eTop: Puff Topography Instrument

eTop puff topography instrument setup for inhalation measurement

eTop puff topography instrument developed to monitor how users puff tobacco and nicotine devices during real-world use.

Overview of the eTop Puff Topography Instrument

eTop (electronic cigarette puff topography instrument) is a compact research device designed to measure and record puffing behavior across a range of tobacco and nicotine products, including cigarettes, electronic cigarettes, heated tobacco products (HTPs), and waterpipes. The system captures real-time inhalation topography parameters such as puff flow rate, puff duration, puff volume, and interpuff interval during controlled sessions.

Rather than relying on assumed usage patterns, eTop quantifies how products are actually used under experimental conditions. The instrument records high-resolution flow and timing data and generates structured outputs that can be directly integrated into quantitative analyses without extensive post-processing.

Since its introduction, eTop has supported both exploratory and standardized studies, enabling detailed characterization of user behavior and contributing to studies of nicotine delivery and exposure.

eTop was developed at the Aerosol Research Lab at the American University of Beirut (AUB) and has been used in collaborative research examining inhalation topography and exposure-related outcomes.

Puff Measurement Methodology

eTop quantifies inhalation topography using a calibrated flow measurement assembly integrated within a mouthpiece-based interface. The system captures real-time airflow data during each inhalation and converts it to volumetric flow rate through established calibration procedures.

Puff events are identified using predefined flow thresholds, enabling calculation of puff duration, peak flow rate, interpuff interval, and puff volume. Puff volume is derived by integrating the measured flow signal over the duration of each inhalation.

The measurement assembly remains fixed and calibrated across experiments, while interchangeable mouthpieces and flexible adapters allow compatibility with a wide range of tobacco and nicotine product designs without altering the core measurement system.

Key Measurement Outputs

eTop provides multi-level inhalation topography data, including continuous real-time flow recordings as well as structured per-puff and session-level outputs.

The system records:

  • Continuous time-series airflow data for the entire session
  • Automated puff detection and segmentation
  • Per-puff metrics including puff duration, puff volume, peak flow rate, mean flow rate, and interpuff interval
  • Total puff count and session duration
  • Aggregate session metrics such as cumulative inhaled volume

Raw time-series data can be exported for waveform analysis, while derived puff parameters are available for immediate statistical processing.

In addition to airflow-based topography parameters, eTop incorporates a secondary sensing channel to quantify inhalation resistance during use. This allows simultaneous assessment of user effort and product draw characteristics, providing additional insight into device performance and user-product interaction.

Technical Specifications

Sampling Performance

  • Sampling rate: 100 Hz
  • Continuous real-time data acquisition

Flow Measurement Range

  • Approximate operating range: 0.15 – 15 L/min
    (compatible with cigarette, ECIG, heated tobacco, and waterpipe regimes)

Measured Parameters

  • Puff duration
  • Puff volume
  • Peak and mean flow rate
  • Interpuff interval
  • Session-level aggregate metrics

Power Requirements

  • USB-powered during standard operation
  • 12 V external supply used for calibration procedures

Physical Dimensions

  • Instrument enclosure: 6.3 in × 4.1 in × 2.1 in
  • External computer required for data recording and analysis

Research Use Cases & Study Workflow

eTop was developed for sustained laboratory research use, prioritizing measurement consistency across studies and product categories. The instrument enables standardized quantification of puff topography without requiring hardware modification for different tobacco or nicotine devices, as adaptation occurs through interchangeable interfaces and calibration procedures.

In controlled laboratory settings, eTop is used to characterize puff duration, puff volume, flow rate, inhalation patterns, and exposure-relevant behavior across cigarettes, electronic cigarettes, heated tobacco products, and waterpipes. These measurements support investigations of nicotine delivery, user compensation, device design effects, and behavioral variability.

Recorded sessions can be exported and replayed on smoking machines, allowing authentic user puffing profiles to be reproduced under controlled conditions. This capability supports emissions testing, toxicant analysis, and standardized exposure assessment protocols.

Publications and Validation

The eTop puff topography instrument has been used in several peer-reviewed research studies to quantify human puffing behavior in electronic cigarette (ECIG) use. In Felicione et al. (2020), eTop’s performance was directly compared to a video-based method, demonstrating accurate measurement of puff duration, flow rate, and other topography parameters. In Spindle et al. (2015), mouthpiece-based computerized systems such as eTop were used to examine ECIG users’ puffing behavior and to assess how measurement hardware might influence nicotine delivery and subjective effects. In Ferdous et al. (2024), the mouthpiece-connected topography recorder was applied to investigate changes in puffing behavior with partial nicotine reduction.

  • Felicione NJ, Karaoghlanian N, Shihadeh A, Eissenberg T, Blank MD (2020). Comparison of Measurement Methods for Electronic Cigarette Puff Topography. Link
  • Spindle TR, Breland AB, Karaoghlanian NV, Shihadeh AL, Eissenberg T (2015). Preliminary Results of an Examination of Electronic Cigarette User Puff Topography. Link
  • Ferdous T, et al. (2024). Partial Nicotine Reduction and E-Cigarette Users’ Puffing Behavior Using Mouthpiece-Connected Topography Recording Device. Link

Institutional Adoption

eTop has been adopted by multiple research groups internationally and remains in active use across different study designs and laboratory environments.

The map below shows current universities and research groups using the instrument.