ICE | The Israel Chemist and Chemical Engineer | Issue 8

6 Scientific Article The Israel Chemist and Chemical Engineer Issue 8 · November 2021 · Kislev 5782 Upper left, clockwise: Ehud Greenberg, Dr. Nina Armon, Dr. Eitan Edri and Ornit Nagler-Avramovitz are PhD students (Nina and Eitan have graduated) in the lab of Prof. Shpaisman. Dr. Yuval Elias is the scientific editor of the Chemistry Department at Bar-Ilan University. Hagay Shpaisman is an associate professor at Bar-Ilan University and leads the laboratory of directed material assembly, devising and developing new methods for bottom-up assembly. Abstract: Laser-guided assembly of microstructures where materials are patterned into 2D/3D structures with (sub) micron resolution and less waste than standard top-downmethods has many applications includingmicroelectronics, sensors, andmedical devices. Liquids allow a simple setup andmay be easily handled and recycled. However, this simplicity conceals various underlyingmechanisms that cannot be identified by simply observing the initial or final materials. Furthermore, this field is of interest to chemists, physicists, and chemical/material engineers where each group is focused on different aspects of the deposition process, sometimes leading to confusion regarding the overall mechanism. Here we offer a methodical short overview where mechanisms are divided according to the material source – preformed or locally synthesized, and then by the driving force. Various methods are compared, and advantages and limitations are discussed. Finally, we illuminate various future directions for advancing this exciting field. Laser-guided printing Ehud Greenberg,a,b Nina Armon,a,b Eitan Edri,a,b Ornit Nagler-Avramovitz,a,b Yuval Eliasa and Hagay Shpaismana,b* aDepartment of Chemistry and bInstitute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel *Email: [email protected] 1. Introduction Formation of patterns is important for many applications including medicine, robot ics, electronics, and food production. Structures produced by bottom-up approaches, in two dimensions as well as in three-dimensional additive manufacturing (AM), may be more complex and incur less waste than traditional methods. The microscale is particularly important for electronic, optoelectronic, photonic, electromechanical and medical devices, as well as for various sensors. Moreover, personalized macro-scaled products such as implants and drugs often have micro-sized features, which play an important role. Highly precise optical manipulation of light offers outstanding resolution, while printing at high speeds is achieved by rapid steering of the laser. A large variety of materials including metals, oxides, alloys, polymers, and biological cells have been assembled by laser-based methods. Techniques based on liquids are desirable as they allow simple setups, easy handling, excellent resolution, and recycling with minimum waste. Focusing on assembly based on lasers in liquid environments, the common setup (Figure 1) encompasses severa l mechanisms. Variants combine different principles of operation. Different mechanisms, operation modes and material characteristics are therefore easy to miss. Whereas reviews on printing with lasers deal primarily with preformed materials, local synthesis is mentioned mainly in reviews that survey a wide range of methods, such as those composed by Elder [1] and Ngo [2] and coworkers. Specific material families have also been reviewed, e.g. metal microstructures by Hirt and coworkers [3]. Here, we offer a short overview that presents both preformed material deposition and in situ synthesis. We refer the interested readers to our recent indepth progress report [4]. Methods are divided by the driving