18 February 2019
Professors Chen Shih-chi (right) and Christopher Leung Kai-shun co-developed the world's first DH-TPE microscope. Photo: EJ Insight
Professors Chen Shih-chi (right) and Christopher Leung Kai-shun co-developed the world's first DH-TPE microscope. Photo: EJ Insight

CUHK unveils world’s first ‘ultrafast’ 3D microscope

The Chinese University of Hong Kong has developed the world’s first “ultrafast” 3D microscope that can be used in studying eye and neurological diseases like glaucoma and Alzheimer’s disease.

Professor Chen Shih-chi, from the Department of Mechanical and Automation Engineering, said a prototype of the device was successfully developed earlier this month.

It mainly involved the application of digital micromirror device (DMD) technology, which is used in ordinary projectors, to traditional Two-Photon Excitation (TPE) microscopes. DMD chips vastly enhance the speed of imaging and make 3D microscopic images possible.

The high-speed and 3D imaging opens the possibility of producing videos that trace in real time the subtle neural degeneration in glaucoma and other eye or neurological diseases.

The enhanced digital holography-based TPE (DH-TPE) microscope can locate 20 focal points instead of just one in conventional ones.

The DH-TPE microscope can also make 32,000 images per second on different depths of the object, compared with 100 using the traditional microscope.

The new device also has interactive features that allow doctors to strengthen the laser to shape structures in the eye, or nano-fabrication, for surgery.

Chen said the cost of making the prototype has been vastly lowered to HK$1.6 million from around HK$5 million for a traditional TPE microscope.

“However, after commercialization and further upgrade, the cost might rise,” he said.

The trial of the new 3D microscope has been handed over to Professor Christopher Leung Kai-shun from the Department of Ophthalmology and Visual Sciences, Faculty of Medicine.

“The most unique part of the new invention is the digital holography that creates a 3D image. After all, there is no 2D organ in our body,” Leung said.

The device has great potential for use in non-invasive medical procedures.

Leung said the DH-TPE microscope could be useful in tracking inter-cell metabolic activities by tracing the NADH, a product of respiration that can send out feeble but detectable fluorescence under the microscope.

If the intensity of the light drops, the cell is considered degenerating as in the case of the retinal cells of a glaucoma patient.

“Glaucoma is the leading cause of irreversible blindness worldwide,” Leung noted.

If the trials prove successful, the device will greatly help doctors to diagnose, monitor, and devise treatments to improve or even regenerate the patient’s eyesight.

Leung said the penetration power of the DH-TPE and TPE microscopes are not strong enough to probe other parts of the body except the eyes, but doctors hope the devices can also be used in examing the brain. 

It remains uncertain when human trials would commence. “The trial on live animals can take two to three years, so the application on humans will not be possible in at least two to three years,” Leung said.

A major challenge is turning the DH-TPE concept into a workable system. “It took us three to four years to create a system to control the microscope, but it is still very difficult to arrive at a user interface,” Chen said.

In particular, the team has to work on making the prototype user-friendly and build a suitable platform for the microscope.

The project, which started in 2013, received a couple of grants from the Innovation and Technology Commission, including HK$4 million for the DH-TPE microscope system and around HK$2 million for preliminary trial for medical uses in 2017.

Further trials will be conducted at the Hong Kong Eye Hospital.

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