Review of MEMS Based Fourier Transform Spectrometers

Chai, Junyu; Zhang, Kun; Liu, Wenguang; Chen, Tian; Lu, Yao; Zhao, Guangyao

doi:10.3390/mi11020214

Cited by 50 publications

(29 citation statements)

References 53 publications

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“…Bio-medical studies mostly involve samples in the condensed phase (solids and liquids) and the individual absorption bands have half-widths 5–10 cm -1 at room temperatures. This allows the use of even miniature, portable Fourier transform (FT) and/or dispersive spectrometers for spectral measurements (Ayerden et al 2014 ; Kruzelecky et al 2017 ; Chai et al 2020 ). FTIR gives highly accurate spectral data and have high sensitivity because of the multiplexing effect of total signal detection at any time, rather than single wavelength measurements as in diffraction spectrometers.…”

Section: Optical Spectroscopy Techniques For Salivamentioning

confidence: 99%

Photonics of human saliva: potential optical methods for the screening of abnormal health conditions and infections

Lukose

Mithun

et al. 2021

Biophys Rev

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Human saliva can be treated as a pool of biological markers able to reflect on the state of personal health. Recent years have witnessed an increase in the use of optical devices for the analysis of body fluids. Several groups have carried out studies investigating the potential of saliva as a non-invasive and reliable clinical specimen for use in medical diagnostics. This brief review aims to highlight the optical technologies, mainly surface plasmon resonance (SPR), Raman, and Fourier transform infrared (FTIR) spectroscopy, which are being used for the probing of saliva for diverse biomedical applications. Advances in bio photonics offer the promise of unambiguous, objective and fast detection of abnormal health conditions and viral infections (such as COVID-19) from the analysis of saliva.

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Section: Optical Spectroscopy Techniques For Salivamentioning

confidence: 99%

Photonics of human saliva: potential optical methods for the screening of abnormal health conditions and infections

Lukose

Mithun

et al. 2021

Biophys Rev

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“…Miniaturization of emission/optical spectrometers grew out of the revolution in solid state camera technologies, providing optical quantitation without sacrificing wavelength resolution for size. While most of the handheld devices were originally focused on IR and NIR measurements that include Fourier-transform (FT) spectrometers [ 64 ], a more recent focus has been on visible light [ 65 , 66 ]. The availability of fiber optics and computer generated 3-D printed components has allowed for homemade low-cost spectrometers from simple CCD cameras [ 67 , 68 , 69 ].…”

Section: Detectorsmentioning

confidence: 99%

Moving toward a Handheld “Plasma” Spectrometer for Elemental Analysis, Putting the Power of the Atom (Ion) in the Palm of Your Hand

Buckley

Doherty

2021

Molecules

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Many of the current innovations in instrument design have been focused on making them smaller, more rugged, and eventually field transportable. The ultimate application is obvious, carrying the instrument to the field for real time sample analysis without the need for a support laboratory. Real time data are priceless when screening either biological or environmental samples, as mitigation strategies can be initiated immediately upon the discovery that contaminant metals are present in a location they were not intended to be. Additionally, smaller “handheld” instruments generally require less sample for analysis, possibly increasing sensitivity, another advantage to instrument miniaturization. While many other instruments can be made smaller just by using available micro-technologies (e.g., eNose), shrinking an ICP-MS or AES to something someone might carry in a backpack or pocket is now closer to reality than in the past, and can be traced to its origins based on a component-by-component evaluation. While the optical and mass spectrometers continue to shrink in size, the ion/excitation source remains a challenge as a tradeoff exists between excitation capabilities and the power requirements for the plasma’s generation. Other supporting elements have only recently become small enough for transport. A systematic review of both where the plasma spectrometer started and the evolution of technologies currently available may provide the roadmap necessary to miniaturize the spectrometer. We identify criteria on a component-by-component basis that need to be addressed in designing a miniaturized device and recognize components (e.g., source) that probably require further optimization. For example, the excitation/ionization source must be energetic enough to take a metal from a solid state to its ionic state. Previously, a plasma required a radio frequency generator or high-power DC source, but excitation can now be accomplished with non-thermal (cold) plasma sources. Sample introduction, for solids, liquids, and gasses, presents challenges for all sources in a field instrument. Next, the interface between source and a mass detector usually requires pressure reduction techniques to get an ion from plasma to the spectrometer. Currently, plasma mass spectrometers are field ready but not necessarily handheld. Optical emission spectrometers are already capable of getting photons to the detector but could eventually be connected to your phone. Inert plasma gas generation is close to field ready if nitrogen generators can be miniaturized. Many of these components are already commercially available or at least have been reported in the literature. Comparisons to other “handheld” elemental analysis devices that employ XRF, LIBS, and electrochemical methods (and their limitations) demonstrate that a “cold” plasma-based spectrometer can be more than competitive. Migrating the cold plasma from an emission only source to a mass spectrometer source, would allow both analyte identification and potentially source apportionment through isotopic fingerprinting, and may be the last major hurdle to overcome. Finally, we offer a possible design to aid in making the cold plasma source more applicable to a field deployment.

