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Sweet diagnostics and smartphone spiders

by Sam Lemonick
October 23, 2021 | A version of this story appeared in Volume 99, Issue 39


Photograph showing a person's left hand with black sleeve on a wood table in the background. In the foreground they hold a phone in their right hand. On the screen of the phone is an image of their hand on the table, with a digital model of a spider superimposed on the hand.
Credit: University of Basel, MCN
Itsy-bitsy spidAR: A new augmented reality app helps people with a spider phobia by exposing them to a digital model of one.

Conductive candy

Some people don’t like Tootsie Roll candy, Newscripts has learned. Regardless of the validity of that opinion, researchers have come up with an alternate use for the little chocolate logs: shaping them into electrodes that diagnose kidney disease or track ovulation (ACS Appl. Mater. Interfaces 2021, DOI: 10.1021/acsami.1c11306).

Beelee Chua of Korea University has worked for years developing medical diagnostic devices. He says he noticed that single-use tests—which help ensure equipment remains sterile between uses—are both expensive and generate a lot of waste. So Chua and his former student Donghyun Lee, now of Pusan National University, have looked for ways to repurpose other materials to potentially reduce the cost and waste of diagnostics.

They previously described using gummy bears to measure bite force (Sens. Actuators, A 2019, DOI: 10.1016/j.sna.2019.03.013). Now they’ve shown that Tootsie Roll candies molded with a grid pattern can trap saliva and, when connected to some simple electronics, help measure changes in electrical conductivity that can be used to diagnose chronic kidney disease or track ovulation for family planning.

Chua says Tootsie Roll candy works for three main reasons. First, they (and many other foods) conduct electricity. Second, soft candies are malleable enough to form the patterned electrodes. And third, they are made in large, consistent batches that ensure any individual piece of the candy will produce similar conductivity measurements. Soft candies are also inexpensive and available around the world, and Chua thinks this approach could help make medical testing more accessible in developing nations.

He and Lee have also brainstormed what they call a “baby pop,” a version of the device in lollipop form for easy ovulation testing. That project is on hold while Lee is training to be a dentist. (Newscripts acknowledges the irony.)

And Chua thinks these ideas can be taken even further. “The next big leap we’re going to look at is: is it possible to create an electrochemical electrode using different candies?” he says. He envisions a whole circuit made from candy, including candy batteries, which could lead to edible diagnostics. Can’t be worse than wax lips, right?


Spidey desensitizing

Photograph of fingers in blue lab gloves holding a Tootsie Roll molded into a square shape with a grid pattern pressed into its surface, and two metal rods extending from one side.
Credit: Beelee Chua
Trick or treatment: Tootsie Roll candy can be repurposed as electrodes to help detect kidney disease or track ovulation.

If a friend were scared of spiders, you probably wouldn’t drop a spider on the table in front of them. But that’s the exact idea behind exposure therapy, which deliberately confronts a person with the source of their phobia. The theory, backed up by studies, is that acclimation will lessen someone’s fear and help them learn new responses to that trigger.

Anja Zimmer of the University of Basel and colleagues are updating that therapeutic approach for the smartphone era (J. Anxiety Disord. 2021, DOI: 10.1016/j.janxdis.2021.102442). Their app, called Phobys, superimposes a realistic digital model of a spider onto whatever surface the phone’s camera is pointing at. So, for instance, the spider might walk on your kitchen table or wall, or even across your hand.

Phobys currently has 10 levels of increasingly intense encounters, lasting 2 min each, including tasks like moving closer to the spider. After each level, the user rates how they felt, and the app doesn’t let them proceed to the next level until their feeling of fear starts to diminish.

Zimmer says that in-person exposure therapy can be costly and time consuming, both for patients and therapists. Virtual reality (VR) approaches have been tried as well, but these require expensive headsets. The group thinks its app can make exposure therapy more accessible.

A randomized controlled trial of the app showed that users felt less fear of spiders after six sessions. Zimmer herself had a spider phobia (which she previously treated with VR exposure therapy), and she says she thinks her experience helped the team create an effective tool.

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