Although skin pathologies are the fourth cause of non‐fatal disease burden worldwide, dermatological diagnostic tools used in clinical practice have seen limited evolution. Visual inspection supported by biopsy and histopathology are the standard of care, despite the existence of multiple non‐invasive imaging techniques. Epiluminescence microscopy (EM) is among the best‐adopted modalities, but is only able to provide magnified information about tissue surface. Optical coherence tomography (OCT) reveals tissue morphology with exquisite depth resolution and excellent penetration of the skin, but systems have seen limited adoption outside research settings because of shortcomings in workflow integration, reliability, affordability and size.
A team of scientist from Spain created a cost‐effective handheld, battery driven multimodal dermatologic imaging system employing a digital epiluminescent microscope and an OCT engine based on integrated optics that provides axial and lateral scanning within a volume of 30 cm3, which is the smallest OCT implementation reported to date.
3D Layout of the OCT engine within a 40‐pin butterfly package, with a total volume of 30 cm3. The different components and sub‐systems included within the package are annotated in the figure
Most current commercial OCT systems operate in the so‐called frequency‐domain, using either a broadband light source or a spectrometer, known as “spectral domain OCT” (SD OCT), or—more recently—a rapidly tunable laser, known as “swept‐source OCT” (SS OCT).
At the moment none of these commercial OCT systems is low‐cost or miniaturized. But the team demonstrated for the first time a fully integrated OCT engine based on integrated optics and a multimodal point‐of‐care skin diagnosis system based on it.
“The integration level achieved with this novel OCT engine has enabled an ultra‐compact system in a handheld format and with a weight of only 3 kg, while incorporation two additional imaging sources on top of OCT: an epiluminescence microscope in a common‐path configuration with OCT and a clinical image camera” according to team member Jose Luis Rubio-Guviernau.
Further steps towards OCT devices which can be entirely manufactured using batch and wafer‐level fabrication technologies will include monolithic photo‐detectors, hybrid assembly of light sources and fabrication of MEMS devices on the integrated photonic platform, eventually leading to an unprecedented level of compactness, cost‐reduction, functionality, reliability and manufacturing scalability for OCT imaging systems. Further integration shall also lead to a reduction on the total excess losses, therefore increasing the sensitivity‐speed trade‐off of the system.
