take the final decision on whether a medicinal product can be used for a certain indication.
Katrin: Could you say something about the risks of taking melatonin as a supplement without a physician's advice, or are there also benefits?
Taina Mattila: In principle, there is no specific risk in short-term use. But for example, the long-term risks with children are not completely known, for example for maturation. And I think when you take melatonin in the wrong way or in a wrong time it can also influence your own circadian rhythm. In that way, it can be harmful.
Taking melatonin for a sleep problem might deprive yourself of an effective treatment that a physician could be able to give to you. Soft measures for improving sleep could be nightly rituals and other non-medicinal measures. Basically, the benefits of melatonin have really conclusively in my personal opinion been only shown in jet lag and to some extent to the indication of Circadin at the moment. So if you ask about short-term safety risks we are not that worried, but we are with using it for a long time and with indications where it might not have any kind of effects.
Katrin: I read that a side effect of taking melatonin is blood in the urine. Do you know where that comes from?
Taina Mattila: Unfortunately I don't know. But of course melatonin is a hormone, that is involved in a lot of different systems in the body and has the potential to affect them.
Katrin: Circadin is only allowed from the age of 55 years onwards. When the company wanted it to be allowed, they only asked to allow it for the age of 55 years onwards. Can you imagine why they took this limit and not for example and didn't allow it for all adults?
Taina Mattila: The main large trial was performed in patients over 55 years of age. So the data for lower age groups was not available to such an extent that it could be approvable. There was a lot of discussion in the CHMP and in the end, it was approved with a majority decision. You should also know that the indication is specifically for insomnia characterized by poor sleep quality. So it is not an overall insomnia indication and it is limited to age.
Katrin: Is there a discussion about lowering the age limit?
Leon Bongers: In general one can say that the age limit will not shift as long as the company is not asking for it because a change or an application is made by a company. And as long as a company does nothing, the age limit will not change. So they have to substantiate why the age limit could be lower. But I think they have no chance of lowering it in normal healthy people.
Taina Mattila: They would be asked to show some new data for it, so I don't think the company is interested in doing studies for that.
Katrin: I recently read that Germany said that that there are not so many studies, and also there are no long-term studies. What can you tell me about it?
Taina Mattila: There are many studies being done, some positive, some negative.
In most kinds of sleep disorders, the efficacy is inconclusive. It is unclear whether the effects are clinically relevant. So, for example, a patient falls asleep 10 minutes faster than he does normally, does it have an effect on the patient's wellbeing or functioning? What is the threshold how much faster you have to fall asleep in order to improve your quality of life? What I've seen so far is that in jetlag there is the strongest evidence of efficacy.
Katrin: Did you hear that taking Melatonin could be also beneficial for shift workers and have you heard of other benefits?
Taina Mattila: On shiftwork, there is not enough evidence for efficacy based on what I have seen in the literature.
Leon Bongers: There is EFSA, that's the European authority for food products and supplements. They have decided on the indication of the reduction of sleep onset [the time you are still awake after going to bed]. It seems that it is indeed reduced by melatonin. But so far the MEB has not accepted the sleep onset time reduction as an indication for a medicinal product and therefore it cannot be registered for this indication. But there was a lot of discussion in the MEB. So far we have not accepted it as an indication for melatonin as a medicinal product. But it's the most important reason to use it as a supplement.
Interview with a local radio station
Bringing synthetic biology, iGEM and our project to the public eye is a big part of human practices. On August 1st we met with a local radio station, the "Hochschulradio", in Aachen and had an interview with them. We had the opportunity to present our project und talk about the importance of melatonin to a wide audience. Furthermore we talked about iGEM and what it means to us.
Aachen Engineering Award
Informing public personae about iGEM
On September 7, 2018, we met Emmanuelle Marie Charpentier at the Aachen Engineering Award. She impressed and motivated us very much with her work and her character. It was not only the first time that a woman, but also a person with a biological and chemical background was awarded this prize. This has given us additional confidence for the future in the role of biosciences and equality. Besides that, we briefly presented our project and iGEM to Klaus Radermacher, Head of Medical Technology at RWTH University, and to the new Rector Ulrich Rüdiger.
