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Project Breakdown

Developing New Laser Sources for Deep Tissue Penetration

The core concept of Amplitude is that imaging systems with access to the 1650-1800nm wavelength range (3rd biological window) will be able to see deeper into tissue than is currently possible. However, there are  few commercial lasers that can operate within this window, and most are very large and expensive, which limits their use in commercial imaging systems. Amplitude has developed new compact and affordable ultrashort pulsed fibre lasers, which cover the wavelength range from 1650nm to 1800nm, as a robust and effective solution for powering commercial microscopes and endoscopes

The project has prototyped two lasers: 

 

  1. A MOPA system, based on nonlinear Raman effect in optical fibre, which operates at 1675nm. This laser has  been frequency doubled using a unique Second Harmonic Generation (SHG) mixer developed for the project by HCP Photonics, which gives it an additional mode (835nm)  enabling autofluorescence imaging, without the need for an additional laser, ensuring efficiency at the deepest design level. View the laser data sheet here.

  2. A Tm-doped system with extended tunability range covering the 1700-1900nm wavelength range and within target parameters. 

 

The MOPA laser is now being used by our technology development partners as the engine for the Amplitude microscope and endoscopic probe.

 

The TM-doped laser is currently under test at ICFO, Spain, and will be used to investigate the possibilities and limitations of imaging within the 3rd biological window. 

Developing Imaging Systems Suitable for the Clinic

The primary goal of Amplitude is to prototype and validate a microscope, and endoscopic probe, that can perform multi modal imaging in a clinical setting. Packaging the components together into these microscope/endoscope devices requires substantial effort.

To optimise any generated nonlinear signal, care must be taken during packaging about the pulse dispersion caused by the bulky optics, such as the high Numerical Aperture (NA) objectives in the microscope. Furthermore, the necessary dichroic mirrors and colour filters do not currently exist and will need to be custom made for this specific wavelength range. Task specific analysis software functions will also need to be integrated into the main software platform to enable simple comparison with histological images and a provide better visualization.

Extension of the microscope into the endoscope will also require a unique probe design. Broadband and single mode channels will carry different wavelengths, and as an endoscopic probe has much greater dispersion than a simple microscope objective, dispersion compensation units will be tailored for endoscopic deliver.

Testing Imaging Devices in the Clinic

The Amplitude microscope will also be validated and evaluated during the project, on clinical samples from patients undergoing surgery to treat bladder cancer. Samples from 100 consecutive consenting patients will be analysed label-free by the Amplitude microscope, before being sent on for definitive histopathological analysis, the current gold standard for diagnosis. By comparing Amplitude’s results to the current gold standard for bladder cancer, patterns can be identified, and thus the best options for patients determined, eventually in a much faster way.

The Amplitude endoscope testing will be more challenging. Unlike the microscope, which can be validated using ex vivo samples, the endoscope must be tested in vivo. Thus, a smaller scale of 10 consecutive consenting patients undergoing cystoscopy will provide early proof of concept. Results from this small cohort can be compared to traditional microscopy images, as well as the images from the Amplitude microscope. As a medical device, complete endoscope validation must take time well beyond the Amplitude project duration, but essential initial demonstrations will be completed during the Amplitude project.

Identifying New Biomarkers for Bladder Cancer

Amplitude also aims to improve the identification and diagnosis of tumour tissues through fast, label-free optical methods. Developing reliable biological models is the key to identify and characterise tumour biomarkers for such methods. To achieve this, pre-clinical in vitro 3D models from bladder cancer cell lines with various grade of aggressiveness/invasiveness are being generated by Amplitude to enable new insights on bladder cancer biology and behaviour.

With the assistance of the new Amplitude laser sources, these 3D models will be examined through two label-free optical techniques: Raman spectroscopy and autofluorescence imaging, detecting relevant bladder cancer biomarkers. Once the models have revealed which biomarkers to look for, fresh ex vivo tumour biopsies from patients will be tested, ensuring clinical translation of results.

Finally, using advanced AI supervised learning techniques, images of patient tumours will be analysed to identify tumour features relevant for diagnosis. By doing so, Amplitude can develop automated classification algorithms for tumour discrimination, improving bladder cancer diagnosis further still.

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