micro 3d printing of a temperature-responsive hydrogel using projection micro-stereolithography

Stimuli-
Over the past few decades, responsive gels that have shown physical or chemical changes in response to environmental conditions have attracted increasing attention. Poly(N-
Acrylic acid)(PNIPAAm)
As a temperature-responsive gel, there is extensive research in various fields of science and engineering.
However, the manufacture of PNIPAAm has been heavily dependent on traditional methods such as molding and exposure techniques, which are essentially limited to twodimensional (2D)space.
Here, we report three. dimensional (3D)
Use high-print PNIPAAm
Manufacturing technology of projection micro-resolution digital additive
Stereo printing (PμSL).
By controlling the manufacturing process parameters and polymer resin composition, the temperature-dependent deformation of 3D printing PNIPAAm can be controlled.
It is also proved that the continuous deformation of the 3D printed PNIPAAm structure changes the expansion transition temperature of PNIPAAm by selectively incorporating ion monomer.
This fast, high resolution and scalable 3D printing method for stimulation
Responsive gel can achieve many new applications in different fields, including flexible sensors and actuators, bio-
Medical devices and tissue engineering. Stimuli-
Responsive gels are polymer networks that perform physical or chemical changes to environmental stimuli such as temperature, pH, and electric fields.
Various stimuli
People have been exploring responsive gels and their applications for the past few decades. Poly(N-
Acrylic acid)(PNIPAAm)
The most widely used temperature-
Responsive gels are widely studied and used in many applications such as microfluid devices, drug delivery carriers, cell culture substrates, and soft actuators.
PNIPAAm exhibits a large and reversible volume change in water at a lower critical solution temperature (
LCST, usually 32-35 °c)due to a coil-
Spherical transformation of polymer network chains.
At temperatures below LCST, the NIPAAm molecules in the water environment exhibit a hydrophilic behavior with an extended coil structure, which results in water absorption and expansion.
However, when the temperature is higher than LCST, the sparse water base becomes more active, resulting in the transformation of molecules into shapes similar to tight balls.
This drastic change causes the trapped water molecules to escape from the gel network, resulting in a significant reduction in volume.
Although there is a growing focus on PNIPAAm and its wide range of applications, the manufacturing technology of PNIPAAm is limited to two simpledimensional (2D)
Manufacturing methods such as molding and printing hinder the full use of their unique material properties.
Recently, efforts have been made to create 3D shapes from 2D PNIPAAm paper using origami methods.
However, PNIPAAm geometry with high resolution and high aspect ratio is still challenging.
Recently, it is reported that the use of commercial extrusion-
But it is still limited to simple 2D extrusion geometry and low resolution.
Other high resolution 3D Micro
Including three manufacturing technologies.
Three dimensional laser chemical vapor deposition (3D-LCVD)
Electrolytic manufacturing (EFAB), and micro-
Stereo printing (μSL)
Disadvantages such as Long manufacturing time, high cost and limited available materials also exist.
In this study, we propose the use of projection micro-
Stereo printing (PμSL).
P μ sl is a flat print
Fast, cheap and flexible additive-based manufacturing technology for material selection.
Generate 3D models using a computer-aided-design (CAD)
Software and digital slicing into a series of crossover
Segmented images of 3D models.
Each digital image is transmitted to a digital maskviolet (UV)
The light is then projected and focused on the surface of the photo by narrowing the lenscurable resin.
The UV of the pattern converts the liquid resin into a solid layer by photopolymerization.
Once a layer is formed, the linear phase drops the sample holder of the constructed object in order to introduce fresh liquid resin for the next layer.
The subsequent layers aggregate in the same way at the top of the previous layer.
Repeat this process until all layers of the build 3D object are completed (Fig.
And supplementary map).
Since p μ sl uses projection exposure technology, the entire layer is aggregated by a single UV irradiation for a few seconds.
Therefore, the manufacturing speed is much faster than the serial processing technology of the nozzle or laser beam must be the grating
Scan each layer.
In addition, the use of refactored digital photo masks eliminates the need for multiple physical photo masks, otherwise the production process will be very expensive and time consumingconsuming.
Pμsl is also compatible with various photos
Including gathering (Ethylene glycol)(PEG)
PLA (PLA), poly(caprolactone)(PCL)
And their polymers.
In this work, we show the reversible deformation of PNIPAAm 3D printing using p μ sl and various 3D printing PNIPAAm micro-structures.
We also studied the effects of p μ sl process parameters and polymer resin composition on temperature-dependent expansion behavior of 3D printed PNIPAAm gel.
The sequential deformation of the structure of 3D printing PNIPAAm is also shown by selectively incorporating ion monomer, thus changing the expansion transition temperature of PNIPAAm.