Research

The primary focus of Panat Lab is to invent new manufacturing methods in the area of additive manufacturing that lead to novel 2D or 3D structures (see CMU article). The methods are inspired by nature. The resulting structures are then used either to study fundamental science problems or to realize new device classes with novel functionalities. The scientific problems are in the areas of structure-property relations (e.g. properties of microscale 3D cellular/lightweight materials, effect of porosity, etc), while the devices include fast-charge/discharge and high capacity batteries, thermoelectric generators, advanced wireless sensors, stretchable metal films, and biomedical instruments. These devices are used in the areas such as IoT, soft robotics, smart contact lens, wearable electronic clothing, robotic skins, and bio-patches etc.

Dr. Panat did his graduate research in the area of Theoretical and Applied Mechanics (diffusion and fracture), and then worked on manufacturing R&D at Intel Corporation for 10 years. As a result of this background, the group emphasizes on interdisciplinary research and works on fundamental problems that have strong industry applications.

News about the lab: Business Wire, TCT Magazine, India Today

1. New Additive Manufacturing Methods

We have been investigating new manufacturing methods for metallic parts that lead to new geometries and structures. Using Aerosol Jet 3-D printing, we were able to arrange nanoparticles in 3D space for the first time at length scale of tens of micrometers. This patent pending process can make highly complex structures as shown in the pictures below. We have also developed printing of polymers in 3D (also patent pending). The nanoparticles can then be sintered by thermal, laser, or pulse photonic energy. Part of this research is sponsored by NSF. Video link

 Fig. 1. Printed Microscale 3D Structures

Publications: 

• M. Sadeq Saleh, C. Hu, and R. Panat, “Three Dimensional Micro-architected Materials and Devices using Nanoparticle Assembly by Pointwise Spatial Printing”, Science Advances, 3, e1601986, 2017. PDF   http://dx.doi.org/10.1126/sciadv.1601986
• J. Geng, M. T. Rahman, R. Panat, and L. Li, “Self-assembled Axisymmetric Microscale Periodic Wrinkles on Elastomer Fibers”, ASME Journal of Micro and Nano-manufacturing, Vol. 5, Issue 2, pp. 021006, 2017. PDF  http://dx.doi.org/10.1115/1.4036112
• M. T. Rahman, L. Renaud, M. Renn, D. Heo, R. Panat, “Aerosol Based Direct-Write Micro-Additive Fabrication Method for Sub-mm 3-D Metal-Dielectric Structures” Journal of Micromechanics and Microengineering, Vol. 25 (10), 107002 (2015). PDF

2. Three Dimensional Li-ion Batteries

The hypothesis of this research is that if we control the porosity of a structure from nano to microscales, we can increase the capacity of the batteries and the charge-discharge rates. The microscale additive manufacturing method we developed is highly useful for this application. We have also worked on developing models for the stresses in Li-ion batteries to find thermodynamic conditions under which the battery will show a crack growth. This research has been on phenomenal success and a paper will exciting results is underway. This research is sponsored by NSF (link).

Publications: 

• R. Panat, J.Park, M. S. Saleh, and J. Li, “3D-Printed Lattice Batteries”, Homeland Defense Information Analysis Center (HDIAC) Journal, 5 (4), pp. 11 (2018). PDF
• M. Sadeq Saleh, Jie Li, Jonghyun Park, and Rahul Panat, “3D Printed Hierarchically-Porous Microlattice Electrode Materials for Exceptionally High Specific Capacity and Areal Capacity Lithium Ion Batteries”, Additive Manufacturing, Vol.23, pp 70-78 (2018). PDF
• J. Li, X. Liang, R. Panat, and J. Park, “Enhanced Battery Performance through Three-Dimensional Structured Electrodes: Experimental and Modeling Study” Journal of the Electrochemical Society, 165 (14), A3566-A3573 (2018). PDF
• J. Li, M. Leu, R. Panat and J. Park, “A Hybrid Three-Dimensionally Structured Electrode for Lithium-ion Batteries via 3D Printing”, Materials and Design, Vol. 119, pp. 417-424, 2017. PDF
• R. Panat, “A Model for Crack Initiation in the Li-ion Battery Electrodes”, Thin Solid Films, Vol. 596, pp. 174 178 (2015). PDF
• Z. Song, T. Ma, R Tang, Q. Cheng, X. Wang, D. Krishnaraju, R. Panat, C. K. Chan, H. Yu, and H. Jiang, “Origami Lithium Ion Batteries”, Nature Communications, 5:3140, 10.1038/ncomms4140, (2014). PDF

3. Advanced Brain Machine Interfaces/Biomedical Neural Devices

Our group has developed the most advanced brain-machine interfaces using through work carried out over a year. This work is in collaboration with the Yttri group from the Biological Science department at CMU. Two provisional patent applications have been filed. We  recently received exploratory R21 grant funding from the National Institutes of Health (news) to explore this area. Please contact Dr. Panat for further information. We have also worked on 3D printed biosensors (publication below).

