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Interview: Beckett Colson and Dr. Anna Michel

How would you describe your research activities at the Woods Hole Oceanographic Institution (WHOI)?

Anna: In the Chemical Sensors Lab, we develop a variety of instruments to study the ocean. For example, we work on methane and greenhouse gas sensing in the ocean. More recently, we became interested in plastics detection. Tools such as lock-in amplifiers are too big to go to the ocean, but we use them in the laboratory for developing the instruments that will go to the field.

What is the potential of laser-based technologies for ocean research?

Anna: My background is laser-based sensing, which has a lot of potential for ocean research. Right now, there aren’t many oceanographic instruments for studying the ocean environment in terms of chemical content. This means that a lot of researchers collect samples and then bring them back to the laboratory to analyze. We’re really interested in how we can take measurements in the ocean and not rely on wet chemistry. With approaches such as optical-based sensing we can perform direct measurements: we know that this kind of technology works for gas sensing, and there are lots of interesting gases in the ocean. In fact, we’ve developed a number of carbon and methane sensors for deployment in the deep sea. For example, we have recently demonstrated an optical sensor based on hollow-core fibers for measuring dissolved gases in liquids, and we are excited to start analyzing the first results from measurements on a deep sea cruise. Then again, we’re not limited to laser-based sensing: the impedance sensing for microplastics project on which Beckett works is an example of a completely different sensing setup.

How does an interdisciplinary background help in this research field? Is it common?

Anna: I guess my background is more interdisciplinary than that of many others in this field, but I’d say that most of our research is interdisciplinary in the sense that, when we go to the sea, we bring a team including biologists, geologists, chemists – and that’s because for many of the sites where we work it is valuable to look at different angles. We’re also very focused on technology applications, which naturally pushes us a little more towards the interdisciplinary side.

Beckett: My background is primarily in mechanical engineering. I’d say that ocean research is definitely interdisciplinary in terms of fields of engineering because every time you build something to go to the sea you need to deal with all of the different sub-systems – there’s electronics, optics, software, mechanical bits, etc. Bringing something to the sea means dealing with this innately interdisciplinary place, which you cannot really understand by just considering the physics of ocean currents – it’s also about chemistry, and biology, and it’s hard to tell the story of how the ocean works without grasping the big picture. This is actually one of the aspects I like about our group: that we collaborate with so many different scientists.

Where do Zurich Instruments’ products enter the picture?

Beckett: We initially had an HF2LI Lock-in Amplifier for the gas sensing experiments, and then bought another one together with the HF2LI-MF Multi-Frequency upgrade option and the HF2TA Transimpedance Amplifier for the microplastics project. For the latter, the idea is to look at the electrical properties of microplastics directly in a flow of water: a lock-in amplifier offers a really convenient way to measure impedance as a function of frequency. In practice, we monitor the impedance between two electrodes sandwiching a continuous flow of water. As particles flow between the electrodes, they change the impedance. We can use the impedance change to tell the difference between biological particles - which we hope to see in abundance - and microplastics. The primary way to interpret the data is through known mixtures of water, some of which we intentionally spike with plastic microbeads. The long-term view is to integrate this kind of sensor into a field instrument that can measure a body of water or be driven around in a harbor to map the presence of microplastics, in the same way as you could do with other pollutants. We’re still in the lab testing phase with this project, but we’ve done some initial field tests…

Anna: Yes, we took out the HF2LI to a pond, along with really heavy battery power with us (see photos). As a piece of feedback to Zurich Instruments engineers, smaller lock-ins would be helpful! In the ocean, vehicles are large but every instrument they carry needs to be as small as possible.

Field testing the microplastics sensor.

Figure 1: Field testing the microplastics sensor at Grews Pond, Falmouth, USA. Chemical Sensors Lab member Sarah Youngs studies a microplastic water sample gravity-fed through a funnel to the flow cell (the small bright red circuit board in the photo to the right). The HF2LI and the HF2TA – both housed in the big black case – are used to measure the impedance as the water sample flows through the flow cell. On the laptop, the LabOne software allowed Sarah to look at the changes in the impedance signals as particles went through the flow cell.

What is it that you shouldn’t forget to pack for a field trip at sea?

Beckett: Remember to download music to your phone because streaming won’t be possible.

Anna: I’d recommend a good coffee cup!

Anna Michel

Dr. Anna Michel, Associate Scientist at the Department of Applied Ocean Physics and Engineering, and Chief Scientist for Deep Submergence at the National Deep Submergence Facility at the WHOI

Beckett Colson

Beckett Colson, MIT-WHOI Joint Program PhD student in the Chemical Sensors Lab at the WHOI

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