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The resolution achievable with conventional optical microscopes is limited because of the physical laws governing the wavelength of light. This means they cannot be used to directly observe single proteins, DNA molecules or inside living cells. At the moment, only indirect observation – meaning the interpretation of measured data – is possible with complex, expensive and bulky electron microscopes. However, such devices are not suitable for observing delicate living tissues.
Super-resolution microscopes currently in use are based on bulky optical systems and require complex preparations of the samples being observed.
To overcome these limitations, the EU-funded CHIPSCOPE project is developing a chip-sized microscope that uses arrays of light-emitting diodes (LEDs) smaller in diameter than a human hair to illuminate the object being observed. The resulting device combines simplicity, ease of operation and affordability.
The new technology could advance research in areas that currently use optical microscopes – particularly medicine. It will help researchers in the field without access to laboratories or other scientific infrastructure to use the device to make microscopic images easily. Furthermore, because the technology is cheaper it will be accessible to researchers in developing countries.
These microscopes-in-a-chip could also be integrated into consumer electronic products, in the same way cameras are built into smartphones today. The sample is placed on to the LEDs and underneath a photodetector which captures the signals emitted by the arrays. Contrary to conventional microscopy, spatial resolution is provided by the LEDs rather than by the optical detection system. Hence, this system does not require particular alignments or complex focusing systems.
The LEDs can be switched on and off individually, at high speed, allowing cells to be observed in real time, capturing up to 10 frames per second. The project is developing software to enable the easy control of light pattern, brightness and modulation frequency. Advanced 3D nanodevice fabrication methods are used to manufacture the LED array.
The first version of the CHIPSCOPE microscope was assembled in December 2018. The project team intends to prove the value of the microscope by studying the development in living tissue of Idiopathic Pulmonary Fibrosis, a chronic age-related lung disease that kills 500 000 people worldwide each year.