How do you see the almost-invisible? First, you build a better flashlight.

Professor Dayong Jin has built some of the best – and smallest – flashlights in the world, and is using them to watch bacteria and viruses in action, and pick out single cancer cells among millions of healthy ones, potentially paving the way for a range of new, molecular-level therapies.

For his flashlights and 14 years of other interdisciplinary work, Professor Jin has won the $50,000 Malcolm McIntosh Prize for Physical Scientist of the Year.

The award – one of the Prime Minister's Prizes for Science  – was presented at a ceremony in Canberra on Wednesday. 

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Cells, the basic building blocks of all life, are almost transparent, making individual features very hard to pick out, even with today's high-powered microscopes.

Our current techniques to see inside them are akin to blundering through a dark house with a candle – everything is murky and out of focus.

Or we use a huge laser, which allows us to see clearly but incinerates the whole house in the process.

So Professor Jin, working in his lab at the University of Technology Sydney, designed the world's tiniest flashlights.

Each is only 13 nanometres across, thousands of times smaller than a red blood cell. 

They have illuminated an extraordinary minutiae of biological processes, such as thin strands of RNA floating ethereally through 50-nanometres "pores" in a cell's nucleus.

"The old microscope techniques were like using a candle," he says.

"We use an electric light."

Professor Jin, 38, is extremely prolific. He has had a hand in at least 30 published papers in the past two years.

The award recognises his most significant breakthrough, published in the journal Nature in March: using lanthanide-doped nanocrystals to illuminate the insides of cells.

The nanocrystals, christened "Super Dots", can be attached to certain molecules within a cell.

When Professor Jin shines a low-powered laser on them they light up like tiny fairy-lights. 

They give biologists a low-cost tool to follow the processes of life in real-time, something which they had struggled to do until now. 

Before his work, scientists would often use a large laser to illuminate cells, which worked well enough but had the side effect of literally frying the cell to death.

The lower-powered laser used to activate the flashlights does not harm cells, allowing scientists to watch them go about their busy lives.

His work has led to the creation of a device for diagnosing prostate cancer.

It can spot a single cancerous cell in a patients' urine, and is the first of several low-cost devices Professor Jin hopes to commercialise.

Professor Ann Roberts, an expert in microscopy with the University of Melbourne, said observing a living cell's processes in real-time at the molecular level was important in developing new medicines and therapies.

"Jin's work is outstanding, and it's going to be a very valuable contribution to the field," she said.