It was August when thousands of bikers assembled in a city street, the dark evening ignited by streetlamps and wheels aglow with hues of red, green, blue and purple. A radiating energy pulsed through the crowd as gears shifted and feet were poised over pedals. The sound grew until a cheer of excitement rumbled, echoing between the buildings and towards the stars above. With a signal given, the bikers all took off at once and carried with them a hypnotic technicolor display of reflectors, string lights, and the ever-popular luminescence of glow sticks.
This is the Moonlight Ramble, a semi-annual bike ride through the roads of St. Louis, Mo. Participants cover their bikes in fluorescent rainbows, braiding them through the spokes and adorning their handlebars with vibrant color to match the city. The ghostly kaleidoscope sweeps through St. Louis like wil-o-wisps or clouds of fireflies; the effect is spellbinding and evokes the summer season.
One of the main attractions for events like the Moonlight Ramble is the display of city lights and decorative elements like glow sticks. Glow sticks are popularly used to brighten concert, party, and camping venues, always providing a fascinating source of light and color.
Glow sticks are one example of luminescence, the same principle which gives fireflies the power to light up and promotes the glow of some biochemical experiments. Such bioluminescent processes require luciferin or related bioluminescent substances; although glow sticks don’t contain luciferase reactions, they are no more complicated than the simplest radiant assay.
To honor luminescent sciences and end-of-summer festivities, we will illuminate the history behind these mesmerizing party favors, explain their mechanism, and suggest some experiments you can conduct with them.
From bike decorations to Halloween accessories, glow sticks have wide recreational use, but they were originally patented as a signaling device. This function is different from molecular chemical signaling – glow sticks were intended as emergency flares minus the open flame. Their reliable light source could be deployed in an emergency or by first responder services. Military personnel, divers, police and fire fighters were equipped with glow sticks to illuminate their fields of operation.
With this original purpose expanded, we now see the same devices being used at concerts and worn by costumed elementary schoolers. Even the inventor of the contemporary glow stick, Dr. Edwin Chandross, was surprised by their recreational popularity. When told about their use in music venues, his response was "Is that so? Maybe my granddaughter will think I'm cool now."
Dr. Chandross was inspired by witnessing luminol chemiluminescence at the Massachusetts Institute of Technology. He learned peroxalate esters are chemiluminescent when reacting with hydrogen peroxide; his discovery of the ideal proportion took one day, but he never patented it. Several years later, glow sticks using his formula were manufactured and sold to the public.
Mass-produced glow sticks were first applied in military activities then repurposed for concert apparel. Vice has published lore from the music community, citing the first instance of this practice at a 1971 Grateful Dead concert in New Haven, Conn. Here, the crowd began throwing activated glow sticks on stage for the performers to hold. This event became a trend that is now a tradition of widely distributing glow sticks at music performances worldwide.
Glow Stick Science
Glow sticks have a high value when it comes to low-cost entertainment: no batteries or electricity necessary, cheap to produce, portability and high functionality as well as resilience. They last for hours and cost dollars for dozens of tubes. They’re the perfect party favor or location marker just as bioluminescent indicators illuminate our experiments and track important molecules.
The shine of these tubes is engendered by chemiluminescence rather than bioluminescence. This reaction is not organic, yet when chemical substances are combined, they produce an equally vibrant glow without additional sources of energy. In chemiluminescence, electrons in chemical compounds are excited, and their return to a normal level releases energy as light.
It only takes the mixing of a few chemicals to produce the hypnotic glow. A base, often sodium salicylate, catalyzes this reaction with a dye to create an exothermic reaction. These chemicals, along with diphenyl oxalate, compose the outer solution within the glow stick tube. An inner glass vial holds hydrogen peroxide, and when this is mixed with the phenyl oxalate ester, phenol and peroxyacid ester are produced.
Peroxyacid spontaneously decomposes to activate the fluorescent glow stick dye with its energy. The dye is then responsible for releasing photons when its electrons are excited. The faster these chemicals mix, the faster and more luminescent the reaction. This is why breaking the glow stick in multiple places and shaking it results in a brighter output.
The concentrations of substances in this solution can be adjusted for a shorter, brighter glow or a lasting, dim light. Activation levels of light are the highest in energy and decay exponentially unless specific procedures are undertaken to revise this. By manipulating concentration, certain chemiluminescent recipes can engender brilliant light in a flash rather than glow. High quantities of sodium salicyate or other bases can have this effect.
How do glow sticks generate different colors, then? The incorporated dye determines photon wavelength, visible as the color of light emitted. Light is the most prevalent energy product of the reaction, because chemical transformations occurring within the tube can’t be sustained by a thermal reaction.
As such, glow sticks can be specifically designed to function in hot or cold climates. Heating a glow stick – like adding base substances – will encourage a faster, brighter, briefer light omission. Don’t microwave a glow stick or place it in/on any heating device to see it brighten; this is hazardous to you and your appliance because the tube can burst and spill fluid and glass everywhere. Alternatively, cooling extends the reaction with less extreme glow. An activated glow stick frozen or refrigerated will dim but resume glowing when the temperature rises again. The cold augments glow longevity. Glow stick dyes also retain their fluorescence under ultraviolet light – even a spent glow stick may brighten when exposed to black light.
