Overview of the Amplifier

The Amplifier operates in association with the NeOse Advance device. While odor signals can be measured with the NeOse Advance alone if their intensity reaches a certain threshold (dependent on the VOC or mixture of VOCs tested), the Amplifier allows to improve the limit of detection of our sensors by simply connecting it to the sample inlet of the NeOse Advance. 

The Amplifier accessory improves the limit of detection of Aryballe’s device using a preconcentration step of the VOCs, and thus allows for detection of lower odor concentrations. It is based on the adsorption of volatile compounds on an adsorbent, followed by their flash release using Thermal Desorption (TD). VOCs are concentrated on the Tenax TA adsorbent (20 mg, 60-80 mesh), a resin that was chosen for its capability to detect a broad range of odors and VOCs (from C6 to C20, with a hydrophobic behavior). After a few minutes of concentration, the sample is quickly desorbed by flash heating and analyzed by the Aryballe odor sensor, coupled with a humidity and temperature sensor. Thus, a large volume of a sample can be gathered on the adsorbent, amplifying the VOC concentration before releasing it by heating.

The Amplifier is not a standalone product and requires to be associated with NeOse Advance. To automatize sample injection, an Aryballe sampler, the HeptaValve Mini can be used.

The system is operated by the Aryballe Suite for Amplifier, an application software module that executes protocols, allows for adjustment of experimental parameters and sampling automation, analyzes recorded data and provides reports. 

Amplifier accessory overview

Description

The Amplifier uses 3 male Luer Lock type fluidic inlets, one to measure the baseline, one to measure the sample after concentration and the last one used only for retrocompaptibility with previous Aryballe products. Both fluidic paths sequentially flow the air through the odor, temperature and humidity sensors. Having a separate inlet for baseline maintains a dedicated fluidic path that is as clean as possible. The Amplifier baseline inlet should always be protected by a non-sterile PTFE filter to prevent pollution from entering the Amplifier and be transferred to the NeOse Advance connected to it. 

The device requires one USB cable that should be connected to a standard USB port of the computer and is powered with a 5A 12V alimentation cable that should be connected to a wall plug. Please ensure that you are using only the charger provided by Aryballe. 

The Amplifier is compatible with other accessories such as samplers. The automated acquisition of multiple samples can be done using an external sampler (HeptaValve Mini or TriValve Mini sampling seven or three samples, respectively) that will synchronize with the Amplifier during the concentration phase.

Usage

The Amplifier can be used to collect VOCs in open environments or in laboratory settings, allowing to detect lower concentrations of odor molecules.

The underlying principle is pre-concentration of a sample by accumulation on a Tenax TA sorbent, followed by flash release at 250°C of the adsorbed molecules by thermal desorption (TD). The concentrated molecules are then transported towards the Aryballe’s odor sensor.

The Amplifier has an internal fluidic architecture that allows:

• Recording of a reference baseline (clean air for example) (inlet #2),
• Recording of a direct sample measurement, used for retro-compatibility only (inlet #3)
• Recording of a concentrated sample that was adsorbed on Tenax resin for a given period and released by thermal desorption (amplified way, inlet #4).

NeOse Advance is connected to the Amplifier outlet (1) with a standard Luer female outlet.

Internal fluidics diagram

The different modes are depicted in the figures below:

A/ Baseline recording or idle mode: Background air is taken in from inlet #2 by the NeOse Advance’s pump and then flows through the outlet #1 to NeOse Advance (odor + humidity/temperature).

B/ Concentration mode: The background gas taken in from inlet #2 by the device’s pump flows through the outlet #1 to the NeOse Advance (so that the baseline can be recorded), while the Amplifier's pump generates a flow from inlet #4 (connected to the sample to be tested) to the sorbent trap (shown as TD). The volume of sample collected depends on concentration time and air flow. 

C/ Blind purge: before making a thermo-desorption measure, the purge allows to clean-up the dead volume and make sure that there is no sample pollution remaining on any fluidic line.

D/ Thermo-desorption mode: The sample collected on the TD trap during the concentration phase is thermally desorbed from the Tenax TA sorbent at a temperature of 250°C. When the temperature is reached, the valve V3 switches to direct the desorbed sample towards the outlet #1 so that the concentrated sample can be analyzed. 

E/ Post-Experiment Clean-up: The TD trap is warmed up to 275°C so that it can release any trapped compound not desorbed during the thermo-desportion phase. 

Warning and safety

For the operator's safety, three thresholds have been defined that can trigger events, which will appear as tags (also visible in Live Data View) and in the Amplifier reports since having this information for post-analysis can be helpful to interpret:

• TD heating is taking too much time
• Detected temperature is too high
• The temperature sensor is not responding properly (out of the targeted temperature value)

Above this firmware and software security, a thermo-fuse is embedded close to the hot point and will cut the power circuit if an overheat occurs.

Preparing your experiment

Fluidic installation

To install the whole set-up, please refer to the Aryballe Suite User Manual. 

Validating system cleanliness

To perform system cleanliness check, please refer to the Aryballe Suite User Manual. 

Launching an experiment

General information about amplified acquisition

Type of protocols

Several acquisition protocols can be launched from the home page of the Runner Launcher:

Steps during acquisition

Every aforementioned protocol is following the same steps. “x” is a reference to variables that can be adjusted by the operator.

1. A first phase makes sure that the thermal desorption trap is cooled down to 35°C.
2. A concentration phase of x minutes follows, at an 80 mL/min air flow. VOCs are progressively trapped onto the Tenax resin.
3. A purge phase of x seconds allows the system to clean internal tubing of remaining VOCs that were not adsorbed on the sorbent. This requires the sample to be removed, either manually or automatically if using a HeptaValve Mini.
4. The sensor records a reference signal from the “Baseline” way as a background measurement for 5 seconds.
5. The Thermo-Desorption trap is heated up to x°C so that it flash releases VOCs.
6. Once the temperature is reached, the fluidic system directs the gas flow from the trap to the NeOse Advance for x seconds.
7. The trap is then cleaned by flushing external air at a temperature and during a time previously set by the operator.

Note: Upon hover over a field, a brief description will be displayed.

System shutdown

Cleaning

After each measurement session, tubing must be cleaned:

• During a measurement session, the Post-Experiment Clean-up should be sufficient to clean your Amplifier. To make sure your Amplifier is clean, refer to section “Check Amplifier cleanliness”.
• Refer to the NeOse Advance User Manual for cleanup and shut down procedure.

Shutdown

When the device is clean, shut down the system:

1. Close the Application window.
2. Close (if opened) the Live data view and Annotator view windows in the browser.
3. Unplug your device (and, if any, the HeptaValve Mini), as described in the relevant User Manual shutdown procedure.
4. Unplug the power source (12V 5A Jack) before removing the USB plug from the Amplifier.
5. Remove the PTFE filter from the baseline inlets. 
6. Place back all translucent caps onto the Luer inlets to prevent dust entering and polluting the system during storage.