Building Otto: An open-source Franz diffusion cell autosampler for automating in vitro skin permeation studies

Area of Science:

• Pharmacokinetics and Drug Delivery
• Biomedical Engineering
• Laboratory Automation

Background:

• Manual operation of Franz diffusion cells (FDCs) for skin drug absorption studies is labor-intensive, time-consuming, and prone to human error and variability.
• Automating FDCs is challenging due to the high cost and proprietary nature of existing commercial solutions.
• The need for continuous sampling in FDC studies presents logistical difficulties for researchers.

Purpose of the Study:

• To develop a customizable, affordable, and open-source aftermarket automation solution for retrofitting existing Franz diffusion cells.
• To address the limitations of manual FDC operation and costly commercial automation systems.
• To enhance the efficiency and reliability of drug absorption studies using automated sampling.

Main Methods:

• Developed 'Otto', an FDC automation system using a modified Cartesian 3D printer as a gantry and 3D-printed components for liquid handling.
• Integrated common and inexpensive laboratory consumables, including standard autosampler vials for sample collection.
• Designed 'OttoMate', a companion software with a graphical user interface for programming Otto, generating human-readable code.

Main Results:

• Otto is a retrofittable FDC autosampler capable of handling 100 samples per run, supporting high-throughput analysis.
• The system integrates with existing FDCs and downstream analytical equipment without requiring modifications.
• Demonstrated the design, construction, operation, and characterization of the Otto system.

Conclusions:

• Otto represents the first open-source, retrofittable FDC autosampler with high sample throughput.
• This affordable automation solution overcomes the challenges of manual operation and expensive commercial alternatives.
• Otto enhances the efficiency and reproducibility of drug absorption research through automated sampling.