For their economical cost and simplicity, these handheld science experiments are surprisingly versatile. Glow sticks can also be manufactured at home or in a laboratory. We’ll demonstrate some of their uses by outlining easy experiments anyone can conduct.
Home and Laboratory Experiments
Glow sticks can be manipulated with temperature, and the following experiment optimizes this property while maintaining the simplicity of glow sticks. The materials you need include a thermometer, two cups (preferably glass), water and ice, temperature-regulating gloves, tongs and three glow sticks of the same color.
Fill the cups, one with hot or near boiling water and the other with ice water. Snap and activate each glow stick, shaking them to start the reaction within. With the tongs, place one glow stick in each of the cups and leave the third out – this is the control, “room temperature” example. For the next several minutes, observe the varying reactions of each glow stick. You’ll notice the luminescence from the heated glow stick is brighter, but its light will be maintained for a shorter time; meanwhile, the near-frozen glow stick will have a dimmer glow but last longer.
An alternative method with this experiment would be to activate two glow sticks in the morning, storing one in the pantry and another in the freezer for the day. If they’re compared at night, the glow stick which was frozen should be more resilient.
For more involved fluorescent science, there are experiments for the laboratory environment. This involves more of a cautious approach, but it has a satisfying conclusion. The supplies include: six containers (again, glass), gloves and goggles, a tray or other platform, paper towels, a colander, an incising tool and three large, colored glow sticks: yellow, blue and pink. For a more robust sample, add extra glow sticks of the same colors.
Divide the containers into pairs. Put on the gloves and goggles before carefully cutting the top of each glow stick open and pouring the contents into individual glasses. All substances in the experiment are non-toxic, but the inner glass vial should be cautiously removed, rinsed (to prevent a precocious reaction), and broken open into the second set of containers. Avoid losing glass in the solution using the colander.
The pairs of containers should not be reacting, and turning off the lights in the room should demonstrate this – there is no glow. To initiate the reaction, add the activator (liquid from the glass vial) into the dye for each pairing. It should glow almost immediately!
To see an even more impressive reaction, the three reacting solutions can be poured together to produce a singular white glow. This result is accomplished through the combination of all light frequencies represented by the three glow stick colors. Dispose of the glass and liquid with the same protocol as other biochemical products.
Making Your Own Glow Sticks
We’ve covered the invention, science and applications of glow sticks, but what about their production? If you’re interested in creating your own fluorescent solution, we have a few recipes for you. There are potentially hazardous materials involved, so we recommend using gloves, a facemask and goggles in a well-ventilated setting. It is not recommended that children help with this experiment.
The chemical ingredients include hydrogen peroxide, sodium peroxide, potassium ferricyanide (the catalyst), luminol and water. Other supplies: a glass container and stirring instrument.
First, create the base inside the glass container. This solution consists of 1.5ml of hydrogen peroxide, .04g sodium hydroxide, .04g of luminol and 40ml of water. The solution should be thoroughly mixed with the stirring instrument to dissolving. To activate your base, slowly pour in potassium ferricyanide; higher quantities of this chemical will elongate the glow. It’s that simple!
This solution can be revised with a well-mixed base of 10ml diethyl phthalate, 100mg sodium acetate and 50mg TCPO. Add 3g of your choice of fluorescent dye for color. More TCPO and sodium acetate in the solution will increase light output. Combine the catalyst for this recipe, 3ml of 30% hydrogen peroxide. Now, you have an authentic chemiluminescent glow!
A long-lasting, solar-powered glow stick is also possible. Zinc sulfide – a glowing powder – can be combined with epoxy resin and hardened in a tube to produce a permanent glow stick, similar in operation to the glowing star stickers kids put on walls and ceilings. With sunlight exposure, the zinc sulfide absorbs and projects luminescence in the dark. This is a reusable option that provides endless light.
We hope you enjoy the simplicity of luminescence, whether you pick up a box of glow sticks from the store or craft your own in the laboratory!
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Glow Stick Science: Chemical Reaction Lab. Retrieved August 2, 2019, from https://www.adabofgluewilldo.com/glow-stick-science-chemical-reaction-lab/.
Harris, T. How Light Sticks Work (2001, November 1). Retrieved August 1, 2018, from https://science.howstuffworks.com/innovation/everyday-innovations/light-stick.html.
Heinecke, L. Glow Stick Science Experiment for Kids (2018, February 9). Retrieved August 2, 2019, from https://www.scholastic.com/parents/school-success/learning-toolkit-blog/glow-stick-science-experiment-kids.html.
Nichols, M. How to Make Glow Sticks Yourself — Backed by Science! (2017, January 3). Retrieved August 2, 2018 from https://schooledbyscience.com/make-glow-sticks-backed-science/.
Megan Hardie is an undergraduate student at The Ohio State
University’s Honors Arts and Sciences program. Her eclectic
interests have led to a rather unwieldly degree title: BS in
Anthropological Sciences and BA English Creative Writing,
Forensics Minor. She aspires to a PhD in Forensic Anthropology
and MA in English. In her career, she endeavors to apply the
qualities of literature to the scientific mode and vice versa,
integrating analysis with artistic expression.
GoldBio Staff Writer