3D Printing

A hydrogel pen for Electrochemical Reaction & its Applications for 3D Printing

This is no ordinary pen.  This isn’t even an “ordinary” 3D printing pen. This is an incredible nanoscale hydrogel 3D printing pen. Created by Seongpil Hwang and staff of Korea University,  “amalgamates the precision of atomic force microscopy with a diffusion limited current from a microscopic electrode.”

korea university

There really isn’t any way for the process of how it works to be explained without getting technical.  Here we go:

At its tip the pen has a microscopic hydrogel pyramid.  The sharp apex of the pyramid of it is “soaked in an electrolyte to facilitate electrochemical reactions.” The hydrogel pen merges the fine control of atomic force microscopy with non-linear diffusion of an ultramicroelectrode, producing a faradaic current that depends on the small electroactive area. This hyper controlled contact between the tip and the ultramicroelectrode and manipulated faradaic reaction enables electroplating of precise nanostructures. 3D structures of platinum were deposited on a gold electrode – some with dimensions less than 100nm.

That’s not so bad.  As long as you know who Michael Faraday was and what ultramicroelectrodes and electroplating are, then you’re fine.

Platinum applied by the hydrogel 3D pen
Platinum applied by the hydrogel 3D pen

‘To the best of our knowledge, our hydrogel pen is the first example of a 3D printing pen,’ explains Hwang. ‘However, we were motivated by three techniques: dip-pen lithography developed by Chad Mirkin of Northwestern University, nanopipettes built by Patrick Unwin at the University of Warwick (UK) and micro-nozzles developed by Jennifer Lewis from Harvard University.’

According to materials scientist Harish Bhaskaran from the University of Oxford, “3D additive nanomanufacturing is the next frontier for rapid prototyping of nanoscale components.  There are many challenges at these scales and control of features, the reliability of these pens in the long-term, etc, will all play a role in their adoption in products in the future. However, this is an important first step and quite interesting because the technique is scalable.’

hydrogel 3D pen

What this pen “prints” is a hyper-localized electroactive area, for precise electrodeposition. In other words it prints the conditions and components necessary for a highly controlled electrochemical process.  The challenge and difference of this process compared with other more familiar 3D printing processes such as FDM and SLA is that they aren’t printing desired structures or STL files.

Basically, Hwang and company are using incredibly expensive highly conductive metals and materials to “write” tiny arbitrary structures.  Hopefully, they won’t be arbitrary for long.