skip to main content


Title: Ultrasensitive multispecies spectroscopic breath analysis for real-time health monitoring and diagnostics

Breath analysis enables rapid, noninvasive diagnostics, as well as long-term monitoring of human health, through the identification and quantification of exhaled biomarkers. Here, we demonstrate the remarkable capabilities of mid-infrared (mid-IR) cavity-enhanced direct-frequency comb spectroscopy (CE-DFCS) applied to breath analysis. We simultaneously detect and monitor as a function of time four breath biomarkers—CH3OH,CH4,H2O, and HDO—as well as illustrate the feasibility of detecting at least six more (H2CO,C2H6, OCS,C2H4,CS2, andNH3) without modifications to the experimental apparatus. We achieve ultrahigh detection sensitivity at the parts-per-trillion level. This is made possible by the combination of the broadband spectral coverage of a frequency comb, the high spectral resolution afforded by the individual comb teeth, and the sensitivity enhancement resulting from a high-finesse cavity. Exploiting recent advances in frequency comb, optical coating, and photodetector technologies, we can access a large variety of biomarkers with strong carbon–hydrogen-bond spectral signatures in the mid-IR.

 
more » « less
Award ID(s):
1665271 1734006
NSF-PAR ID:
10305217
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
Proceedings of the National Academy of Sciences
Date Published:
Journal Name:
Proceedings of the National Academy of Sciences
Volume:
118
Issue:
40
ISSN:
0027-8424
Page Range / eLocation ID:
Article No. e2105063118
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    M dwarfs are common host stars to exoplanets but often lack atmospheric abundance measurements. Late-M dwarfs are also good analogs to the youngest substellar companions, which share similarTeff∼ 2300–2800 K. We present atmospheric analyses for the M7.5 companion HIP 55507 B and its K6V primary star with Keck/KPIC high-resolution (R∼ 35,000)K-band spectroscopy. First, by including KPIC relative radial velocities between the primary and secondary in the orbit fit, we improve the dynamical mass precision by 60% and findMB=88.03.2+3.4MJup, putting HIP 55507 B above the stellar–substellar boundary. We also find that HIP 55507 B orbits its K6V primary star witha=383+4au ande= 0.40 ± 0.04. From atmospheric retrievals of HIP 55507 B, we measure [C/H] = 0.24 ± 0.13, [O/H] = 0.15 ± 0.13, and C/O = 0.67 ± 0.04. Moreover, we strongly detect13CO (7.8σsignificance) and tentatively detectH218O(3.7σsignificance) in the companion’s atmosphere and measure12CO/13CO=9822+28andH216O/H218O=24080+145after accounting for systematic errors. From a simplified retrieval analysis of HIP 55507 A, we measure12CO/13CO=7916+21andC16O/C18O=28870+125for the primary star. These results demonstrate that HIP 55507 A and B have consistent12C/13C and16O/18O to the <1σlevel, as expected for a chemically homogeneous binary system. Given the similar flux ratios and separations between HIP 55507 AB and systems with young substellar companions, our results open the door to systematically measuring13CO andH218Oabundances in the atmospheres of substellar or even planetary-mass companions with similar spectral types.

     
    more » « less
  2. Abstract

    The formation and evolution of post-solitons has been discussed for quite some time both analytically and through the use of particle-in-cell (PIC) codes. It is however only recently that they have been directly observed in laser-plasma experiments. Relativistic electromagnetic (EM) solitons are localised structures that can occur in collisionless plasmas. They consist of a low-frequency EM wave trapped in a low electron number-density cavity surrounded by a shell with a higher electron number-density. Here we describe the results of an experiment in which a 100 TW Ti:sapphire laser (30 fs, 800 nm) irradiates a0.03gcm3TMPTA foam target with a focused intensityIl=9.5×1017Wcm2. A third harmonic (λprobe266nm) probe is employed to diagnose plasma motion for 25 ps after the main pulse interaction via Doppler-Spectroscopy. Both radiation-hydrodynamics and 2D PIC simulations are performed to aid in the interpretation of the experimental results. We show that the rapid motion of the probe critical-surface observed in the experiment might be a signature of post-soliton wall motion.

