We can define Photonics as the set of technologies that use light as an element to generate all applications of all kinds. This is a fundamental technology for modern life and economic growth, which has enabled other key technologies (such as, for example, advanced high-precision manufacturing). It has revolutionised diagnostic tools and medical treatment (image diagnosis, clinical analyses, genetic sequencing, advanced surgery, etc.). It has contributed to transforming the energy outlook by impacting technologies relating to the generation and use of energy (solar energy, efficient lighting, etc.). It has also enabled us to have communication networks without which the internet would not exist today. In the near future, photonics will become a key technology in the diagnosis and treatment of diseases and in the development of new sources of clean energy such as fusion energy. It may play a crucial role in information storage demands and calculation capacity or in smart agriculture.
In this present and future scenario, photonics is consolidated one of the technologies that could have the greatest potential impact on society in coming decades, in economic terms and in terms of the population’s welfare. For this reason, the European Union has identified it as one of the Key Enabling Technologies in the Horizon 2020 and Horizon Europe programmes, and the Catalan Government has incorporated it as a facilitating technology in the RIS3CAT strategy.
For over 40 years, the UPC Terrassa Campus has constituted a notable centre in the area of photonics, bringing together various agents who play highly complementary roles. The UPC provides training through the Terrassa Faculty of Optics and Optometry and the Engineering School. It undertakes basic research in photonics via several groups (DONLL, GREO, etc.) and supports photonic technology transfer to industry through applied research developed in CD6. It has also promoted entrepreneurship with the creation of up to 12 new technology-based companies.
The application of technological solutions to social problems or to the development of new services is usually channelled through mechanisms of knowledge transfer to companies. One of the fields in which the impact is most evident is the area of medicine. CD6 has formed solid collaborations with several national and international hospital institutions. These collaborations enable the identification of needs by medical professionals and the joint promotion of technology development projects that seek to provide light-based solutions (photonics). CD6 has contributed successfully to two areas: improving medical diagnosis through spectral image technology and the diagnosis of eye disorders.
Improvement in medical diagnosis through spectral image technology
Spectral or multispectral imaging technology has been revealed in recent years as a tool of great potential for improving medical diagnosis. This science combines the benefits of conventional imaging technology with traditional spectroscopy. That is, each pixel of a sensor obtains spectral information on the sample under analysis, and not only about the colour, as is the case with most conventional digital cameras. This information could be a lot more suitable than colour for many applications, as the spectroscopic properties such as reflectance or transmittance depend, to a great extent, on the chemical properties of the material that is being analysed. Therefore, this technology enables a spectral analysis with spatial resolution (point to point) in contrast to conventional spectrophotometry, so that samples can be studied that are not uniform. In addition, samples are studied in a non-destructive way, with minimum, rapid preparation.
A set of spectral images (or spectral cube) is obtained from the acquisition of sample images through many more channels than the three that are traditionally used, that is, red, green and blue (RGB). The register of the channels or spectral bands can be achieved by illuminating the sample with a source of light from a broad emission spectrum, that is, white, and filtering the light in narrow bands throughout the spectral range of interest (through different band-pass filters or using a tunable filter), or by including a spectrograph (in pushbroom types of lineal exploration systems). More recently, configurations have been applied in which LED (light emitting diode) light sources are used to directly illuminate the sample in narrow spectral bands, which simplifies the design and reduces the cost of the systems.
Using this technology, improvements have been made in the diagnosis of skin cancer, and a new generation of retinographs, devices used to study the retina, have been developed. In addition, advances have been made in the diagnosis of haematological diseases the affect red blood cells. In this last case, alterations in red blood cells can cause very severe blood disorders if they are not diagnosed in time. In the child population, it is crucial to diagnose them at an early stage.
Diagnosis of eye disorders
Vision plays a crucial role in the relation between humans and their environment, as it provides around 75% of the information that we receive. Therefore, disorders relating to the visual system have a high impact on people’s quality of life. The wide range of eye disorders or diseases range from refractive errors of the eye (myopia, hypermetropia and astigmatism) to eye diseases that can cause total or partial blindness (macular degeneration, glaucoma, etc.), malformations or degeneration of the cornea or crystalline lens (keratoconus, cataracts, etc.) and changes to the oculomotor system. An effective, early diagnosis of these disorders can help to determine and guide the most suitable treatment in each case, with the consequent social (increase in patient wellbeing) and economic (health system savings) benefits.
In this aspect, photonics plays a key role. Light has historically been a basic tool for vision professionals, given the relation between light and the visual system. However, in recent years, due to the revolution in photonics-based techniques, the contribution of optical techniques to improving the diagnosis and treatment of eye disorders has increased. Such techniques have made it possible to obtain information on the morphology and functionality of the eye in an objective, non-invasive way.
Experience in this area has led recently to new lines of work. For example, instruments have been developed to measure tear stability based on degradation of the corneal reflex. New ocular imaging techniques have been developed or perfected and techniques have been developed that are aimed at the objective, automatic assessment of visual function through virtual reality systems and their application to the area of eye disorders.
Agriculture, livestock and fishing are sectors of activity that have existed for thousands of years. From a technological perspective, they have evolved to meet the growing demand for basic foodstuffs. Technological innovations have not only been focused on increasing the productivity and quality of the final product, but also on minimising the environmental impact of these activities on a large scale. In this area, photonics plays a decisive role.
One example is pest control. In the last 100 years, pest control has been carried out using pesticides. The new regulations try to minimise pesticide use as, on some occasions, they can have negative impacts on the environment and on food security. The chemical industry has modified the pest control strategy using systems based on insect pheromones. Pheromones are chemical substances that are secreted to facilitate mating in reproductive periods and are specific to each species. The pest control strategy involves accurately monitoring the number of individuals of a certain species that are present in the field. Once a certain value has been attained, pheromones are applied that can act in two ways: preventing males and females from finding each other (confusion) or depositing the pheromone in traps where males are captured (Attract & Kill).
In this process, photonics enables the count of the number of individuals to be carried out automatically with high precision. The current method is based on manual counting of specimens in traps that could contain thousands of individuals, which tend to be mixed with insects of other species. The efficacy of controlling pests with pheromones depends strongly on the quality of these counts. Photonics solutions enable the identification and counting of individuals of a specific species.
Numerous applications exist in this field. For example, grape vines can be monitored using multispectral sensors mounted on drones. These enable the state of the vines to be assessed and a forecast made of the quality and quantity of production, or the measure of nitrates and phosphates in the soil. This helps to make a sustainable use of fertilisers.