Publications: 

• H. Yang, M. T. Rahman, D. Du, R. Panat, and Y. Lin, “3-D Printed Adjustable Microelectrode Arrays for Electrochemical Sensing and Biosensing”, Sensors and Actuators B: Chemical, Vol. 230, 600-606, 2016. PDF

4. Lightweight Strong Structural Materials

Our group is working on using additive manufacturing to create strong lightweight structures. These materials intend to overcome the trade-off between strength and ductility – a problem that has dogged scientists for a long time (unexplored space in the graph above). A scaffold with near fully dense truss elements is shown above. The research also aims to use some nanoscale material manipulation methods to increase strength. Lastly, we also study the combined effect of porosity and grain size on the elastic and plastic regime of the materials at 1 um to 100 um length scales. This research will lead to new paradigms in designing materials with suitable properties. Part of this research is sponsored by the National Science Foundation (link).

• M. Sadeq Saleh, Mehdi HamidVishkasougheh, H. Zbib, and R. Panat, “Polycrystalline Micropillars by a Novel 3-D Printing Method and Their Behavior under Compressive Loads”, Scripta Materialia,  Volume 149, 144–149, 2018. PDF

5. Advanced Wireless Sensors

The aim of this research is to create and evaluate very high surface to area to volume ratio films to create highly sensitive sensors. We also aim to make metamaterial-like structures that can have unusual response to a given stimulus. We also evaluate electrical properties of the sensors and demonstrate device performance. High performance strain sensors, touch sensors, biochemical sensors have been demonstrated. We are also working on printed antennas that can be coupled with these sensors for in-situ monitoring in harsh environments such as high temperature and irradiation. This research is sponsored by the US Department of Energy (DOE).

Publications: 

• M. T. Rahman, R. Moser, H. Zbib, C. V. Ramana, and R. Panat, “3D Printed High Performance High Temperature Sensors”, Journal of Applied Physics, 123, 024501, 2018. PDF
• M. T. Rahman, J. McCloy, C. V. Ramana, and R. Panat, “Structure, Electrical Characteristics and High-Temperature Stability of Aerosol Jet Printed Silver Nanoparticle Films”, Journal of Applied Physics, Vol. 120, Issue 7, pp. 075305-1 to 11, 2016. PDF
• M. T. Rahman, A. Rahimi, S. Gupta, and R. Panat, “Microscale Additive Manufacturing and Modeling of Interdigitated Capacitive Touch Sensors”, Sensors and Actuators A: Physical, Vol. 248, 94-103, 2016. PDF
• H. Yang, M. T. Rahman, D. Du, R. Panat, and Y. Lin, “3-D Printed Adjustable Microelectrode Arrays for Electrochemical Sensing and Biosensing”, Sensors and Actuators B: Chemical, Vol. 230, 600-606, 2016. PDF
• M. T. Rahman, J. Gomez, K. Mireles, P. Wo, J. Marcial, M. Kessler, J. McCloy, C. Ramana, and R. Panat, “High temperature physical and chemical stability and oxidation reaction kinetics of Ni-Cr nanoparticles”, Journal of Physical Chemistry – C, Vol.121 (7), pp. 4018–4028, 2017. PDF 

6. Flexible/Stretchable Electronics

Stretchable interconnects are needed in several applications such as flexible and wearable devices. Our research is based on the hypothesis that length scale controls the plastic instability in a film and this parameter can be used to create films with very high stretchability. The research is very fundamental and involves finding the mechanisms that result in strain hardening of the film if the sample length is continuously reduced. This principle was used to make a patented process that involves periodic bonding of a metal film to a soft substrate and then stretching the film to >100% strain without breakage! We have also created films that do not show an increase in resistivity when repeatedly stretched to about 25% strain! 

Our success in recent results has been picked up by different media all around the world. Here are some of the links-

News: Researchers create stretchable metal conductors for electronics
YouTube Video on Stretching the system– https://www.youtube.com/watch?v=CgbG8OHgHuU

Publications:

• Y. Arafat, I. Dutta, R. Panat, “Super-stretchable Metallic Interconnects on Polymer with a Linear Strain of up to 100%” Applied Physics Letters, 107, 081906, 2015 PDF 
• Y. Arafat, I. Dutta, R. Panat, “On the Deformation Mechanisms and Electrical Behavior of Highly Stretchable Metallic Interconnects on Elastomer Substrates”, Journal of Applied Physics, Vol. 120, Issue 11, pp. 115103-1 to 11, 2016. PDF  DOI: http://dx.doi.org/10.1063/1.4962453