After a long period of researching, we finally met most of the German iGEM-teams in June at Marburg.
We not only got to know many inspiring people, but also had the opportunity to discuss our projects with them.
Especially, the sharing of experiences and failures would help us later on in our journey.
Furthermore, various scientists and organizations joined the meetup and presented to us their experiences and advice. We learned how to handle steps backwards and how they can improve a scientist's work.
A big thanks to the iGEM team Marburg for organizing and hosting this great event!
Only one month after the meetup in Marburg we went to the European meetup
in Munich where we had a great time. We had the chance to meet the German teams again as well as meeting even
more awesome young researchers, in particularly, the iGEM team of Utrecht with whom we started a collaboration afterwards.
In addition, we met a bunch of scientists and entrepreneurs who shared their wisdom with us. We listened to talks about current topics in the field of synthetic biology and learned new skills at workshops.
We thank iGEM LMU and TU Munich for the organization of this thrilling weekend!
meeting prospective researchers
"Jugend Forscht" encourages and inspires scientifically talented young people under the age of 21.
Like the iGEM competition, young students develop a project and throughout the
competition meet up with entrepreneurs, scientists and other qualified people to improve their idea.
It is Germany’s greatest competition in promoting young scientists.
In May, a group of participants visited our laboratories and discussed their ideas with us. Additionally, we presented our project and Marco, one of our advisors, gave them a tour through our laboratories.
Seeing young people who have this level of interest in sciences and new approaches to current issues was an inspiring and reassuring experience. We wish them success in the competition!
Teaching the basics of microbiology
To meet the challenges of the future, biologic applications are going to be more and more relevant. Thus, it is essential to make this work field interesting for young people. With a school project, we tried to make the field of synthetic biology more appealing for them.
Since we were very surprised about the major role of melatonin in the human body and the little familiarity in the public, we took this opportunity to inform our audience.
At the beginning of September, we went to 10th-grade students at the Herzogenrath Highschool to show them the fundamentals of lab work. We carried out the lessons on three different days.
At the beginning of the first day, we presented the schedule for the upcoming one and a half weeks. After a small introduction about us, we talk about safety in a laboratory, working sterile and different media types for the cultivation of microorganisms. We split the class into groups of four students. First, the students weighed out the different components to prepare a YPD medium in Petri dishes. We autoclaved the media and explained the physical principles of autoclavation. In the end, the pupil poured the YPD medium into the Petri dishes.
On the second day, the students inoculated the Petri dishes. Every group had four Petri dishes: one plate which was exposed to the air, another which was used to test the effect of ampicillin on the growth of microorganisms, and another two where they could test the contamination of different surfaces. Furthermore, we explained the functionality of antibiotics. The plates were incubated at 30°C.
Seven days later we evaluated the plates and talked about the different organisms that grew on the Petri dishes. To get a closer look, we used a light microscope to analyze how their morphology was multifaceted. After the students finished their drawings, we presented our project. The students were very interested in the topic and we continued discussing about synthetic biology and the different fields of research.
German Academic Exchange Service
On 20th September a polish student group visited the RWTH with the help of the DAAD (German Academic Exchange Service). We had the possibility to present our project along with other scientists from the Abbt Schwaneberg Institute. We talked about what iGEM is in general, the challenges and opportunities an iGEM project gives and what our project this year is particularly about. The students were very interested and had many different questions.
March for Science
movement for evidence-based politics and free research
On April 14th, we went to Cologne to attend the "March for Science".
With self-made signs and banners our goal was to draw attention to the importance of science in our society.
Fake-news, alternative-facts and populism raise fear and antipathy against research. To deal with those problems, speeches on science were given. Speakers included science-journalist Ranga Yogeshwar and criminal-biologist Mark Benecke among others.
After this inspiring event, we used the possibility to get to know the iGEM-teams from Duesseldorf and Bielefeld and exchanged ideas and visions about our projects.
Integrated Human Practices
Finding the idea
The first steps towards a certain project idea
In February 2018 we started brainstorming to find a project that could potentially transform people’s lives.
