Mid-Infrared CRyptophane-enhanced On-chip Sensor

Økningen i klimagasutslipp er alarmerende både for vitenskapen og befolkningen. MICRO-Sense-prosjektet adresserer dette temaet ved å utvikle en ny generasjon sensorteknologi som kan forenkle identifisering og kvantifisering av utslippskilder. Den genererte kunnskapen skal bidra til å nøyaktig vurdere utslippsbudsjettet og forbedre dagens klimascenarioer. Sensorene i prosjektet er basert på interaksjon av infrarødt lys med gassmolekyler på en fotonisk miniatyrbrikke (optisk brikke? mikrobrikke?). Sensorene er derfor små og lette, og samtidig pålitelige, selektive og opptil 10 000 mer følsomme enn eksisterende sensorer med sammenlignbar pris og størrelse. Basert på nye, spesialdesignede tynnfilmbølgeledere, har sensorene demonstrert deteksjon av metan ned til 300 ppb og av karbondioksid ned til 30 ppb. Det er første gang at mikrosensorer på en brikke kan måle disse to klimagassene så nøyaktig, med deteksjonsgrense godt under den atmosfæriske konsentrasjonen av disse gassene. I tillegg har vi vist at sensoren kan skille mellom forskjellige karbondioksid-isotoper, med 0,3‰ presisjon i isotopforholdet. Dette kan sammenlignes med presisjonen til store, avanserte og kostbare instrumenter. Med dette resultatet markerer MICRO-Sense en ny milepæl innen sporgassdeteksjon på en brikke, som åpner for tettere sensornettverk og sensorutplassering i vanskelig tilgjengelige områder som Arktis. Prosjektet var ledet av Jana Jagerska ved Institutt for fysikk og teknologi, UiT. Prosjektbudsjettet på 13 millioner kroner, hvorav 8 millioner fra NFR, ble brukt til å finansiere deler av prosjektlederstillingen, 2 ph.d.-stillinger, fremstilling av nanofotonikk for mikrosensorene, og utstyr til et nytt laboratorium for fotonikk i det midtre infrarøde området. Mer informasjon om prosjektet er tilgjengelig på nettsiden: http://site.uit.no/onchipsensing/projects/micro-sense/

The most important outcome of the project is a sensor chip demonstrated for detection of trace concentrations of methane and carbon dioxide. This sensor chip achieves detection limits down to 30 part-per-billion concentration levels, which is an enormous improvement (approximately four orders of magnitude!) compared to existing spectroscopic sensors in the same size category. This result will facilitate significant miniaturization of spectroscopic trace gas detectors, making them more affordable, more abundant, and possibly deployable in networks. An additional unique property of the developed sensors is an extremely small sample volume down to micrometers, which is a dramatic reduction compared to tens of millilitres to litres of comparable bulk instruments. The impact of the work is primarily in climate research, which will welcome denser sensor networks to better identify and quantify gas emissions and constrain existing climate models. The on-chip sensors may also be applied in new research areas such as organoid or microbiology research, where current laser spectroscopic instruments are not applicable due to too large sample volumes. Finally, applications in industrial monitoring and process control such as monitoring of gas leaks or combustion efficiency are foreseen. The project has also had a substantial impact on the development of nanophotonics and nanotechnology as fields of research and study at UiT. UiT has been integrated in national networks (research schools Nanonetwork, TNNN), plans construction of a cleanroom facility, and opening of a new study program on nanophotonics and nanotechnology. Existing collaborations were strengthened through research stays (University of Southampton, NTNU) and new collaborations were established (Stanford University, University of Malaga). Commercialization of the results either through an industrial partnership or creation of a startup company is envisaged.

Mid-infrared laser spectroscopy is a well-established technique for trace gas detection; it is inherently fast, non-invasive and undisputedly the most sensitive and selective. The key problem is that current mid-infrared spectrometers are almost exclusively realized using free-space optics, and therefore remain costly and bulky. MICRO-Sense project aims to bring the powerful mid-infrared sensing onto a photonic chip, targeting both ultimate sensitivity and minimal footprint. Yet, by law of nature, the sensitivity scales with the optical interaction length, which eventually translates into the instrument size. Maintaining high sensitivity upon miniaturization is the principal challenge of the project. This will be addressed by: (i) An innovative waveguide design optimized for maximum optical field interaction with the surrounding environment, (ii) Co-doping the waveguide cladding with cryptophanes, i.e. specially synthesized supra-molecules that can selectively trap and pre-concentrate methane. Atmospheric methane sensing has been chosen as a test-bed application for the project due to its relevance in the Arctic, where the monitoring of methane release from thawing permafrost and ocean seabed is of primary interest (CAGE). However, the unique combination of on-chip mid-infrared tuneable laser spectroscopy with an enrichment layer is an absolute novelty, making MICRO-Sense high impact far beyond methane gas detection. MICRO-Sense is a strongly inter-disciplinary project with focus across the fields of photonics, spectroscopy and chemistry, having a high degree of novelty, but also involving technological challenges and associated risks. Yet, the chance of success is maximized by the ideally matching scientific background of the PI and a unique team of scientists, word-leading experts in all relevant areas of the project.