Have you ever wondered what that clear goo is that you put in your hair to style it? Or what gives moisturizers that smooth, hydrated feel on your skin? There’s a good chance it contains something called hydrogel.
Hydrogels are everywhere these days – in your bathroom, medicine cabinet, local hospital, and even in advanced research labs. But what exactly are they and why are they used in so many products we interact with every day?
In this guide, I’ll walk you through everything you need to know about this fascinating material – from what hydrogels are made of to their many current and future applications. Get ready to become a hydrogel expert!
What Are Hydrogels?
Let’s start with the basics – what are hydrogels?
Hydrogels are networks of crosslinked, hydrophilic polymer chains that can absorb and retain large amounts of water. Just like a sponge soaking up water, hydrogels are able to swell and hold high water content – up to thousands of times their dry weight!
The polymers that make up hydrogels are hydrophilic, meaning they attract and are soluble in water. Some common ingredients used to create hydrogels include polyvinyl alcohol (PVA), polyethylene glycol (PEG), and polyacrylamide (PAM).
When these polymers are crosslinked together into a network, it creates a flexible, jelly-like structure capable of absorbing and retaining moisture. The crosslinks act like little anchors, holding the hydrogel together even as it absorbs water.
The end result is a soft, squishy, biocompatible material with very unique properties:
- High water content – up to 99% water!
- Softness and flexibility
- Porous structure allows diffusion of molecules
- Biocompatible and non-toxic
- Can be engineered to be biodegradable
Thanks to these special characteristics, hydrogels have become incredibly versatile materials with applications across many different industries.
Now let’s look at some of the main uses and applications of hydrogels today.
Medical and Healthcare Uses
One of the most common uses of hydrogels is in medicine and healthcare. Their soft tissue-like properties make hydrogels perfectly suited for interacting with the human body.
Some medical uses of hydrogels include:
Due to their moisture retention abilities, hydrogel wound dressings are often applied to injuries like burns, ulcers, and cuts. The hydrogel helps hydrate the wound area while also preventing bacterial infection.
Hydrogel dressings create a cooling sensation on the skin for comfort and pain relief. They also reduce the risk of adhesion to the wound compared to gauze dressings.
Recent innovations have led to “smart” hydrogel wound dressings embedded with medication reservoirs and biosensors to actively promote healing.
Transdermal Drug Delivery
Hydrogels can be used to provide controlled and sustained release of drugs through the skin. Transdermal patches made of hydrogel can delivery pain medication, hormones, and other therapeutic agents over an extended time with a single application.
The release rate can be tailored by engineering the porosity and composition of the hydrogel. This allows medication to be delivered in a more convenient, non-invasive way compared to injections.
Tissue Engineering Scaffolds
Due to their biocompatibility, researchers have explored using hydrogels as scaffolds to repair damaged tissues in the body like cartilage, bone, nerves, and skin.
The hydrogel scaffolds provide a template for cells to attach and multiply. They can also be loaded with cells, growth factors, or medication to aid in regeneration.
Soft hydrogel contact lenses allow oxygen to pass through to the cornea. This makes them a safer long-term option compared to non-breathable lenses.
Fun fact – around 70 million people in the United States alone wear contact lenses!
Hydrogels are used in toothpaste and mouthwash to keep the mouth and gums hydrated and healthy. Their antiseptic properties also help prevent cavities and gingivitis.
They are sometimes used to temporarily fill holes in teeth and can also help dentures stick firmly in place.
Diapers contain superabsorbent hydrogels (SAPs) that can soak up urine rapidly. This keeps moisture away from the skin to prevent discomfort and rashes.
The hydrogels used in diapers can absorb over 300x their weight in fluid! SAPs are also used in feminine hygiene products for the same purpose.
Conductive hydrogels are being developed into skin-mounted biosensors that can track vital signs like heart rate, glucose levels, etc. This could allow constant, real-time monitoring of health.
