National Research Council Italy creates fully integrated optofluidic platform

10 Apr 2025

Laser fabrication allows microfluidic chip to be reconfigured for different cytometry operations.

A project at Italy's National Research Council (Consiglio Nazionale delle Ricerche, CNR) has developed an integrated optofluidic platform suitable for high-resolution imaging flow cytometry (IFC).

Described in Nature Scientific Reports, the device exploits current advances in laser manufacturing to create and align its photonic and optofluidic components.

The study aimed in particular to address potential improvements in current IFC operations. IFC is a variant of flow cytometry intended to combine that technique's inherent high throughput with the ability for single cell image acquisition via microscopy.

Conventional flow cytometry involves biological cells tagged with fluorescent markers being illuminated while passing along a channel narrow enough to force the cells into roughly single file. Analysis of the light emitted can reveal information about individual cell size, DNA content and other parameters.

IFC merges the fluidic system of a flow cytometer with advanced camera technology, potentially capturing multiple fluorescent images at high rates per second and allowing morphological analysis of cell populations at a high-throughput scale.

"In recent years IFC is gaining increasing attention as it combines the characteristics of conventional flow cytometry with optical microscopy techniques," commented the CNR project in its paper.

"However, current 3D IFC systems are often limited by incompatibility with available microfluidic devices, or by instrumental complexity that might lead to optical misalignment or mechanical instabilities in day-by-day operation. IFC systems are also typically more expensive and resource-intensive than conventional flow cytometers."

Drug screening and personalized therapy

CNR aimed to tackle these issues through manufacture of an integrated miniaturized platform encompassing all the optical and the fluidic delivery elements, by bonding an aluminoborosilcate glass photonic chip to an optofluidic chip made from fused silica glass. Both components were fabricated by femtosecond laser irradiation followed by chemical etching, or FLICE.

Adjustment of the laser parameters gave CNR control over factors such as local refractive index modification and the material's sensitivity to subsequent etching, so that optical waveguides and buried microchannels can ultimately be created in the structure via the one fabrication technique and a single optical setup.

The end result is a fully integrated optofluidic platform in which the borosilicate glass chip contains reconfigurable integrated photonic circuits needed for patterned light generation, and the fused silica glass chip incorporates cylindrical hollow lenses for light-sheet illumination.

Trials using HeLa cells showed that the team's proof-of-concept device could image 40 cells per minute, each sectioned into 15 planes via light-sheet microscopy. Although this is at present considerably lower throughput than commercial IFC platforms, those instruments allow only two-dimensional analysis at standard or low resolution, and CNR expects improvements to its platform will improve the imaging rate substantially.

"The promising results achieved in the bio validation open the way to the use of such a device for large cell population phenotyping or drugs screening for personalized therapies evaluation," said the project.