Skip to Content

How Cocoons Are Turned Into Optical Devices

A simple process turns cocoons into optical devices with biological applications.
December 22, 2008
Preda stirs cut-up cocoons in a salt solution. The cocoons are boiled in a beaker over a hot plate to dissolve the protein that holds them together, sericin. The silk fibers, now pure fibroin protein, will be dissolved in another salt solution.
Using a syringe, Preda loads the syrupy silk solution into a dialysis cartridge. The cartridge will be placed in a beaker of water, which will draw the salt out through the cartridge’s clear window. Finally, Preda will use a syringe to suck out the pure water-fibroin solution left behind, which she’ll store in the fridge.
To make a hologram, a researcher deposits the water-based solution of pure silk fibroin onto a mold with a pipette. Fibroin makes a good optical material because it’s translucent when it dries, and it conforms well to both the nanoscale and macro­scale details of molds like this one.
After drying for several hours, silk optical devices like the hemoglobin-containing card in the researcher’s left hand can be peeled off their molds. Each iridescent square has been molded into a different device. One is a diffraction grating that can act as an oxygen sensor.

Keep Reading

Most Popular

This nanoparticle could be the key to a universal covid vaccine

Ending the covid pandemic might well require a vaccine that protects against any new strains. Researchers may have found a strategy that will work.

How do strong muscles keep your brain healthy?

There’s a robust molecular language being spoken between your muscles and your brain.

The 1,000 Chinese SpaceX engineers who never existed

LinkedIn users are being scammed of millions of dollars by fake connections posing as graduates of prestigious universities and employees at top tech companies.

Stay connected

Illustration by Rose Wong

Get the latest updates from
MIT Technology Review

Discover special offers, top stories, upcoming events, and more.

Thank you for submitting your email!

Explore more newsletters

It looks like something went wrong.

We’re having trouble saving your preferences. Try refreshing this page and updating them one more time. If you continue to get this message, reach out to us at customer-service@technologyreview.com with a list of newsletters you’d like to receive.