Research

Introduction

My major current research activities are related to nanotechnology; in particular, the development of novel nanomaterials for innovative systems and devices. I focus on magnetic nanomaterials, especially functionalized magnetic nanoparticles and magnetic nanoparticles based composites for sustainability, energy, bioX, Lab-on-a-chip and soft robotic applications. My work is targeted towards extreme service environments. The structure-processing-property-performance paradigm of materials science and engineering is fully exploited.

I have been elected as a Fellow of the American Society for Materials. My energy and bioengineering research (as well as teaching and education activities) have been recognized in the citation to my election as Fellow ASM.

I have achieved elected leadership positions in IEEE (USA), TMS (USA) and ASM (USA) and serve on the Functional Materials Division Council of TMS. I am the past Chair of the Magnetic Materials Committee of TMS (USA). I have served on the Editorial Board or as Editor of several prestigious international journals, including Nanomedicine and a Nature Publishing group journal.

I have organized symposia at international conferences in my field. I was the local chair of the prestigious IEEE INTERMAG conference held in Singapore. I have also delivered plenary, keynote and invited presentations at international conferences organized by leading professional societies, such as MRS, TMS, ASM and IUMRS. I have been invited to many prestigious universities in several countries (US, France, Israel, India, China..) to deliver seminars.

I have served as external PhD thesis examiner for a number of universities around the world and provided reference letters for faculty candidate selection and promotion in US, Australian and Indian universities.

I serve as an official nominator of the Japan Prize and reviewed major competitive grant proposals for several countries, including USA, Singapore, Saudi Arabia, U.K., France, Denmark and Czech. I have been selected as Adjunct/Visiting Faculty in USA, China and Indian universities.

My undergraduate mentees as well as graduate students have won a best paper award, global scholarships, design competition prizes, IEEE travel awards and poster prizes.

In terms of industry engagement, I have conducted consultancy projects with prestigious Fortune 500 multinational leading materials companies such as Applied Materials, Santa Clara, USA. My patent has also recently received recognition by a Rolls-Royce Inventors Award.

I have 313 publications, out of which 165 are in Tier 1 journals, including Progress in Materials Science, Materials Today, Advanced Materials etc.

I have received substantial external competitive funding, some of these grants relate to the Singapore Government’s new major initiatives in Sustainability and Advanced Manufacturing.

Accelerated Materials Development of Magnetic Materials

I have been pursuing the area of high throughput combinatorial synthesis, rapid property assessment and fast characterization for a number of years. Combining this with Artificial Intelligence and Machine Learning has led to my recent research project in accelerated materials development. The aim of this accelerated materials development project is to develop a machine learning guided materials development platform using high throughput computation and additive manufacturing based experiments to drastically reduce the magnetic materials development cycle. Currently, magnetically soft materials are mechanically weak. Hence, an outstanding challenge is to create a magnetically soft material capable of enduring the mechanical rigours of high-speed rotating electrical machines. Moving towards electrified transportation systems requires better electrical conversion systems, e.g., electrification equipment such as electric motors, generators, electric actuators, and magnetic bearings. Hence, there is a pressing need to develop better soft magnetic materials. Artificial Intelligence/Machine Learning tools will be used to focus efforts on the most promising regions of the multivariable parameter space.

The compositional space, consisting of tens of thousands of potential compositions, is being rapidly investigated (V. Chaudhary et al, Sci. Rep. (Nature Publishing Group), 8, 15578 (2018), Borkar et al, Acta Mater., 116, 63-76 (2016)). This parameter space is explored using a high-throughput experimental loop comprising rapid synthesis via a blown powder 3D printing tool with high compositional gradient capability. Other advantages include ease of exploring compositional space, better mechanical properties and higher build volume compared to a traditional selective laser melting tool.

Rapid characterization of magnetic properties is performed using a custom measurement setup. Machine-learning classification methods is used enabling a diagnostics-process optimization feedback loop, leading to the rapid identification and development of novel magnetic materials with higher performance metrics than current industry standard materials.

Magnetic materials for sustainable energy applications

i) Magnetocaloric materials: In the NRF funded project on magnetocaloric materials, novel low cost, magnetic cooling materials (V. Chaudhary et al, Magnetocaloric properties of Fe-Ni-Cr nanoparticles for active cooling, Scientific Reports (Nature Publishing Group), 6, 35156 (2016)) have been selected, processed, characterized and the magnetic properties evaluated in detail (V. Chaudhary et al, Prog. Mater. Sci., 100, 64-98 (2019) I.F. 23.75, 5 year I.F. 33.190]). Several PhD students and research staff have been trained under this program. A magnetic cooling device has been fabricated, patented and employed to evaluate these novel materials (V. Chaudhary et al, J. Phys. D: Appl. Phys., 50, 03LT03 (2017). Invited. R.V. Ramanujan et al US Patent No. WO2018026327 (2018)).

My deployment of phase transformations as an effective tool for structural and compositional control is particularly evident in the case of magnetic cooling materials, in which structural phase transitions are tailored to boost the magnetic cooling performance. There is considerable industry interest from several companies in Singapore, China, Japan, Israel, Macao etc. in the IP generated by this activity. This project was highlighted in a recent NTU’s Pushing Frontiers magazine article (issue 14, 2018).