Ranging from a car fueled by hydrogen produced by cyanobacteria, over the decrease of the detection-time of slowly growing pathogenic bacteria we had plenty of ideas. We saw the greatest potential in the simplification of the diagnosis of a melatonin underproduction since the current measurement takes up to six weeks.
One of our team members, Biel Badia Roigé, had already experienced this issue. The stunning findings in the past decades revealed a strong correlation with numerous diseases, so our biosensor could speed up the diagnosis of multiple diseases. The idea of a faster, cheaper and more versatile method of melatonin-measurement also resonated with our PI’s Dr. Wiechert, Dr. Schwaneberg and Dr. Bank. Our first milestone was achieved.
Getting insights from a medical doctor
Prof. Dr. Groezinger is a senior physician in the psychiatric polyclinic.
Some of his research fields are sleep physiology and sleep medicine as well as sleep and affective disorders.
He also is a member of the European Sleep Research Society.
We visited him to learn about the use of melatonin measurement as a diagnostic marker in different diseases. We were shocked to hear that the University Hospital Aachen - being one of the largest clinics in Europe - does not perform any melatonin measurements. Samples for melatonin measurement have to be shipped to a medical laboratory 73 km away, to the Stein Labor in Moenchengladbach.
He explained to us how a melatonin sample is taken: traditionally, saliva samples are used, since there is a linear correlation of melatonin concentration in serum and saliva. The melatonin concentration found in saliva is 30% the concentration found in serum. Patients have to collect the samples themselves at home. At 2 a.m. they have to interrupt their sleep to give a saliva sample into the tubes they were provided with.
Taking just one sample is very inaccurate to deliver a substantiated diagnosis, but the financial restrictions are a great barrier for medical professionals for analyzing multiple samples. As we got to know later from a leading scientist in the field of melatonin research, Dr. Dario Acuña, for a reliable diagnosis, six samples, given with a two hours break in between each sample, are necessary. From Prof. Dr. Groezingers point of view, the high cost of an adequate number of melatonin measurements is the reason for the rare usage of this diagnostic method. Therefore the internal laboratory of the University Hospital Aachen does not gather a sufficient amount of samples to make melatonin measurements cost-efficient - the most widely used assay for melatonin measurement is the Enzyme-Linked Immunosorbent Assay (ELISA), and it is mostly available in 96-well strip plates.
For further infromation on different laboratory methods for melatonin measurement read our article about Dr. Dario Acuña.
Juelich Research Center
presenting and discussing ideas at the institute for bio and geo sciences
After weeks of research on the detection of melatonin in the human body, we came up with three possible mechanisms to use in our biosensor.
- using the MT1 membrane receptor with its G-protein coupled cascade
- using beta-arrestine binding to the activated MT1 receptor
- using the transcription factor RZR
On May 7th, we went to Juelich Research Center to discuss those ideas with experts,
to see which approach is most suitable in our project and to work out what difficulties we would have to face.
After a warm welcome of Michael Osthege, a former iGEM-Team member of RWTH Aachen in 2014 and 2015, and some basic chat about how to organize the team, we went to see Dr. S. Binder, founder of SenseUp, who gave insights into his StartUp. Afterwards, we presented our ideas to Prof. M. Pohl (biocatalysis and biosensors), Jun.-Prof. D. Kohlheyer (Microscale Bioengineering), Dr. Drepper from Institute for Molecular Enzyme Technology IMET (Bacterial Photobiotechnology) and Dr. J. Marienhagen (Synthetic Cell-factories).
With their advice, we figured out that using the cascade would be too time-consuming and unspecific. The fewer components, the better because intermediate steps work as a black-box for us. We would not be able to see if other substances interfered with our receptor in between. Furthermore, if we did not have a signal at all, we would have serious difficulties to localize the steps, where problems could occur. Because of this, it would not be specific enough and evidence that the detected signal came from melatonin would not be given. In addition, we learned that using living cells for quantitative measurement could be tricky. We decided to focus on beta-arrestin binding and on RZR and to abolish the idea of a G-protein coupled cascade.
