What is Hydrogel, and How is it Used?

Would you ever put jelly on an open wound?

Hydrogel is a jelly-like material commonly used in clinical, electronic, agricultural, and other applications. It is a water-based substance with a soft consistency and moisturizing properties.

Over the past 40 years, Strouse has helped numerous customers build custom hydrogel products. Like the other materials we process, hydrogel is unique and can present its own set of manufacturing challenges.

By the end of this article, you’ll understand how hydrogel is used and be able to decide whether it suits your intended purpose.

What is Hydrogel?

Hydrogel is a 3D network of hydrophilic polymer material that quickly absorbs and retains water (or other fluid). As an incredibly versatile and environmentally sensitive material, hydrogel is multi-functional across various industries.

Hydrogel comes in solid or liquid form: its solid form is often rolled or sliced into sheets for wound dressings, while the liquid form can be sprayed onto or injected into tissues or other parts of the body. The structure is possible because it has viscoelastic properties resulting from the chemical or physical cross-linking of individual hydrophilic polymer chains (which readily attract or bond with water).

Hydrogels can swell when exposed to elevated temperatures, electric or magnetic fields, light, pressure, pH, ionic strength, solvent composition, or molecular species. There are many formulas, and the one you choose will depend on the available formats and how you expect it to behave in your application.

What is Hydrogel Used For?

Hydrogels are used in a wide range of biomedical, electronic, and other applications. These are a handful of its most common applications.

1. HYGIENE PRODUCTS

➡️Used in countless everyday products, such as hair gel, toothpaste, and cosmetics

Hydrogels’ ability to absorb up to 99% of their volume of water makes them soft, and flexible like a contact lens. Superabsorbent hydrogels (made from acrylate-based materials) absorb fluids in disposable diapers and sanitary pads. They help keep moisture away from the skin, making it more comfortable, helping prevent diaper rash, and promoting skin health.

The physical characteristics depend on its composition, which can be tailored to the intended use. It can be formulated to degrade, dissolve, or maintain chemical stability.

2. MEDICAL APPLICATIONS

➡️Used in electrodes, wound dressings, eye patches, burn bandages, nerve guidance conduits, tissue bulking agents, nucleus replacement technology, and more.

Hydrogels' soft consistency, porosity, and high water content are very similar to natural living body tissue, making them critical components in general medical applications.

Hydrogel wound dressings promote healing, provide moisture, and offer pain relief with their high water content. This cooling effect on the skin helps manage conditions such as chicken pox and shingles, and when saturated onto a gauze pad, the gel prevents dressings from sticking to the wound surface.

3. SMART WOUND DRESSINGS

➡️Used to protect wounds, respond to changes in skin temperature by releasing medication as needed, and even light up if a prescription is running low

Abilities such as monitoring and reacting to changes while remaining soft and flexible make smart hydrogel dressings highly applicable to chronic wound care. “Smart” wound dressings use electrical components embedded in the hydrogel, such as microelectronic biosensors, microprocessors, and wireless communication devices.

Motional wounds, i.e., injuries to stretchable body parts such as the neck or joints, are challenging to address. Smart wound dressings flex with the body, remaining in place as the patient bends a knee or elbow. Whatever elements or electronics are embedded remain functional in the dressing despite tension.

4. MICROFLUIDICS

➡️Used in organ-on-a-chip technology, test strips, and other applications that require the movement or analysis of small liquid molecules

You can easily use hydrogels to deliver drugs or test liquid samples because they already have intricate circuits and microchannels (ranging from submicron to a few millimeters) built into them. Since hydrogels are non-toxic to most cells, it is possible to mold features and sizes onto them.

5. HYDROGEL DRUG DELIVERY

➡️Used in long-term transdermal drug delivery and controlled drug delivery systems (DDS)

Inserted tubes or drilled holes create paths within the matrix of a stretchable hydrogel patch. Their high-porosity structure allows drugs to be loaded and released over lengthy periods.

