Tailored synthesis and characterization of selective metabolite -detecting nanoprobes for handheld breath analysis

2008 2008

Other formats: Order a copy

Abstract (summary)

The abnormality in the concentration of certain trace gases in human breath, so-called biomarkers, could provide clues to diagnose corresponding diseases. For example, elevated isoprene is a result of cholesterol metabolic disorders, acetone is the biomarker of type-1 diabetes and NO is related to asthma. Non-invasive human breath analysis for disease diagnostics requires selective sensors that respond rapidly and with extreme sensitivity to specific biomarker gases.

On the other side, tungsten trioxide (WO3) is a very important semiconducting metal oxide which has shown great potential in gas sensing applications. WO3 exists in a series of stable solid phases at different temperatures from α phase to ϵ phase and an unstable hexagonal phase (h-WO3). However, except extensively studied y-WO3, the properties of other phases are still not fully known, esp. ϵ-WO3 and h-WO3 whose structures are different from other phases.

This dissertation discusses the development of several selective biomarker sensors based on room temperature (RT) stable ϵ-WO3 and h-WO3 nanostructured materials.

Ferroelectric ϵ-WO3 nanoparticles were synthesized using the flame spray pyrolysis method. Although the ϵ-WO3 polymorph vanishes during heat treatment in pure WO3 products, chromium dopants were utilized to stabilize this phase. The resistive sensor based on 10at%Cr doped ϵ-WO3 nanoparticles was found to be very sensitive and selective to low concentrations of acetone (0.2-1ppm) compared to a series of interfering gases at 400°C. The proposed explanation for the materials selectivity to acetone is the likely interaction between the surface dipole of ferroelectric ϵ-WO3 nanoparticles and the highly polar acetone gas molecules.

Open structured h-WO3 nanoparticles were produced by acid precipitation method. It was found that h-WO 3 is very sensitive to NOx compared to other gases at 150°C due to the open tunnel structure of h-WO3. Such selectivity is lost at 350°C. Instead, the material is very sensitive and selective to isoprene gas at 350°C. A p-n transition was found when the working temperature of the sensor increased from RT to 350°C which could be related to the excessive surface oxygen of the product.

Finally, a handheld exhaled breath analyzer prototype has been developed for non-invasive disease diagnosis. Real-time monitoring of the gas concentration is demonstrated, making this invention a revolutionary, non-invasive, diabetes diagnostic tool.

Indexing (details)

Biomedical engineering;
Materials science
0541: Biomedical engineering
0794: Materials science
Identifier / keyword
Applied sciences; Breath analysis; Chemical sensors; Metabolite-detecting; Metastable phase; Nanoprobes; Tungsten trioxide
Tailored synthesis and characterization of selective metabolite -detecting nanoprobes for handheld breath analysis
Wang, Lisheng
Number of pages
Publication year
Degree date
School code
DAI-B 70/05, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
Gouma, Pelagia-Irene Perena; Halada, Gary
State University of New York at Stony Brook
University location
United States -- New York
Source type
Dissertations & Theses
Document type
Dissertation/thesis number
ProQuest document ID
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
Access the complete full text

You can get the full text of this document if it is part of your institution's ProQuest subscription.

Try one of the following:

  • Connect to ProQuest through your library network and search for the document from there.
  • Request the document from your library.
  • Go to the ProQuest login page and enter a ProQuest or My Research username / password.