Accession Number : ADA602499


Title :   MEMS Cantilever Sensor for THz Photoacoustic Chemical Sensing and Spectroscopy


Descriptive Note : Doctoral thesis


Corporate Author : AIR FORCE INSTITUTE OF TECHNOLOGY WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT


Personal Author(s) : Glauvitz, Nathan E


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a602499.pdf


Report Date : 26 Dec 2013


Pagination or Media Count : 217


Abstract : Sensitive Microelectromechanical System (MEMS) cantilever designs were modeled, fabricated, and tested to measure the photoacoustic (PA) response of gasses to terahertz (THz) radiation. Surface and bulk micromachining technologies were employed to create the extremely sensitive devices that could detect very small changes in pressure. Fabricated devices were then tested in a custom made THz PA vacuum test chamber where the cantilever deflections caused by the photoacoustic effect were measured with a laser interferometer and iris beam clipped methods. The sensitive cantilever designs achieved a normalized noise equivalent absorption coefficient of 2.83x10(-10) cm(-1) W Hz(-1/2) using a 25 (micro)W radiation source power and a 1 s sampling time. Traditional gas phase molecular spectroscopy absorption cells are large and bulky. The outcome of this research resulted was a photoacoustic detection method that was virtually independent of the absorption path-length, which allowed the chamber dimensions to be greatly reduced, leading to the possibility of a compact, portable chemical detection and spectroscopy system.


Descriptors :   *DETECTORS , *MICROELECTROMECHANICAL SYSTEMS , *SPECTROSCOPY , ABSORPTION , ABSORPTION COEFFICIENTS , CANTILEVER BEAMS , CHAMBERS , CHEMICAL DETECTION , DEFLECTION , FABRICATION , IRIS , LASERS , MEASUREMENT , MICROMACHINING , NOISE , OPTICAL INTERFEROMETERS , PORTABLE EQUIPMENT , POWER SUPPLIES , PRESSURE , RADIATION , RESPONSE , SENSITIVITY , SURFACES , TEST FACILITIES , THESES , VACUUM CHAMBERS


Subject Categories : Electrical and Electronic Equipment
      Atomic and Molecular Physics and Spectroscopy


Distribution Statement : APPROVED FOR PUBLIC RELEASE