In a bid to combat deforestation, researchers from theMassachusetts Institute of Technology(MIT) and theCharles Stark Draper Laboratoryhave developed a new method of 3D bioprinting wood-like materials.
The technique leverages lab-grown living cells from the Zinnia elegans plant, and could one day be used to print all manner of custom shapes like chairs, tables, and other wood products without the need to chop down any trees.
The team has also been able to fine-tune the physical and mechanical properties of the printed structures by adjusting the chemicals used in the cell growth process. This includes characteristics such as density and stiffness.
Ashley Beckwith, lead author of the study, said, “The idea is that you can grow these plant materials in exactly the shape that you need, so you don’t need to do any subtractive manufacturing after the fact, which reduces the amount of energy and waste. There is a lot of potential to expand this and grow three-dimensional structures.”
The problem of deforestation
Trees are a crucial natural resource heralded for their life-sustaining decarbonization effects, and we use wood for everything from buildings and furniture to paper and tools.
然而，尽管成本相对较低和可用性相对较低，但木材并不是无限的，人类却在缓慢，但肯定会通过森林砍伐减少其供应。为了将其置于背景下，据估计，世界每年损失约1000万公顷的森林。以目前的速度，世界上许多森林可能会在接下来的几个世纪中消失。
Beckwith adds, “Trees and forests are an amazing tool for helping us manage climate change, so being as strategic as we can with these resources will be a societal necessity going forward.”
A more sustainable alternative
为了减少我们对大自然母亲的依赖，研究人员现在正在寻找培养皿的替代品。麻省理工学院小组首先将活细胞从仙网星植物的叶子中隔离，对它们进行两天的培养，然后将其转移到凝胶培养基中，在那里它们被重要的营养素和两种不同的激素滋养。
通过在此初始生长阶段调整激素水平，研究人员发现他们可以随着植物细胞的生长而改变植物细胞的物理和机械性能。然后，使用3D打印机将载有细胞的凝胶材料挤压成复杂的结构，例如小型常绿树的轮廓。在黑暗中孵育三个月并脱水后，印刷结构表现出最终的物理特性。
It was determined that the lower the hormone exposure, the lower the density of the plant cells. With higher hormone levels, the plant cells grew with smaller and denser cell structures, as well as more stiffness. The team even managed to achieve a stiffness comparable to that of some natural woods. As a bonus, the MIT team was able to show that the printed cell structures could survive and even continue to grow for several months after being extruded.
Luis F. Velásquez-García, co-author of the paper, said, “I think the real opportunity here is to be optimal with what you use and how you use it. If you want to create an object that is going to serve some purpose, there are mechanical expectations to consider. This process is really amenable to customization.”
For future work, Beckwith’s team intends to investigate how genetic and other chemical factors influence cell growth. They also hope to apply the bioprinting method to other plant species, including trees such as pine. Ultimately, they envision a future where we could one day lab-grow wood products with properties based on their intended applications, like high strength and insulative structures for the walls of buildings.
Further details of the study can be found in the paper titled‘Physical, mechanical, and microstructural characterization of novel, 3D-printed, tunable, lab-grown plant materials generated from Zinnia elegans cell cultures’.
3D打印木材的追求
The 3D printing of wood and wood-like materials is no new venture. Last year, 3D printer OEMDesktop Metal在推出其子公司Forust时成为头条新闻，该品牌的重点是3D printing functional end-use wood partsvia binder jetting. The Forust process works by upscaling waste byproducts from the wood manufacturing and paper industries (sawdust and lignin) and mixing them with a special bio-epoxy resin composite that can be printed.
在其他地方，另一种选择wood substitute made from kombucha tea wastewas awarded last year’s national詹姆斯·戴森奖. Pyrus, a 3D printable wood-mimicking material made from bacteria cellulose grown on the top of kombucha tea as it brews, was developed byUniversity of Illinois学生Gabe Tavas。此后，他一直在试图扩展其材料的生产。
Subscribe to the3D Printing Industry newsletterfor the latest news in additive manufacturing. You can also stay connected by following us onTwitter, liking us onFacebook, and tuning into the3D Printing Industry YouTube Channel.
Looking for a career in additive manufacturing? Visit3D Printing Jobsfor a selection of roles in the industry.
Featured image shows microscopic images of the Zinnia plant cells being grown prior to 3D printing. Image via MIT.
