skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.


Title: Monolithic Integration of Si3N4 Ring Resonator and On-Chip Fourier Transform Spectrometer for The Lab-On-A-Chip Biosensor
We demonstrated the monolithically integrated biosensor with micro-ring-resonator (MRR) and spatial-heterodyne Fourier-transform-spectrometer (SH-FTS) on Si3N4-on-SiO2, substituting the external optical spectrum analyzer. The spectrum is retrieved from SH-FTS with the bulk sensitivity of 42.9 nm/RIU.  more » « less
Award ID(s):
1932753
PAR ID:
10346766
Author(s) / Creator(s):
;
Editor(s):
Jiang, Wei; Alan Wang
Date Published:
Journal Name:
Cleo
ISSN:
0928-9062
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. We define the Chow t-structure on the ∞-category of motivic spectra SH(k) over an arbitrary base field k. We identify the heart of this t-structure SH(k)c♡ when the exponential characteristic of k is inverted. Restricting to the cellular subcategory, we identify the Chow heart SH(k)cell,c♡ as the category of even graded MU2∗MU-comodules. Furthermore, we show that the ∞-category of modules over the Chow truncated sphere spectrum 1c=0 is algebraic. Our results generalize the ones in Gheorghe–Wang–Xu in three aspects: to integral results; to all base fields other than just C; to the entire ∞-category of motivic spectra SH(k), rather than a subcategory containing only certain cellular objects. We also discuss a strategy for computing motivic stable homotopy groups of (p-completed) spheres over an arbitrary base field k using the Postnikov–Whitehead tower associated to the Chow t-structure and the motivic Adams spectral sequences over k. 
    more » « less
  2. Abstract Background The opioid epidemic has caused an increase in overdose deaths which can be attributed to fentanyl combined with various illicit substances. Drug checking programs have been started by many harm reduction groups to provide tools for users to determine the composition of their street drugs. Immunoassay fentanyl test strips (FTS) allow users to test drugs for fentanyl by either filling a baggie or cooker with water to dissolve the sample and test. The antibody used in FTS is very selective for fentanyl at high dilutions, a characteristic of the traditional use of urine testing. These street sample preparation methods can lead to mg/mL concentrations of several potential interferents. We tested whether these concentrated samples could cause false positive results on a FTS. Methods 20 ng/mL Rapid Response FTS were obtained from BTNX Inc. and tested against 4 different pharmaceuticals (diphenhydramine, alprazolam, gabapentin, and naloxone buprenorphine) and 3 illicit stimulants [cocaine HCl, methamphetamine, and 3,4-methylenedioxymethamphetamine (MDMA)] in concentrations from 20 to 0.2 mg/mL. The FTS testing pad is divided into 2 sections: the control area and the test area. Control and test area signal intensities were quantified by ImageJ from photographs of the test strips and compared to a threshold set by fentanyl at the FTS limit of detection. Results False positive results indicating the presence of fentanyl were obtained from samples of methamphetamine, MDMA, and diphenhydramine at concentrations at or above 1 mg/mL. Diphenhydramine is a common cutting agent in heroin. The street sample preparation protocols for FTS use suggested by many online resources would produce such concentrations of these materials. Street samples need to be diluted more significantly to avoid interference from potential cutting agents and stimulants. Conclusions Fentanyl test strips are commercially available, successful at detecting fentanyl to the specified limit of detection and can be a valuable tool for harm reduction efforts. Users should be aware that when drugs and adulterants are in high concentrations, FTS can give a false positive result. 
    more » « less
  3. Abstract Hydrogen bonding is a central concept in chemistry and biochemistry, and so it continues to attract intense study. Here, we examine hydrogen bonding in the H2S dimer, in comparison with the well-studied water dimer, in unprecedented detail. We record a mass-selected IR spectrum of the H2S dimer in superfluid helium nanodroplets. We are able to resolve a rotational substructure in each of the three distinct bands and, based on it, assign these to vibration-rotation-tunneling transitions of a single intramolecular vibration. With the use of high-level potential and dipole-moment surfaces we compute the vibration-rotation-tunneling dynamics and far-infrared spectrum with rigorous quantum methods. Intramolecular mode Vibrational Self-Consistent-Field and Configuration-Interaction calculations provide the frequencies and intensities of the four SH-stretch modes, with a focus on the most intense, the donor bound SH mode which yields the experimentally observed bands. We show that the intermolecular modes in the H2S dimer are substantially more delocalized and more strongly mixed than in the water dimer. The less directional nature of the hydrogen bonding can be quantified in terms of weaker electrostatic and more important dispersion interactions. The present study reconciles all previous spectroscopic data, and serves as a sensitive test for the potential and dipole-moment surfaces. 
    more » « less
  4. We report an advanced Fourier transform spectrometer (FTS) on silicon with significant improvement compared with our previous demonstration in [Nat. Commun.9,665(2018)2041-1723]. We retrieve a broadband spectrum (7 THz around 193 THz) with 0.11 THz or sub nm resolution, more than 3 times higher than previously demonstrated [Nat. Commun.9,665(2018)2041-1723]. Moreover, it effectively solves the issue of fabrication variation in waveguide width, which is a common issue in silicon photonics. The structure is a balanced Mach–Zehnder interferometer with 10 cm long serpentine waveguides. Quasi-continuous optical path difference between the two arms is induced by changing the effective index of one arm using an integrated heater. The serpentine arms utilize wide multi-mode waveguides at the straight sections to reduce propagation loss and narrow single-mode waveguides at the bending sections to keep the footprint compact and avoid modal crosstalk. The reduction of propagation loss leads to higher spectral efficiency, larger dynamic range, and better signal-to-noise ratio. Also, for the first time to our knowledge, we perform a thorough systematic analysis on how the fabrication variation on the waveguide widths can affect its performance. Additionally, we demonstrate that using wide waveguides efficiently leads to a fabrication-tolerant device. This work could further pave the way towards a mature silicon-based FTS operating with both broad bandwidth (over 60 nm) and high resolution suitable for integration with various mobile platforms. 
    more » « less
  5. Abstract We present an ultra-compact single-shot spectrometer on silicon platform for sparse spectrum reconstruction. It consists of 32 stratified waveguide filters (SWFs) with diverse transmission spectra for sampling the unknown spectrum of the input signal and a specially designed ultra-compact structure for splitting the incident signal into those 32 filters with low power imbalance. Each SWF has a footprint less than 1 µm × 30 µm, while the 1 × 32 splitter and 32 filters in total occupy an area of about 35 µm × 260 µm, which to the best of our knowledge, is the smallest footprint spectrometer realized on silicon photonic platform. Experimental characteristics of the fabricated spectrometer demonstrate a broad operating bandwidth of 180 nm centered at 1550 nm and narrowband peaks with 0.45 nm Full-Width-Half-Maximum (FWHM) can be clearly resolved. This concept can also be implemented using other material platforms for operation in optical spectral bands of interest for various applications. 
    more » « less