International researchers came together recently to study more about complex 3D printing materials, releasing their findings in ‘Tough and conductive polymer hydrogel based on double network for photo-curing 3D printing.’
Both conductive properties and hydrogels are popular for use in 3D printing today, and in this study, they are combined for greater innovation in flexible sensors. Made of polymerics, hydrogels—as their name would suggest—are able to hold water and are often used in research projects centered around bioprinting, cross-linking, soft tissue engineering, and more. While deemed suitable for a range of applications, up until recently their uses have often been limited due to inferior mechanical properties.
Conductive hydrogels, however, are attractive for use in research and development due to the following:
- Strong adhesion
- High porosity
- Good swelling
All of the above-mentioned features make CHs excellent choices for use in human motion sensors, and even wound dressings, bolstering infected skin for regeneration.
“Currently, printable CHs are mostly ionic conductive with a free-moving ion,” stated the researchers. “Due to the simple preparation process and large deformation, it is very suitable for 3D printing.”
Challenges arise in using conductive hydrogels, however, as flexible chains deform but a single network structure is easily broken down, causing low mechanical strength; however, combinations such as conductive polymer (polypyrrole (PPy), polythiophene (PTh), polyaniline (PANI), and hydrogel may come together to create interpenetrating polymer network (IPN) or double network (DN) structures.
Serving as a chain to manage stress within the structure, conductive polymer hydrogels (CPHs) are polymerized, immersed, and then integrated into the network, forming the IPN. The authors report, however, that molding time is too long, at one to two days, and thus ‘far from meeting the requirements of 3D printing…”
In this study, hydrogel synthesis was performed via DLP 3D printing.
Electrical conductivity of sample hydrogels was evaluated under EDOT content of 12 wt%.
“The electrical conductivity of dry gel was ascribed to π-electron conjugated polymer of PEDOT. For ruling out the influence of ions, the evaluation of PEDOT was based on the conductivity of the dry sample,” stated the authors.
“Compared to only one oxidizer APS, Fe3+ as electron acceptor took electrons from π-electron conjugated polymer of PEDOT to form carrier in the chains . When the FeCl3 content was low, few carriers led to a poor electrical conductivity. When FeCl3 was excessive, too much oxidizing points led to a decrease in the molecular weight of PEDOT, which weakened the contact of electrically conductive phases. At the same time, peroxidation also destroyed the conjugated structure of PEDOT , which caused the electrical conductivity decline. When the ratio of EDOT, APS and FeCl3 was 1:1:1, the electrical conductivity of dry gel is the largest (0.5 S cm−1).”
The hydrogel exhibited swelling as EDOT was increased; however, a constant state was attained as it decreased. In testing the sensor application, the researchers created a sample ‘finger,’ attaching the hydrogels and noting that as the finger bent, the hydrogels were able to transform fast mechanical signals into electrical signals. Varying pressures were noted, and the fingers were able to deform and stay without breaking.
“It was demonstrated that hydrogels could be used as pressure sensors to monitor human activity,” concluded the researchers. “This study provided a new idea for 3D printing conductive hydrogel, which could be used in stretchable electrical devices and soft robotics applications.”
What do you think of this news? Let us know your thoughts! Join the discussion of this and other 3D printing topics at 3DPrintBoard.com.[Source / Images: ‘Tough and conductive polymer hydrogel based on double network for photo-curing 3D printing’]
You May Also Like
3D Printing News Briefs, September 9, 2021: Events, Materials, & More
In today’s 3D Printing News Briefs, the first Formnext + PM South China finally opens this week. In materials news, a biomedical company introduced what it calls the first purified...
US Navy Issues $20M to Stratasys to Purchase Large-Format 3D Printers
The U.S. Navy has been steadily increasing its investment into practical 3D printer usage, as opposed to research. The latest comes in the form of a whopping $20 million contract...
3D Printing Webinar and Event Roundup: August 22, 2021
From food 3D printing and GE Additive’s Arcam EBM Spectra L 3D printer to 3D printing and CAD in a post-pandemic world and topology optimization, we’ve got a busy week...
The Largest 3D Printed Structure in North America: a Military Barracks in Texas
ICON’s latest 3D printed training barracks structure in Texas signals another positive step for the additive construction industry. Described by the company as the largest 3D printed structure in North...
View our broad assortment of in house and third party products.