Carnegie Mellon University
Browse

Accurate calibration and control of relative humidity close to 100% by X-raying a DOPC multilayer.

Download (2.11 MB)
journal contribution
posted on 2015-02-07, 00:00 authored by Yicong Ma, Sajal K. Ghosh, Sambhunath Bera, Zhang Jiang, Stephanie Tristram-NagleStephanie Tristram-Nagle, Laurence B. Lurio, Sunil K. Sinha

In this study, we have designed a compact sample chamber that can achieve accurate and continuous control of the relative humidity (RH) in the vicinity of 100%. A 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) multilayer can be used as a humidity sensor by measuring its inter-layer repeat distance (d-spacing) via X-ray diffraction. We convert from DOPC d-spacing to RH according to a theory given in the literature and previously measured data of DOPC multilamellar vesicles in polyvinylpyrrolidone (PVP) solutions. This curve can be used for calibration of RH close to 100%, a regime where conventional sensors do not have sufficient accuracy. We demonstrate that this control method can provide RH accuracies of 0.1 to 0.01%, which is a factor of 10-100 improvement compared to existing methods of humidity control. Our method provides fine tuning capability of RH continuously for a single sample, whereas the PVP solution method requires new samples to be made for each PVP concentration. The use of this cell also potentially removes the need for an X-ray or neutron beam to pass through bulk water if one wishes to work close to biologically relevant conditions of nearly 100% RH.

History

Publisher Statement

© Royal Society of Chemistry

Date

2015-02-07

Usage metrics

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC