Selective low concentration ammonia sensing in a microfluidic lab-on-a-chip

Abstract

Abstract-In the medical community, there is a considerable interest in a diagnostic breath analyzer for ammonia that is selectively enough to measure in exhaled air and small enough for the small volumes available in such an application. An indirect measurement system for low gaseous ammonia concentrations has been miniaturized and integrated on a chip in order to reach this goal. The detection limit of the system was calculated to be 1.1 parts per billion (ppb). The response time was determined to be 1.6 min with a gas flow of 50 ml/min. The required gas volume for one measurement is therefore sufficiently small, although sampling assistance is required for breath analysis. The selectivity of the system is sufficient to measure ammonia concentrations in the low-ppb range. The system is even sufficiently selective to be used in environments that contain elevated carbon dioxide levels, like exhaled air. The lower ammonia concentration expected in diagnostic breath analysis applications, 50 ppb, was demonstrated to be detectable.

Micro gas analyzers for environmental and medical applications

“…15 min may be reduced even further. The second device developed by Timmer et al was for use in breath analysis, and its performance was an improvement over that of the first device [61,62]. Selectivity of this device to NH 3 was achieved by gasification/recollection; mixing the absorbed solution with an alkaline solution and recollection of NH 3 into water.…”

An E-Nose for the Monitoring of Severe Liver Impairment: A Preliminary Study

“…For this purpose, several micro-systems were developed. One of them is described in [46]. In this work, Timmer and colleagues present a micro-fluidic system able for detecting ammonia by using a conductivity sensor.…”

A Reversible Spectrophotometric Method Based on a Coupled Microfluidic Chip for Highly Selective Ammonium Detection

“…e formed NH 3 then diffuses into the acceptor solution through the GD membrane and then followed by the spectrometric detection [10]. Previous work has utilized polypropylene (PP) [11], polydimethylsiloxane (PDMS) [12], polytetrafluoroethylene (PTFE) [13], and polyvinylidene fluoride (PVDF) [14] as the GD membranes to realize the diffusion and detection of NH 3 . ough these membranes have many similarities like hydrophobicity and gas permeability, they vary significantly in many aspects such as mechanical strength and GD efficiency.…”