Using luciferase under the control of the Estrogen Response Element as reporter
During our first months of research we noticed a research group in the Aalto University (Helsinki),
who developed a yeast-cell based assay for the detection of different analytes, i. e. Estrogen, using different nuclear receptors.
We decided, that the system would be suitable for our project, as we also planned to use the specific nuclear receptor RZR (Retinoid-related orphan receptor-beta) for the detection of melatonin.
After contacting the research group, they directly send us their modified strain (BMA64-1A), so that we could use the integrated firefly luciferase gene as a reporter under the control of the Estrogen Response Element (ERE).
Status quo of melatonin measurements
While working on our biological approach using living cells to detect melatonin in saliva samples,
the next logical step was to gather the opinion of the people that are ultimately going to perform the measurements -
Dr. med. Josef van Helden leads the department of endocrinological measurements in the Stein Labor (German for laboratory) in Moenchengladbach and was kind enough to have an interview with us.
Since we were concerned about whether tubes, in which saliva samples are given, need a special coating, we got Dr. Josef van Helden’s opinion in this. In his lab, salivettes are primarily used, considering they are easy to use for the patient (a fiber roll is placed inside the mouth to soak it with saliva, and then it's placed back inside the tube). But the tubes itself does not have a special coating, because melatonin does not react with polyethylene.
For a melatonin measurement serum, saliva or urine can be used. Since saliva delivers reliable measurement results and is most convenient.
Concerning the transport conditions, patients have to make sure, that their saliva sample is transported under 10°C. If saliva samples are saved at a temperature under -20°C, they can be stored for a long period of time.
The most commonly used method for melatonin measurements is Enzyme-Linked Immunosorbent Assay (ELISA). High-Performance Liquid Chromatography (HPCL) and Gas chromatography-mass spectrometry (GC-MS) are two further methods that are used for melatonin measurements, but since they are costly they are not the preferred choice. We got further insides about the advantages and disadvantages of the sensitivity of these methods from Dr. Dario Acuña. ELISA is mostly available in 96-well strip plates. If fewer samples are analyzed than a kit offers, it is inherently linked to a higher cost per sample. Thus, laboratories wait till 96 samples are gathered. In case this takes a long time, the patient has a long waiting time till the results of their measurement are available. Especially in the case of melatonin, this is a relevant point.
We also were interested in whether these laboratories use living cells for their measurements. Some measurements are performed with living cells, so our biological approach could indeed be used in medical laboratories.
Regarding Dr. Josef van Helden, the best solution for a melatonin measurement would be a device that could be placed in the doctor's office. The point of care diagnostic is a growing market, but there is no device yet, that allows to instantaneous measurements of melatonin.
Prof. Dr. Dario Acuña
Talking with the expert in melatonin research
Prof. Dr. Dario Acuña works at the University of Granada in Spain and is the leading scientist in the field of melatonin research.
He was the first researcher who investigated melatonin and its effects in the 1980s. During our research,
we read many of his scientific papers. Therefore, we wanted to interview him.
Due to the interview, we decided to use saliva samples for melatonin measurement. Moreover, it marked the start of our hardware project.
First of all, we discussed current melatonin measurement methods. The most common methods are ELISA, HPLC and UPLC combined with mass spectrometry. Depending on the sample fluid (blood, saliva or urine) each method has its benefits and drawbacks. Whereas ELISA works perfectly for melatonin metabolites in urine, it is not as specific in blood or saliva. There again, HPCL is often used for high levels of melatonin in blood. These high levels, however, only occur rarely. Dr. Acuña stated that mass spectrometry is the most accurate technique but is yet very expensive compared to ELISA and HPLC. Mass spectrometry is not a standard detection method and therefore only few laboratories can use this sensitive technique.
Accordingly, we asked about the best fluid to measure the melatonin level. He explained that saliva would be the best one, as it contains about 30% of the melatonin concentration in blood. Using saliva instead of blood is better for the patients as it is non-invasive. Urine only contains metabolites of melatonin and is not as accurate.
