Before we dive into the many uses of this exceptional substance, let’s start with the basics: “What is hydrogel?” Hydrogel is a 3D network of hydrophilic polymer material that quickly absorbs and retains a large amount of water (or other fluid). Incredibly versatile and environmentally sensitive, hydrogels are multi-functional across a variety of industries.
Hydrogels have become popular recently because of their unique properties:
• High water content
• Biocompatibility with most cells
• Chemical behavior
• Temperature sensitivity
• Relatively low cost
A hydrogel’s structure is the reason for its recent success and holds such promise for future use. With both viscous and elastic characteristics (viscoelastic) as well as being lubricious, hydrogels keep their structure by chemical or physical cross-linking individual hydrophilic polymer chains.
Hydrogels’ ability to contain/absorb water up to 99% of its volume makes them either soft and flexible (such as a contact lens) or highly absorbent (in a baby’s diaper). The porous nature of hydrogels allows for diffusion, or they can be dense. Characteristics depend on the hydrogel’s composition, which can be adapted depending on need. Hydrogels can be formulated to degrade/dissolve or be chemically stable.
What Is Hydrogel Used For?
The potential of hydrogels within so many various applications is incredible. So, naturally, scientists have been pushing the boundaries to uncover new uses. We’ve collected a few here, ending with hydrogel’s use in the converting world.
Hygiene ProductsHydrogels appear in various everyday products: hair gel, toothpaste, and cosmetics. Some superabsorbent hydrogels, the ones with acrylate-based materials, are used to absorb fluids in disposable diapers. Because hydrogels hold moisture away from skin, they prevent diaper rash, are comfortable, and promote skin health.
General Medical ApplicationsThe soft consistency, porosity, and high water content of hydrogels are very similar to natural living body tissue, making them good candidates for many medical applications. Common uses include contact lenses, nerve guidance conduits, tissue bulking agents, and in nucleus replacement technology.
When used as a wound dressing, hydrogels promote healing, provide moisture, and offer pain relief with their cool, high-water content. Hydrogel saturated onto a gauze pad can prevent the dressing from sticking to the wound surface.
“Smart” Wound DressingThese dressings have elements embedded within the hydrogel: microelectronic biosensors, microprocessors, wireless communication radios, etc. So, these wound dressings not only protect wounds, they can, for instance, respond to changes in skin temperature by releasing medication as needed (more on drug delivery below). They can even light up if a medication is running low.
“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 even when stretched.
Drug DeliveryWithin a stretchable hydrogel patch, inserted tubes or drilling holes create paths in the matrix. The high-porosity structure of hydrogels allows drugs to be loaded and then released, making long-term transdermal drug delivery easier and allowing for a controlled drug delivery system (DDS).
Other elements embedded in hydrogel — conductive titanium wires, semiconductor chips — allow drugs to be delivered on-demand from small drug reservoirs. Another advantage of using hydrogels for drug delivery is its sustained release abilities, resulting in a high drug concentration for a long time period.
Monitoring Drug DeliveryDelivering a drug using hydrogels is one thing. The real advantage comes with the ability to fully monitor that delivery using an electronics interface within hydrogel. There’s little concern when putting electronics in close contact with skin when soft, stretchable hydrogel conforms to the environment of the human body.
Suppose the drug amount is low in the reservoirs. In that case, an LED light embedded in the hydrogel alerts the patient and/or caregivers even if the hydrogel is stretched around flexible body parts.
Microfluidics and ConvertingIn order to use hydrogels to precisely deliver drugs or test liquid samples, intricate microchannels (ranging from submicron to a few millimeters) and circuits need to be built into the hydrogel. Top-end converters create microfluidic devices for organ-on-a-chip technology, test strips, or other tasks that require the movement or analysis of small molecules of liquid. Because hydrogels are non-toxic to most cells, feature designs and sizes can be molded onto them.
Experienced converters approach hydrogels’ low strength and reluctance to stick on contact with innovative adhesive solutions. Transport fluids. Protect samples. Allows for accurate detection. Precisely converted adhesive tape helps make it all happen.
Hydrogels already perform a wide range of functions. So, what’s next? Helping spinal cord regrowth? Organ generation? Tissue engineering scaffolds? And who knows what new microfluidic devices are in development?
What we do know is that the full potential of hydrogels has yet to be determined in everyday products and in specialized medicine. More progress is expected, and high-end converters like Strouse remain on the cutting edge. Wonder what other kinds of flexible material can be converted? Learn more by getting our Flexible Material Converting Q&A Guide.