Non-optical, label-free electrical capacitance imaging of microorganisms

Area of Science:

• Microbiology
• Biophysics
• Sensor Technology

Background:

• Optical microscopy is a cornerstone of microbiology but requires extensive sample preparation, limiting its application.
• Existing non-optical methods are often destructive or equipment-intensive.
• There is a need for accessible, non-invasive imaging techniques for diverse microbial studies.

Purpose of the Study:

• To introduce electrical capacitance imaging (ECI) as a non-optical, label-free method for live microbial imaging.
• To demonstrate ECI's capability for spatial and temporal resolution in microbial communities.
• To establish ECI as a versatile, low-cost imaging platform.

Main Methods:

• Utilized a semiconductor sensor array for localized capacitance measurements of microbial samples.
• Generated textured images based on capacitance data.
• Correlated ECI data with 3D confocal microscopy for validation.
• Performed week-long time-lapse experiments to observe biofilm development.

Main Results:

• Successfully generated textured images of various microbial colonies using ECI.
• Demonstrated that capacitance correlates with local sample thickness.
• Showcased the ability to distinguish between microbial species in co-culture.
• Captured cross-sectional development of biofilms at millimeter scales over time.

Conclusions:

• ECI provides a novel, non-optical imaging solution for live microbial samples.
• The developed platform is low-cost, portable, and requires minimal sample preparation.
• ECI enables spatially and temporally resolved microbiological experiments in diverse settings.