Furthermore, we learned about the process of measuring the melatonin levels. Usually, Dr. Acuna takes six samples of saliva of one patient and uses five assays of ELISA. It takes about one to two days from taking the samples to having the results. The price for one sample measured with mass spectrometry is around 90-100€. With 5-6 samples per patient, a melatonin measurement costs 600-800€ for only one patient.
Additionally, we asked Dr. Acuña about the correlation between melatonin and different diseases like Alzheimer’s and Parkinson’s.
He stated that for example, patients with Alzheimer’s disease have low levels of melatonin.
Melatonin can be used in those cases as a therapeutically drug. Dr. Acuña told us that there are different influences of melatonin on the course of the disease.
In the early stages of the loss of cognitive abilities, a dose of around 50-60 mg melatonin can help to stop the progression of it.
Besides, Dr. Acuña sees a desperate need for a more specific method. Except for mass spectrometry, the current techniques are standard scientific methods but have a lack of sensitivity. He believes that a device which is placed directly in the doctor’s office would redefine melatonin measurement.
Finally, we asked him about the future of melatonin measurement. He stated that society is gaining more awareness of the importance of melatonin. It is entering the drug market and is used more often for patients. Therefore, he demands a better measurement method.
Our talk with Prof. Dr. Acuña had a deep impact on our project. After the interview, we decided to measure the melatonin level in saliva as it is more accurate than urine and non-invasive compared to blood. Furthermore, we decided to engineer a point-of-care-diagnostic to speed up the measurement process. This was the very beginning of our hardware project.
Prof. Dr. Wiechert
Introduction to the SPR method for a cell-free biosensor
After talking to Dr. Acuna, we realized that a cell-free solution would be even better for a point-of-care-diagnostic device.
Therefore, we met with Prof. Dr. Wiechert, who is an expert on hardware solution.
He introduced us to the analysis technique SPR (Surface Plasmon Resonance). During our research, we concluded that LSPR (Localized Surface Plasmon Resonance) is even more suitable for our hardware device. To learn more about this technique, please look at the hardware page.
Prof. Dr. Wiechert explained that only a few companies use LSPR and that their products are expensive (about 200,000€ to 300,000€).
Furthermore, we discussed other approaches like the Molecular Beacon Method. But he advised us not to use it due to its complexity.
Besides, he introduced us to Prof. Bott who helped us in the next step.
Meeting with Prof. Dr. Bott in Juelich
Choosing RZR as a receptor for our hardware device
After getting the SPR idea from Professor Wiechert we visited Professor Michael Bott in the Juelich Reasearch Center, who leads the systemic microbiology there. He told us more about this technology and we discussed with him different melatonin receptors to use. We learned that working with the MT1 receptor should be avoided because it is a membranous protein. So for anchoring it, we would need to create an artificial membrane, which would be a tricky task. Professor Bott suggested using preferably our other melatonin receptor, the transcription factor RZR.
Mr. Scholz and Dr. Merget
In August we started looking for partners to build our gold nanostructure.
We had a lot of luck to talk with experts in this field from the Institute for Semiconductors (IHT)
and the Institute of Integrated Photonics (IPH): Dr. Florian Merget of the IPH and Stefan Scholz of the IHT.
We met multiple times to talk about our concept.
At first, our hardware idea was to build an optic fiber based LSPR System. In this setup, the gold nano structure is placed on top of a small optic fiber and the light is guided from the lamp to the nano structure by the glass fiber. Some light is reflected back by Plasmon Resonance, guided through the fiber and then analyzed in the spectrometer. The advantage is that the optical handling and alignment is really easy. No moving parts and lenses that need to be in focus are needed. That is why we at first preffered this method.
After presenting this idea, we got to talk about how commercial chips like those inside a computer, smartphone or car are produced. Dr. Merget and Mr. Scholz had a lot of insight to this. They explained that in principle it would be possible to structure Au nanoparticles on top of a small 0.14 mm fiber with experimental electron-beam processing (e-beam). But this would prohibit using normal commercial litography systems like UV-litography which are state of the art right now.
All commercial litography systems are optimized to work with thin wafers.
The space inside these machines prohibits placing long fibers in them.
The vast share of the cost of producing nano structures lies in the price of the machines.