Pretty amazing medical applications, right? And there are many more possibilities as the technology continues to advance.
Now let’s look at some everyday uses of hydrogels.
Cosmetic and Personal Care Uses
Hydrogels are widely used in cosmetics and hygiene products thanks to their soft, tissue-like consistency and moisturizing properties.
Some cosmetic applications include:
Skin Care Products
The humectant properties of hydrogels allow them to hold moisture against your skin, keeping it hydrated and reducing wrinkles. You can find them in moisturizers, anti-aging creams, and masks.
Hair Gels and Sprays
Hair gels use hydrogels to provide flexible hold and shine to hairstyles. The moisture retention also prevents hair drying out and splitting.
Hydrogels in toothpaste help freshen breath, protect teeth, and hydrate the gums to prevent sensitivity.
Contact Lens Solution
Hydrogel contacts need to be stored in solution that keeps them hydrated and sterile between uses.
As mentioned before, superabsorbent hydrogels in diapers lock away moisture to keep baby comfortable and prevent diaper rash.
Feminine Hygiene Products
Similar to diapers, hydrogels are used in pads and tampons to quickly absorb fluid. This keeps you feeling dry and clean.
Now that you know about the medical and personal uses, let’s move on to some industrial and technological applications.
Industrial and Technological Applications
With their tunable properties and ability to respond to environmental stimuli, hydrogels are highly useful materials for engineers and scientists across many fields.
Some of their industrial applications include:
Adhesives and Sealants
Hydrogels can act as effective adhesives thanks to their tackiness and moisture retention. They can stick strongly to surfaces while still being removable and flexible over time.
Hydrocolloids are added to foods like ice cream and salad dressings to improve texture, viscosity, and moisture retention.
Hydrogel crystals can absorb hundreds of times their weight in water. They are mixed into soil to help plants better retain moisture and nutrients.
As absorbent gels, hydrogels can remove contaminants and solid waste from water during purification processes.
Microfluidic hydrogel circuits allow precise manipulation of tiny liquid samples and reactions, revolutionizing medical testing.
Conductive hydrogels are being used to develop flexible biosensors, electronic skin, and implantable neural interfaces.
3D Cell Culture
The porous structure and excellent biocompatibility of hydrogels make them useful as synthetic extracellular matrices for growing cells in the lab.
Hydrogels are being engineered to mimic natural tissues like cartilage, skin, and blood vessels for research and therapeutic use.
Controlled Drug Delivery
As mentioned earlier, hydrogels can provide sustained, localized release of therapeutic agents within the body.
And believe it or not, we’ve still only just scratched the surface of what hydrogels may be capable of in the future, from environmental remediation to futuristic cybernetic bio-interfaces. The possibilities are endless!
But for now, let’s round up with a quick look at some current environmental applications.
In addition to human uses, hydrogels can be quite helpful for environmental conservation efforts:
- Oil spill clean up – Hydrogels can absorb oil and congeal it into a solid, making it easier to remove from water.
- Water purification – Absorptive hydrogels can extract pollutants, toxins, and microplastics from drinking water sources.
- Heavy metal removal – Hydrogels can help remove hazardous heavy metals like lead and mercury from contaminated soil or industrial wastewater.
Researchers continue looking for new ways to utilize hydrogels to help solve pressing environmental problems. For example, hydrogels are being studied as water retention aids for crops in drought-prone regions.
The versatility of this futuristic material seems endless!
Hydrogels are incredibly versatile materials finding use in everything from diapers and hair gel to state-of-the-art medicine.
Their unique properties allow hydrogels to be customized for many different applications across diverse fields. Scientists have only begun tapping into their potential through advanced research.
Hydrogels will likely continue improving our lives in unexpected ways in the coming decades. I don’t know about you, but that makes me excited to see what innovative uses people will discover next!
So next time you use some hand sanitizer, spread cream on your face, or put in contact lenses, you can marvel at the futuristic hydrogel material that makes them work. What an amazing substance!