     
    more » « less
  3. Abstract. Photoacoustic spectroscopy (PAS) has become a popular technique for measuringabsorption of light by atmospheric aerosols in both the laboratory andfield campaigns. It has low detection limits, measures suspended aerosols,and is insensitive to scattering. But PAS requires rigorous calibration to beapplied quantitatively. Often, a PAS instrument is either filled with a gasof known concentration and absorption cross section, such that the absorptionin the cell can be calculated from the product of the two, or the absorptionis measured independently with a technique such as cavity ring-downspectroscopy. Then, the PAS signal can be regressed upon the known absorptionto determine a calibration slope that reflects the sensitivity constant ofthe cell and microphone. Ozone has been used for calibrating PAS instrumentsdue to its well-known UV–visible absorption spectrum and the ease with whichit can be generated. However, it is known to photodissociate up toapproximately 1120nm via the O3 + hν(&gt;1.1eV)O2(3Σg-) + O(3P) pathway, which is likely tolead to inaccuracies in aerosol measurements. Two recent studies haveinvestigated the use of O3 for PAS calibration but have reachedseemingly contradictory conclusions with one finding that it results in asensitivity that is a factor of 2 low and the other concluding that it isaccurate. The present work is meant to add to this discussion by exploringthe extent to which O3 photodissociates in the PAS cell and the rolethat the identity of the bath gas plays in determining the PAS sensitivity.We find a 5% loss in PAS signal attributable to photodissociation at 532nmin N2 but no loss in a 5% mixture of O2 in N2.Furthermore, we discovered a dramatic increase of more than a factor of 2in the PAS sensitivity as we increased the O2 fraction in the bathgas, which reached an asymptote near 100% O2 that nearly matched thesensitivity measured with both NO2 and nigrosin particles. Weinterpret this dependence with a kinetic model that suggests the reason forthe observed results is a more efficient transfer of energy from excitedO3 to O2 than to N2 by a factor of 22–55 depending onexcitation wavelength. Notably, the two prior studies on this topic useddifferent bath gas compositions, and although the results presented here donot fully resolve the differences in their results, they may at leastpartially explain them.

     
    more » « less
  4. Abstract

    The sensitivity of urban canopy air temperature (Ta) to anthropogenic heat flux (QAH) is known to vary with space and time, but the key factors controlling such spatiotemporal variabilities remain elusive. To quantify the contributions of different physical processes to the magnitude and variability ofΔTa/ΔQAH(whereΔrepresents a change), we develop a forcing-feedback framework based on the energy budget of air within the urban canopy layer and apply it to diagnosingΔTa/ΔQAHsimulated by the Community Land Model Urban over the contiguous United States (CONUS). In summer, the medianΔTa/ΔQAHis around 0.01K W m21over the CONUS. Besides the direct effect ofQAHonTa, there are important feedbacks through changes in the surface temperature, the atmosphere–canopy air heat conductance (ca), and the surface–canopy air heat conductance. The positive and negative feedbacks nearly cancel each other out andΔTa/ΔQAHis mostly controlled by the direct effect in summer. In winter,ΔTa/ΔQAHbecomes stronger, with the median value increased by about 20% due to weakened negative feedback associated withca. The spatial and temporal (both seasonal and diurnal) variability ofΔTa/ΔQAHas well as the nonlinear response ofΔTatoΔQAHare strongly related to the variability ofca, highlighting the importance of correctly parameterizing convective heat transfer in urban canopy models.

     
    more » « less
  5. Sub-Neptunes are common among the discovered exoplanets. However, lack of knowledge on the state of matter inH2O-rich setting at high pressures and temperatures (PT) places important limitations on our understanding of this planet type. We have conducted experiments for reactions betweenSiO2andH2O as archetypal materials for rock and ice, respectively, at highPT. We found anomalously expanded volumes of dense silica (up to 4%) recovered from hydrothermal synthesis above ∼24 GPa where theCaCl2-type (Ct) structure appears at lower pressures than in the anhydrous system. Infrared spectroscopy identified strong OH modes from the dense silica samples. Both previous experiments and our density functional theory calculations support up to 0.48 hydrogen atoms per formula unit of (Si1xH4x)O2(x=0.12). At pressures above 60 GPa,H2O further changes the structural behavior of silica, stabilizing a niccolite-type structure, which is unquenchable. From unit-cell volume and phase equilibrium considerations, we infer that the niccolite-type phase may contain H with an amount at least comparable with or higher than that of the Ct phase. Our results suggest that the phases containing both hydrogen and lithophile elements could be the dominant materials in the interiors of water-rich planets. Even for fully layered cases, the large mutual solubility could make the boundary between rock and ice layers fuzzy. Therefore, the physical properties of the new phases that we report here would be important for understanding dynamics, geochemical cycle, and dynamo generation in water-rich planets.

     
    more » « less