Harry Potter diary inspires self-writing paper

Tom Riddle’s diary in the Chamber of Secrets movie prompted Professor Wei Shen to create paper that displays blood types as letters


In a case of life deliberately imitating art, the film Harry Potter and the Chamber of Secrets has inspired a scientist to design his own self-writing paper.


Professor Wei Shen of Monash University in Melbourne was watching a scene from the movie in which the boy wizard writes a questions in Tom Riddle’s diary – “Do you know anything about the Chamber of Secrets?” – only for the answer – “Yes” – to magically appear on the page.

The scene, dreamed up by author JK Rowling, led Professor Shen to develop his own magic paper that classifies blood types and displays them in the form of letters.

“The movie shows that you can have a text result, and that’s where the idea comes from,” he said.

The sensor paper is coated with a layer of water-repellent material, with four “windows” left clear so they can absorb liquid. When a drop of blood comes into contact with the paper, antigens related to blood types determine which window will absorb the liquid and therefore which combinations of letters in the ABO blood type system will appear.

Professor Shen hopes the invention will help eliminate errors in blood type identification, which can prove fatal. 

“We found that more than 80 per cent of the population… could not interpret results even if the result from a perfectly functioned blood typing assay was presented to them,” he said.

“But with a device that can spell out the patient’s blood type in written text, people will know their blood type easily.”

Comparisons with existing blood typing technologies used in hospitals and laboratories show the paper to be just as accurate but faster, cheaper and simpler to use.

Dr John Brennan, who holds the Canada Research Chair in Bioanalytical Chemistry, said of the development, “the major novelty is in the ease of reading the strip by spelling out the letters for specific blood types… I think that there are places where such strips might be used, such as rapid response scenarios – battlefield casualties, automobile accidents, etc – where rapid blood transfusion is required.”

“In such cases an unambiguous readout such as that provided by these strips would be important.”