Hybrid additive-subtractive laser fabrication platform for shaping hydrogels

Patent metadata

Field	Value
Publication number	US-2021237354-A1
Application number	US-201916973235-A
Country	US
Kind code	A1
Filing date	Jul 11, 2019
Priority date	Jul 11, 2018
Publication date	Aug 5, 2021
Grant date	—

Abstract

A hybrid laser printing (HLP) technology that utilizes ultrafast laser in sequential additive-subtractive modes to create 3D hydrogel constructs. The approach involves the synergistic use of additive crosslinking and subtractive ablation processes that are conventionally mutually exclusive. HLP can be operated at virtually any penetration depth and allow fabrication of multi-layer hydrogel constructs at micrometer resolution. HLP was used to print ready-to-use functional chips using commonly used hydrogels for potential cellular communication and migration applications. HLP was also found to be compatible with in situ printing of cell-laden hydrogel constructs. HLP makes shaping of soft hydrogels into 3D multi scale functional devices possible.

First claim

What is claimed is:

1 . A system for forming a structure from a hydrogel, comprising:
a stage having a sample holder for holding a hydrogel prepolymer solution and a window formed through the sample holder; a femtosecond laser source capable of emitting a plurality of laser pulses having a first predetermined wavelength; a second harmonic generator aligned with the laser source to generate a second predetermined wavelength for a first portion of the plurality of the laser pulses; a digital micro-mirror device aligned with the second harmonic generator and the window of the stage to spatially modulate the ultraviolet wavelength pulses according to a first predetermined pattern so that the hydrogel prepolymer solution is cross-linked into a layer of a hydrogel polymer according to the first predetermined pattern; and an objective lens aligned with the laser source and the window of the stage to allow a second portion of the laser pulses having the first predetermined wavelength to ablate a plurality of voids in the layer of the hydrogel polymer.

2 . The system of claim 1 , wherein the stage is configured to translate away from the window after the layer of the hydrogel polymer after the plurality of voids are ablated.

3 . The system of claim 2 , wherein the first predetermined wavelength is 800 nm.

4 . The system of claim 3 , wherein the second predetermined wavelength is 400 nm.

5 . The system of claim 4 , wherein the layer of the hydrogel polymer is spaced apart from the window by a zone having a predetermined thickness and including the hydrogel prepolymer solution.

6 . The system of claim 5 , wherein the plurality of voids are formed in an ablation range adjacent to the zone.

7 . The system of claim 6 , wherein the hydrogel prepolymer solution comprises polyethylene glycol diacrylate.

8 . The system of claim 7 , wherein each of the plurality of laser pulses are 150 femtoseconds wide.

9 . The system of claim 7 , wherein the plurality of laser pulses have a repetition rate of 80 MHz.

10 . A method of forming a three dimensional structure from a hydrogel prepolymer, comprising the steps of:
(a) positioning a hydrogel prepolymer in a sample holder of stage, wherein the sample holder has a window formed through a bottom of the sample holder; (b) using a micro-mirror device to selectively direct a first plurality of laser pulses having a first predetermined wavelength from a femtosecond laser source according to a predetermined pattern through the window to cross-link a portion of the hydrogel prepolymer and form a layer of hydrogel; (c) directing a second plurality of laser pulses having a second predetermined wavelength through the window to ablate a plurality of voids in selected portions of the layer of the hydrogel; and (d) moving the stage so that the layer of hydrogel is moved away from the window of the sample holder; and (e) repeating steps (a) through (d) until a predetermined three dimensional structure is completed.

11 . The method of claim 10 , wherein the first predetermined wavelength is 800 nm.

12 . The method of claim 11 , wherein the second predetermined wavelength is 400 nm.

13 . The method of claim 12 , wherein the layer of the hydrogel polymer is spaced apart from the window by a zone having a predetermined thickness and including the hydrogel prepolymer solution.

14 . The method of claim 13 , wherein the plurality of voids are formed in an ablation range adjacent to the zone.

15 . The method of claim 14 , wherein the hydrogel prepolymer solution comprises polyethylene glycol diacrylate.

Assignees

• Soman Pranav
• Kunwar Puskal
• Xiong Zheng
• Univ Syracuse

Inventors

• Soman Pranav
• Kunwar Puskal
• Xiong Zheng

Classifications

• G02F1/37 Primary

  for second-harmonic generation {(G02F1/3532 takes precedence)} · CPC title

• B29C64/277 Primary

  using multiple radiation means, e.g. micromirrors or multiple light-emitting diodes [LED] · CPC title

• G02F1/372

  Means for homogenizing the output beam · CPC title

• B33Y10/00

  Processes of additive manufacturing · CPC title

• B33Y70/00

  Materials specially adapted for additive manufacturing · CPC title