If standard semiconductor machines are used like UV-litography,
then the price per chip in mass production can be cut to a couple of dollars.
During the discussion, we changed our setup from placing the Au nano structure on top of the fiber to placing it on standard glass wafers. This greatly reduces the cost of the wafer and markets the wafer as a disposable part, that you change once you want to measure a different molecule.
In another meeting, Mr. Scholz also gave us a tour of their clean room and machines. It is really impressive what kind of effort goes into making those small nano structures. Just the machines for clean non-ionized water are as big as two student dorms.
Hardware Optimization: From Reflection to Transmission
We met with Dr. Mourran, group leader for Thermoplasmonics of Nanoparticles at the DWI Leibniz Institute for Interactive Materials.
His group uses Plasmon Resonance to liquify hydrogels.
He is an expert in the application of Plasmon Resonance and the different setups available.
With his input we changed our approach from reflection to transmission.
The reason we approached him, was to talk about a possible partnership to manufacture the Au nano particles. He was quite intrigued, but could not help us with the manufacturing, as they did not have the necessary machinery. But he could lend us his expertise. Firstly, he taught us a lot about the actual physics, what Plasmon Resonance is and how they use it. With his applied knowledge in using Plasmons for thermal purposes, we learned how all the different parameters influence Plasmon Resonance.
Secondly, during intense discussion we further evolved our setup. Up until that point, we wanted to analyze the reflected light with the spectrometer. This light is scattered by Plasmon Resonance in a 90° angle from the wafer. It is a clear signal, but it is very weak. Furthermore, this means that the incident light beam, that excites the Plasmons, and the reflected light beam are running inverse parallel. Because of this, a beam splitter is needed. As our spectrometer is not extremely sensitive, Dr. Mourran advised that we should consider a transmission setup. We followed his advice as this also simplified the setup. The beam splitter is not needed in this case, and this results in one component less that needs to be perfectly adjusted.
Searching for Fano Resonance through Simulation
Dr. Mouran recommended us to talk to another expert in this field,
who could give us some quantifiable data at which wavelength the Plasmon Resonance occurs.
He put us in contact with Dr. Chigrin, group leader for Theory of complex materials at the DWI Leibniz Institute for
After a few minutes into the presentation of our proposed nanogold structure layout, Dr. Chigrin immediately started talking about how we could develop such a sensor without running simulations first. We were a bit confused as plasmon resonance occurs in nanoparticles always, the resonance wavelength changes depending on size and shape. Then we realized that we were talking about two different phenomena.
Dr. Chigrin thought that we wanted to use the phenomena of Fano resonance in our sensor, because we had a periodic hexagon grid of discs with 160 nm diameter and 400 nm distance from each other. We had never heard about this and were curious. Fano resonance is an interference phenomenon. It occurs if the plasmon resonance wavelength meets the Bragg condition. This could greatly enhance the peak of our signal (figure 1).
The zone in which the Bragg condition is met, is quite small and dependent on a lot of factors. A college of Dr. Chigrin, Sebastian Meyer, did a simulation search for the distances where the bragg condition is met. You can read more about Fano resonance and the simulation results, that Sebastian Meyer did, in our wiki.
Suggestions for further improvements
Taking all the feedback into account, our project does not have to end just yet.
We could engineer some improvements to our technique to make it market-ready.
Before we can sell our product to doctor’s offices, we must make some adjustments to the device itself as well as to the production process. Presumably, we will provide only a few practices with our hardware at first to get feedback from users before launching our product. Afterwards, we will be able to write an user-friendly software for the most pleasant user-experience. It should be as easy to handle as possible to ensure the frequently use of Melasense.
Furthermore, our technique is applicable to more hormones, for example estrogen and cholesterol. We could engineer a multi-hormone measurement method as a point-of-care-diagnostic to not only redefine melatonin measurement, but also the measurement of a bunch of similar hormones.
In the future, the measurement of those hormones could be integrated in the regular health check to raise awareness of the importance of hormone balance.
As our final goal, we want to engineer a bracelet with an implemented chip which could measure the melatonin level of patients overnight multiple times to quantify the results and to take point-of-care-diagnostic to the next level.