Towards chip-based salinity measurements for small submersibles and biologgers
2013 (English)In: International Journal of Oceanography, ISSN 1687-9406, E-ISSN 1687-9414, Vol. 2013, 529674- p.Article in journal (Refereed) Published
Water’s salinity plays an important role in the environment. It can be determined by measuring conductivity, temperature, anddepth (CTD). The corresponding sensor systems are commonly large and cumbersome. Here, a 7.5 × 3.5mm chip, containingmicrostructured CTD sensor elements, has been developed. On this, 1.5mm2 gold finger electrodes are used to measure theimpedance, and thereby the conductivity of water, in the MHz frequency range. Operation at these frequencies resulted in highersensitivities than those at sub-MHz frequencies. Up to 14 kΩ per parts per thousand salt concentration was obtained repeatedlyfor freshwater concentrations.This was three orders of magnitude higher than that obtained for concentrations in and above thebrackish range. A platinumelectrode is used to determine a set ambient temperature with an accuracy of 0.005∘C.Membranes withNichrome strain gauges responded to a pressure change of 1 bar with a change in resistance of up to 0.21Ω. A linear fit to data over7 bars gave a sensitivity of 0.1185Ω/bar with an R2 of 0.9964. This indicates that the described device can be used in size-limitedapplications, like miniaturized submersibles, or as a bio-logger on marine animals.
Place, publisher, year, edition, pages
Hindawi Publishing Corporation, 2013. Vol. 2013, 529674- p.
Conductivity, Temperature, Depth, CTD, Pressure, Marine, thin film, micro
Engineering and Technology
Research subject Engineering Science with specialization in Microsystems Technology
IdentifiersURN: urn:nbn:se:uu:diva-171740DOI: 10.1155/2013/529674OAI: oai:DiVA.org:uu-171740DiVA: diva2:512332
ProjectsDeeper Access, Deeper Understanding (DADU)
FunderMistra - The Swedish Foundation for Strategic Environmental Research