PIRMAH: Photoacoustic Infrared Microscope for Automated Histopathology

Infrared microscopy is a method of choice for label free mapping of biomarkers leading to automated histopathology. However, infrared microscopy image acquisition speed is slow and offers limited spatial resolution. PIRMAH addresses these limitations by using a photoacoustic method for video rate mid-infrared (2-12μm) 2-D spectro-imaging and 3-D tomography. PIRMAH leads to commercialization of an ex-vivo microscope for automated histopathology and its miniaturization for endoscopic applications.

The overall project goal was to develop a photoacoustic infrared microscope (PIM) prototype that overcomes the limitations of conventional Fourier-transform infrared (FT-IR) microscopy, and will allow extemporaneous ex-vivo and in-vivo automated histopathology:

– High speed-video-rate image acquisition speed (up to 10 MHz infrared frequency-pixel acquisition rate)

– Sub-wavelength spatial resolution (down to 1 μm) to achieve a higher contrast of cellular substructures

– 3-D depth profiling (tomography).

– Compatible with the dimension constrains of endoscopic applications

Art photonics provided the high-quality polycrystalline (PIR) and chalcogenide (CIR) glass and fibers for  transmitting in the mid Infrared region.

Manufacturing methods was adapted to achieve cost effective and mass production of disposable PIM optical heads. In details, to fit the PIRMAH device, the IR fibres distal end was served as diffraction limited point source. The mechanical properties (stiffness, resistance to repeated deformation) and diameter, were met the PIRMAH fiber scanner constrains.

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