Tactile graphics bring chemistry to low-vision students


11 January 2024

What’s the very first thing you do when faced with new graphical data or research imagery? The likely answer is that you look at it, scanning for overall trends and focusing on the details that will help you understand the implications of what you’re seeing. For the 253 million adults and children on the planet classed as blind or visually impaired, this sort of visual data is entirely inaccessible, excluding many from studying and working in science.

A new study, led by chemists and biochemists at Baylor University, aimed to change that. The stated goal was “to create a single universal (shareable) graphic that can be used by both sighted and blind persons presently in chemical research groups and classrooms, and those in high school or college wishing to matriculate to or join chemistry laboratories.”

Their solution was the lithophane; an artform first invented centuries ago. Its name comes from two Greek words: lithos (stone), and phainen, which means "to cause to appear", and it is a thin translucent plaque of material – often porcelain – that has been engraved or moulded to produce areas of varying thickness. In ambient light, the lithophane will look rough and opaque, but when backlit, it glows, with thinner regions appearing brighter than thicker ones, producing an image.

These days, high-resolution lithophanes can be 3D printed from any 2D image, and tools to convert images to topographs are often free to use. Members of the Baylor team first started experimenting with chemistry-themed lithophanes in 2022. Back then, they worked with a large cohort of undergrad and postgrad students to explore the lithograph’s potential as a data format that can be visualized by anyone regardless of eyesight. Incidentally, four authors of that initial study were PhD chemists that have been blind since birth or childhood, giving them a unique insight into the scale of the challenge. In 2022, they found that lithophanes depicting gel electropherograms, micrographs, mass spectra, and textbook illustrations could be interpreted by touch or eyesight at ≥79% accuracy.

Fig. 1. Three-dimensionally printed lithophanes of popular imagery. (A) Appearance of lithophane with front lighting (from overhead ceiling lights). (B) Same lithophane in (A) held up to the same ceiling light for back lighting. (C) Lithophane illuminated with natural outdoor lighting (front and back). Image credit: NASA. These images are in the public domain in the United States (i.e., published between 1926 and 1977 without a copyright notice).
Image credit: Baylor University and Science Advances (AAAS)

In this new paper, published today (11th January 2024) in the journal Science Advances, the Baylor team extended their work to highschoolers – specifically, a group of teenagers from the Texas School for the Blind and Visually Impaired (TSBVI). For this cohort, they developed a series of tactile, 3D-printed graphics that depicted chemical reactions and insect wings, and which could be interpreted solely by touch. These were used to run a series of outreach workshops, led by the same group of PhD chemists with blindness.

The chemical reactions were printed in the form of bond-line structures, and the team chose five esters which have pleasant natural aromas – isoamyl acetate (banana scent), ethyl decadienoate (pear scent), butyl butanoate (pineapple scent), ethyl propanoate (butterscotch scent), and methyl salicylate (wintergreen scent). The lithophanes were around 14 cm wide and 14 to 21 cm in length. The tactile protuberances were just under 5 mm high and 2 mm wide.

These graphics specifically did not incorporate braille in order to make them as accessible and shareable as possible. In the paper, the authors state that in the US, just 10 % of blind people can read (or are being taught to read) braille. While the validity of this statistic has been called into question elsewhere, it seems likely that braille literacy rates are low, and are even lower amongst sighted people. So, they designed each graphic to function without it.

Their results were impressive. They write, “High school students with blindness were able to accurately interpret lithophanes of esterification reactions despite little or no prior training in chemistry or experience with lithophanes …. The average accuracy for all students and all questions was 86%.”

Fig. 4. Lithophane graphics of five Fischer-Spier reactions between alcohol and carboxylic acid reagents and their ester products. (A) lithophane showing frontlit (left) and backlit (right) esterification of methanol and salicylic acid. (B) Frontlit lithophanes of reactions for ethyl propanoate (top-left), isoamyl acetate (top-right), butyl butanoate (bottom-left), and ethyl decadienoate (bottom-right). (C) tactile dimensions of lithophane graphics. (D) in contrast, swell form graphics of the same image present with shallow maximal protuberance (i.e., 0.6 to 0.7 mm off the surface of the paper).
Image credit: Image credit: Baylor University and Science Advances (AAAS)

The researchers then delivered a learning session which involved exploring lithophanes depicting the inner workings of different electron microscopes. Following that, students were given a ‘lithophane codex’; a series of different micrographs of butterfly wings, with each one showing progressively higher magnifications. They were asked how many layers of chitin scales they could visualize via tactile sensing, and again, results were positive, “Despite never visualizing any type of microscopic image before, seven of the eight students answered this question correctly.”

In my book Sticky, I featured Dr Sile O'Modhrain – a phenomenally talented researcher working to develop a refreshable braille display, which she described as “a tactile kindle”. Like members of the Baylor research team, O'Modhrain is blind. The time I got to spend with her made me realise just how critically important it is to involve people with lived experience at all stages of the research process – not just as ‘end users’. This paper further emphasises that message.


This is the first in a new series of short, news-y articles I’ll be publishing exclusively here on my website. The plan is that I’ll pick 1-2 interesting science papers every month and write a short piece like this on each. Eventually, I’d love to do an audio version too (similar to my segments with RNZ) but that will have to wait for now!