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“…MEMS technology was also used to simplify the optical system integration of FTS; early approaches using bulk [ 5 , 6 , 33 ] and surface micromachining [ 34 ] were reported. During the last decade, monolithic integration of the interferometer optical bench into silicon was realized for a higher miniaturization and cost reduction of MEMS-based FTS, e.g., [ 35 , 36 , 37 , 38 ]. Although full on-chip integration of FT interferometers (including the translatory MOEMS) is limited to small mirror apertures and imperfect surface quality, these MEMS-FT spectrometers are starting to enter the market [ 38 ] for NIR applications and are used in cases with moderate requirements of spectral resolution due to their advantages in size and cost.…”

Section: Introductionmentioning

confidence: 99%

Wafer-Level Vacuum-Packaged Translatory MEMS Actuator with Large Stroke for NIR-FT Spectrometers

et al. 2020

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We present a wafer-level vacuum-packaged (WLVP) translatory micro-electro-mechanical system (MEMS) actuator developed for a compact near-infrared-Fourier transform spectrometer (NIR-FTS) with 800–2500 nm spectral bandwidth and signal-nose-ratio (SNR) > 1000 in the smaller bandwidth range (1200–2500 nm) for 1 s measuring time. Although monolithic, highly miniaturized MEMS NIR-FTSs exist today, we follow a classical optical FT instrumentation using a resonant MEMS mirror of 5 mm diameter with precise out-of-plane translatory oscillation for optical path-length modulation. Compared to highly miniaturized MEMS NIR-FTS, the present concept features higher optical throughput and resolution, as well as mechanical robustness and insensitivity to vibration and mechanical shock, compared to conventional FTS mirror drives. The large-stroke MEMS design uses a fully symmetrical four-pantograph suspension, avoiding problems with tilting and parasitic modes. Due to significant gas damping, a permanent vacuum of ≤3.21 Pa is required. Therefore, an MEMS design with WLVP optimization for the NIR spectral range with minimized static and dynamic mirror deformation of ≤100 nm was developed. For hermetic sealing, glass-frit bonding at elevated process temperatures of 430–440 °C was used to ensure compatibility with a qualified MEMS processes. Finally, a WLVP MEMS with a vacuum pressure of ≤0.15 Pa and Q ≥ 38,600 was realized, resulting in a stroke of 700 µm at 267 Hz for driving at 4 V in parametric resonance. The long-term stability of the 0.2 Pa interior vacuum was successfully tested using a Ne fine-leakage test and resulted in an estimated lifetime of >10 years. This meets the requirements of a compact NIR-FTS.

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Review of MEMS Based Fourier Transform Spectrometers

Cited by 50 publications

References 53 publications

Photonics of human saliva: potential optical methods for the screening of abnormal health conditions and infections

Photonics of human saliva: potential optical methods for the screening of abnormal health conditions and infections

Moving toward a Handheld “Plasma” Spectrometer for Elemental Analysis, Putting the Power of the Atom (Ion) in the Palm of Your Hand

Wafer-Level Vacuum-Packaged Translatory MEMS Actuator with Large Stroke for NIR-FT Spectrometers

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