Nature designs materials with exquisite 3D micro-architecture. For instance, the tissues in our bodies are composed of cells, proteins, carbohydrates, and other components that intimately and wisely share space. The spatial disposition of each component and its vicinity or interface to others have crucial roles in the functionality of a given tissue or material. This means, for example, that a tissue needs all the components together and interacting if it is to work properly as a beautifully designed functional structure, rather than as a homogeneous mass (i.e., together, not scrambled).
Our lab uses and develops novel microfabrication technologies to produce biological microsystems with high control on their 3D micro-architecture. A signature technology of our lab is Chaotic Printing.1,2 This is a simple, effective, and novel printing technique that is rooted in chaos theory or, more precisely, in the physics of chaotic mixing in a laminar regime. The main strength of this novel microfabrication strategy lies in its ability to create densely packed microstructure at high resolution and speed, but in a predictable manner. The creation of a large amount of interface between materials is a desired attribute in many applications.
The basic idea behind chaotic printing is different and very simple: Chaotic flows are used to create complex structures. When we pour milk into coffee, the turbulent flow caused by agitation rapidly develops a structure. However, we do not use turbulent flow, as this is difficult to model, predict, and reproduce; instead, we use chaotic flows in printing. A drop of “ink” (i.e., a drop of fluorescent beads, nanoparticles, or cells) is injected into a viscous, Newtonian, cross-linkable liquid. Chaotic flow is then applied to draw very complex structures in just a few flow applications. We can achieve nano-resolution structures in the matter of minutes.
We envision the use of this technology for the fabrication of complex biological tissues. For instance, we can print tumor-like tissues, where healthy and cancerous cells coexist and then use these tissues as biological models to test anti-cancer drugs. We can also produce by use sacrificial inks to create thick hydrogel constructs containing convoluted channels within them to mimic microvascularized tissues. Communities of bacteria (like those found in the human gut or skin) can also be printed with a controlled degree of intimacy to study bacterial interactions and their effects in disease and health. We also envision the use of this technology in a wider spectrum of applications, like biocatalytic surfaces, reinforced materials, and supercapacitors, among others.