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A wafer level liquid cavity integrated amperometric gas sensor with ppb leve nitric oxide gas sensitivity
KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
KTH, School of Electrical Engineering (EES), Micro and Nanosystems.ORCID iD: 0000-0001-9552-4234
KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
(English)Article in journal (Refereed) In press
Abstract [en]

A miniaturized amperometric nitric oxide (NO) gas sensor based on wafer-level fabrication of electrodes and a liquid electrolyte chamber is reported in this paper. The sensor is able to detect NO gas concentrations of the order of parts per billion (ppb) levels and has a measured sensitivity of 0.04 nA ppb−1 with a response time of approximately 12 s. A sufficiently high selectivity of the sensor to interfering gases such as carbon monoxide (CO) and to ammonia (NH3) makes it potentially relevant for monitoring of asthma. In addition, the sensor was characterized for electrolyte evaporation which indicated a sensor operation lifetime allowing approximately 200 measurements.

Keyword [en]
nitric oxide, amperometric, gas sensor, MEMS, silicon, Nafion
National Category
Engineering and Technology
URN: urn:nbn:se:kth:diva-172968OAI: diva2:851087

QP 201509

Available from: 2015-09-03 Created: 2015-09-03 Last updated: 2015-09-07Bibliographically approved
In thesis
1. MEMS-based electrochemical gas sensors and wafer-level methods
Open this publication in new window or tab >>MEMS-based electrochemical gas sensors and wafer-level methods
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis describes novel microel ectromechanical system (MEMS) based electrochemical gas sensors and methods of fabrication.

This thesis presents the research in two parts. In the first part, a method to handle a thin silicon wafer using an electrochemically active adhesive is described. Handling of a thin silicon wafer is an important issue in 3D-IC manufacturing where through silicon vias (TSVs) is an enabling technology. Thin silicon wafers are flexible and fragile, therefore difficult to handle. In addressing the need for a reliable solution, a method based on an electrochemically active adhesive was developed. In this method, an electrochemically active adhesive was diluted and spin coated on a 100 mm diameter silicon wafer (carrier wafer) on which another silicon wafer (device wafer) was bonded. Device wafer was subjected to post processing fabrication technique such as wafer thinning. Successful debonding of the device wafer was achieved by applying a voltage between the two wafers. In another part of the research, a fabrication process for developing a functional nanoporous material using atomic layer deposition is presented. In order to realize a nanoporous electrode, a nanoporous anodized aluminum oxide (AAO) substrate was used, which was functionalized with very thin layers (~ 10 nm) of platinum (Pt) and aluminum oxide (Al2O3) using atomic layer deposition. Nanoporous material when used as an electrode delivers high sensitivity due to the inherent high surface area and is potentially applicable in fuel cells and in electrochemical sensing.

The second part of the thesis addresses the need for a high performance gas sensor that is applicable for asthma monitoring. Asthma is a disease related to the inflammation in the airways of the lungs and is characterized by the presence of nitric oxide gas in the exhaled breath. The gas concentration of above approximately 50 parts-per-billion indicates a likely presence of asthma. A MEMS based electrochemical gas sensor was successfully designed and developed to meet the stringent requirements needed for asthma detection. Furthermore, to enable a hand held asthma measuring instrument, a miniaturized sensor with integrated electrodes and liquid electrolyte was developed. The electrodes were assembled at a wafer-level to demonstrate the feasibility towards a high volume fabrication of the gas sensors. In addition, the designed amperometric gas sensor was successfully tested for hydrogen sulphide concentration, which is a bio marker for bad breath.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. xiv, 77 p.
TRITA-EE, ISSN 1653-5146 ; 2015:030
MEMS, gas sensors, electrochemical, nitric oxide, hydrogen sulphide, nafion, nano
National Category
Engineering and Technology
urn:nbn:se:kth:diva-172955 (URN)978-91-7595-661-9 (ISBN)
Public defence
2015-10-02, Q2, Osquldas väg 10,, Stockholm, 10:00 (English)
EU, European Research Council, 267528VINNOVASwedish Research Council

QC 20150907

Available from: 2015-09-07 Created: 2015-09-03 Last updated: 2015-09-07Bibliographically approved

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