(7fk) Electrodeposition-Based Additive Manufacturing: Combining Bipolar Electrochemistry with Scanning Probe Methodology for Freeform Fabrication | AIChE

(7fk) Electrodeposition-Based Additive Manufacturing: Combining Bipolar Electrochemistry with Scanning Probe Methodology for Freeform Fabrication

Authors 

Braun, T. M. - Presenter, National Institute of Standards and Technology
Recent advances in additive manufacturing technologies (such as fused deposition modeling or selective laser sintering) have been primarily driven by straightforward integration of computer software with hardware components, enabling simple 3D fabrication from computer aided design files. Despite these recent advances, a similar transition has yet to emerge for fully software-reconfigurable, electrodeposition-based prototyping. Typical industrial electrodeposition patterning techniques require a series of mask, deposition, etch, and planarization steps to develop fully formed 3D objects, limiting their customization. Localized direct-write electrodeposition techniques can bridge the advantages of electrodeposition-based micro/nanofabrication with user-friendly software intrinsic to present commercially successful additive manufacturing methods. Dimensions of the pipettes or electrodes used in localized electrodeposition dictate the spatial resolution of the material deposited (existing pipette/electrode fabrication techniques achieve sub 100nm resolution) while vertical resolution is controlled by the applied current and/or electrochemical waveform, providing methods for monolayer thickness control. Additionally, implementing bipolar electrochemistry in localized electrodeposition removes the need to electrically connect to the substrate during electrodeposition, providing improved automation and easier integration of software with hardware components.

Research Interests:

My research background is centered around electrochemical engineering; specifically in electrodeposition and electroanalytical characterization. My broader interests align in electrochemical design and integration of fundamental transport, kinetics, and thermodynamics for innovative solutions to industrially relevant problems. Research in the area of bipolar electrochemistry during my PhD provides me with a unique and comprehensive skillset, as bipolar electrochemistry involves intricate coupling of the following:

  1. Thermodynamic principles similar to those seen in electroless deposition or nanoparticle syntheses.
  2. Spatially segregated heterogeneous reduction and oxidation kinetics on a single substrate analogous to corrosion phenomenon.
  3. Specifically designed ohmic distribution in an electrochemical cell to minimize shunt current losses akin to design of flow batteries.

During my postdoctoral studies at NIST, I have continued research in metal electrodeposition while adding expertise in various electroanalytical measurement techniques. The topics being probed include:

  1. Effect of chemical adsorption on metal surfaces during electrodeposition for morphological control, directed growth, and negative differential resistance (S-NDR) generated spatial patterning.
  2. Implementing localized electrodeposition with scanning probe technology for 3D freeform fabrication and combinatorial characterization of thin film materials.
  3. Electrocatalysis of thin film metal alloys and metal oxides/hydroxides for energy applications.

A variety of electroanalytical measurement techniques are being utilized to characterize the above systems including: rotating disk electrochemistry, electrochemical quartz crystal microbalance, microelectrodes, scanning droplet cell electrochemistry, and scanning electrochemical microscopy.

Future Directions: I plan to combine aspects of my PhD and postdoctoral studies to create a research environment grounded in electrochemical fundamentals while engineering materials and processing challenges for electronics and energy applications. The rising need for more efficient energy technologies and the imminent transition to next generation computer processor manufacturing for quantum computing applications will require continued development, processing, and fabrication of thin film and 3D-structured materials. Integrating bipolar electrochemistry with scanning ion conductance microscopy and electrochemical impedance spectroscopy will create a new technique for in-situ measurement of film growth during 3D freeform fabrication, furthering customization capabilities for electrodeposition based additive manufacturing at the nanoscale. This technology can also be used for combinatorial characterization of materials for their electrocatalytic and corrosion resistant properties.

Teaching Interests:

My academic teaching interests align with my research background in studying the coupling between fundamental mass transport, thermodynamics, and kinetics for engineering electrochemical systems. Education in each of these core chemical engineering concepts individually is vital to the development of chemical engineering students with the requisite skill-set to succeed in industry. However, students commonly only put these fundamentals together during their capstone senior design project exploring design and optimization of a single chemical process at factory production scale. With the types of jobs that chemical engineering students are entering after graduation spanning a greater range of industries than traditionally, I plan to focus on incorporating core chemical engineering concepts across a broader range of commercial applications in class to better prepare students for their careers. Courses I have interest in teaching are a reflection of my past research and teaching experiences. These include core chemical engineering courses such as momentum/mass transport, reactor design, senior design, graduate level surface kinetics/catalysis, and an interdisciplinary elective course on electrochemical fundamentals. Within the classroom I aim to build an environment that fosters creativity, critical problem solving, and independent thinking while promoting group discussion and collaboration. This will be achieved with group exercises, example problems, and open-ended questions/discussions mixed into lecture periods and recitations. In my prior experiences as a teaching assistant, guest lecturer, and mentor I found that willingness and availability of the educator for individual or small group exchanges provides the students with a low-stress opportunity to ask questions, stimulate comprehensive discussion, and provide immediate feedback on lectures. Thus, office hours and group mentorship circles will be utilized by myself and teaching assistants to promote these activities.