Other elements embedded in hydrogel — conductive titanium wires and semiconductor chips — allow drugs to be delivered on demand from small drug reservoirs. Certain hydrogels can have sustained release abilities for drug delivery, allowing for high drug concentrations over a long period.

MONITORING DRUG DELIVERY

• Used in wearables such as continuous glucose monitors, as synthetic hydrogel electrodes

The advantage of delivering drugs using hydrogels is more than the delivery method—it allows healthcare providers to monitor the release using an electronic interface.

Hydrogel conforms to the human body's environment and maintains soft, stretchable mechanical properties while bringing electronics into close contact with the skin. Suppose the drug amount in the reservoirs was low. In that case, an LED light embedded in the gel would alert the patient or caregivers even while it’s stretched around flexible body parts.

6. AGRICULTURE

➡️Used in plant and soil water retention (allowing crops to grow in arid climates) and facilitating seed germination

Hydrogels are an effective tool for helping plants grow more efficiently by reducing water loss, thereby helping maintain crops. They can also be used to reduce waste and replace single-use plastics — holding hot water for hours without leakage and then dissolving in the ocean as intended.

The Benefits of Using Hydrogel

Depending on your needs, it can be an excellent choice for biomedical applications, smart sensors, and/or environmental science.

PROS:

• Creates a moist environment (conducive to wound healing)
• Mimics the composition and mechanical properties of natural tissues
• Soft and flexible
• Biocompatible with most cells
• Responds to chemicals
• Offers a soothing sensation for sensitive skin
• Temperature-sensitive

You may not realize it (unless you’ve touched it), but hydrogel’s unique structural properties can complicate precise, high-volume manufacturing — so it’s not the right choice for everyone.

CONS:

• Generally, it is a more expensive material
• Often requires a more complex machine setup to process
• Potentially challenging application
  

WHAT MAKES IT UNIQUE?

Hydrogels’ unique absorption capabilities can create moist environments catered to specific applications. Unlike hydrocolloids, which are often used on wounds with heavy exudation and drainage (such as pressure sores and ulcers), hydrogel dressings can provide relief for dry and surgical wounds. Plus, they are transparent, providing improved wound visibility.

Hydrogel’s flexible structure also makes it highly suitable for applications such as soft robotics, wearable electronics, and the miniaturization of modern electronics, which is why many researchers are studying hydrogel-based power sources and/or using multilayered hydrogel constructions to mimic the biological architecture of real organisms.

How Much Does it Cost, and Where Can I Find It?

The cost of hydrogel will vary depending on the type and quantity you intend to purchase. If you’re interested in purchasing hydrogel in bulk, here are some hydrogel manufacturers. Of course, if you want to cut hydrogel sheets into custom cut roll lengths or designs, you should likely reach out to a flexible material converter.

What to Consider Before You Order

Whether it’s helping with seed cultivation, spinal cord regrowth, organ generation, or even tissue engineering applications, you might be developing hydrogel projects of your own.

However, you’ll want to consider the following factors before finalizing any orders or designs.

MATERIAL PROCESSING CHALLENGES

It’s crucial to understand that, at a basic level, hydrogel is an extremely squishy, stretchy, and often sticky material, which can make it difficult to handle on a machine press. Cutting it into precise shapes at high volumes will require an expert (likely a flexible material converter), and that means being prepared to invest in die cut tooling, and possibly die cutting trials.

PACKAGING AND SHELF LIFE

If you leave an open jar of jelly in the sun all day, be prepared to find it shrunken and hardened when you return. Hydrogel is similarly sensitive to storage conditions, which is why it is imperative that you take precautions to ensure that your hydrogel products are properly insulated and maintained throughout shipping and handling.

Once the sheeted hydrogel is cut into shapes, those smaller parts will dry out faster. To prevent this, the most common way to protect sheeted hydrogel products is to heat-seal them into pouches. This will help ensure that your products remain in ideal condition (moist, not dried out) until it’s time to use them.

Now that you know the benefits and potential challenges, you’re ready to decide whether hydrogel is the right choice for your solution.