Localized Collection of Airborne Analytes: A Transport Driven Approach to Improve the Response Time of Existing Gas Sensor Designs

Abstract

The detection of single binding has been a recent trend in sensor research introducing various sensor designs where the active sensing elements are nanoscopic in size. Currently, transport and collection of airborne analytes for gas sensors is either diffusion based or non-localized and it becomes increasingly unlikely for analytes to interact with sensing structures where the active area is shrunk, trading an increased sensitivity with a slow response time. This report introduces a corona discharge based analyte charging method and an electrodynamic nanolens based analyte concentration concept to effectively transport airborne analytes to sensing points to improve the response time of existing gas sensor designs. Localized collection of analytes over a wide range, including microscopic particles, nanoparticles, and small molecules, is demonstrated. In all cases, the collection rate is several orders of magnitudes higher than in the case where the collection is driven by diffusion. The collection scheme is integrated on an existing SERS (surfaceenhanced Raman spectroscopy) based sensor. In terms of response time, the process is able to detect analytes at 9 ppm (parts per million) within 1 s. As a comparison, 1 h is required to reach the same signal level when diffusion-only-transport is used.

Approaching Gas Phase Electrodeposition: Process and Optimization to Enable the Self‐Aligned Growth of 3D Nanobridge‐Based Interconnects

“…[ 16 ] Others have used this technique to fabricate metallic nanostructures for surface enhanced Raman spectroscopy (SERS). [ 20,21 ] In any event, charged material continues to deposit into locations where charge dissipation can occur, leading to a growth of extended structures much like what is observed in the liquid phase based electrodeposition/plating. This report evaluates the localized growth feature of gas phase electrodeposition as a method to form self-aligned free-standing nanowire interconnects.…”

Fundamental Review to Ozone Gas Sensing Using Optical Fibre Sensors

“…Sensor requirements either in performance, physical, or cost, are application dependent [100]. Research activities on sensors in general and ozone sensors in particular, are aimed towards meeting recent sensing requirements, strengthening and upgrading some or all of the aforementioned parameters [11,12,49].…”

“…This review provides insight into vital fundamentals to gas sensing with optical fibre sensors. It is comprised of optical sensor mechanism [5], advantages of optical sensors [6,7], optical sensor classification [8], optical gas cells classification [9], Beer-Lambert law [10] and ozone gas and its research challenges [11][12][13]. Ozone is a trace gas in the atmosphere [14] and is discovered in 1839 [15].…”

Active Matrix‐Based Collection of Airborne Analytes: An Analyte Recording Chip Providing Exposure History and Finger Print

“…In other words, it becomes increasingly unlikely for an analyte molecule at low concentrations to “find” and interact with an ever increasingly small sensor, trading the gained sensitivity with a slow response time. The solution to this problem is to use a directed force to transport the analyte from a distance away to predetermined sensing points at a higher rate, which has recently been discussed elsewhere . This communication adds the ability to collect and store analytes in an active matrix array like fashion, at predetermined points on a surface, at different points in times.…”

“…The use of Coulomb forces has been chosen since localized collection of organic and inorganic nanoparticles has already been demonstrate with an unmatched sub 100 nm lateral resolution. While some sensors based on electrostatic precipitators are known, an active matrix type analyte collection chip has not yet been demonstrated. This communication reports the collection of analytes over a wide range of molecular weights including (i) microscopic particles (Kentucky blue grass pollen, 20 μm in diameter, ∼3 × 10 17 Da), (ii) inorganic nanoparticles (Cu nanoparticles, 40–60 nm in diameter, ∼3.5 × 10 8 Da; CdSeS/ZnS nanoparticles, 6 nm in diameter, ∼3.4 × 10 5 Da), all the way down to (iii) small organic molecules (MEH‐PPV, 1.5 × 10 5 –2.5 × 10 5 Da; Alq 3 , 459.43 Da; anthracene, 178.23 Da; 4‐fluorobenzenethiol 128.17 Da; benzenethiol, 110.19 Da).…”