Link to article: https://drive.google.com/file/d/1HjceW4nDOC3WKZB0X8vk05msMk0JoY0K/view

Sustainable green magnetic cooling to mitigate climate change poster:

https://drive.google.com/file/d/1W_F0zFTcXjBdiBw9ftd4XU_avSuR_Znk/view?usp=sharing

ii) Hard magnets: The funded project on rare earth free hard magnetic materials for use, e.g., in high performance motors and generators, has the potential to create a paradigm shift in the application space of hard magnets. A key performance metric of hard magnets is their energy product. We have developed ingenious bottom-up microwave (H. Parmar et al, Nanoscale 9 (37), 13956-13966 (2017)) and mechanochemical processes Y. Zhong et al, Nanoscale, 9, 18651-18660 (2017). Selected for back cover.) for the production of hard magnetic nanoparticles. A number of sophisticated characterization and property evaluation tools were utilized in these investigations. The new microwave based process for the synthesis of hard magnetic particles, has earned the Rolls Royce Inventors Award (R.V. Ramanujan et al, US Patent no. 20180130579 (2018)).

Magnetic materials for bio and bio inspired applications

In the area of magnetic nanomaterials for bioengineering applications, we undertake the highly interdisciplinary, innovative and potentially game-changing development of functionalized magnet-polymer composite nanosystems for

(a) targeted drug delivery and theranostics

(b) gene delivery

(c) artificial muscles, self healing and damage sensing systems

(d) Lab –on a chip

One of the key opportunities and challenges in biomedicine is the development of materials and devices to deliver drugs only to the disease site, followed by controlled delivery of these drugs (S. Kayal et al Mater. Sci. Engg. C, 30, 484-490 (2010)). With extremely fruitful interdisciplinary collaborations with doctors, radiologists and other medical specialists in SingHealth, we developed and tested magnet-polymer composite nanosystems. For example, doxorubicin loaded, thermoresponsive polymer shell-magnetic iron oxide core nanoparticles were developed for liver cancer treatment. We demonstrated, by in vitro and in vivo studies which utilized an ingenious combination of static and alternating magnetic fields, the feasibility of drug targeting, controlled drug release and multimodal cancer treatment (S. Purushotham et al Acta Biomater., 6, 502-510 (2010). Best Paper Award). We conducted modeling studies to provide predictive power to this largely empirical field. A great advantage of our materials and systems is their suitability as theranostic agents, i.e., therapy plus diagnostics. Functionalized magnet-polymer nanoparticles and magnet-polymer membranes with tailored surface properties are also being developed, in international collaboration through external funding, for leading-edge biosensing and water remediation applications.

In collaboration with the School of Biological Sciences, such magnet nanoparticle (core) polymer (shell) nanosystems were also employed for gene delivery. Such studies are of potentially high significance in developing non-viral methods of gene delivery.

Magnet-polymer composites were also developed for another interesting bioengineering application, i.e., artificial muscles for soft prosthetics (Nguyen et al, Adv. Mater., 24, 4041-4054 (2012). [# I.F. 21.950]) and in situ generated medical devices (D. Cohn et al, Invited Review, Adv. Healthcare Materials, in press (2019)).

These studies demonstrated excellent system level performance. The scope of development of IP and new products is high; hence, we are currently extending these studies by incorporating additional functionalities such as self-healing and self-sensing.

I also have 2 patents, one of which has won an inventor’s award.

1. R.V. Ramanujan and V. Chaudhary, US Patent No. WO2018026327 (2018).. An apparatus for transferring heat from a heat source to a heat sink. Invention showcased at several international innovation platforms, e.g.,Taipei International Invention Show, Technomart, Techinnovation (Singapore) etc.
2. R.V. Ramanujan, H. Parmar and X. Tan, Magnetic material and a method of synthesizing the same, US Patent no. 20180130579 (2018). Rolls Royce Inventors Award.

I am also the corresponding author of several book chapters, including:

1. S. Shukla*, P.K. Deheri* and R.V. Ramanujan, Invited Book Chapter on “Magnetic nanomaterials”. Book Title: Springer Handbook of Nanomaterials, Springer, New York (2013).
2. R.V. Ramanujan, Invited Book Chapter on “Magnetic particles for biomedical applications”. Textbook Title: Biomedical Materials, p. 477, R. Narayan (ed.), Springer, New York (2009).
3. A.K. Srivastava* and R.V. Ramanujan, Invited Encyclopedia Chapter on “Self assembly of magnetic nanomaterials”. Encyclopedia Title: Magnetic Nanostructures, H.S. Nalwa (ed.), p. 641, American Scientific Publishers, (2009).

Current funding

SERC AME Programmatic Funds (3 grants), NRF CREATE, DSO, MOE.

Key research awards I have received are:

Rolls Royce Inventors Award

Election as Fellow of the American Society of Materials

Acta best student paper award.

Best Oral Paper (Runner-up) Award, Gastroenterological Society Annual Meeting, Singapore

My research quality has been recognized:

i) International:

a) Editorial Board/Editor of several journals including Scientific Reports (Nature PG) and Nanomedicine

b) Visiting Faculty appointments including Univ. of N. Texas, South China University of Technology and Indian Institute of Technology.

c) External Thesis Examiner including Hebrew University of Jerusalem, Indian Institute of Technology, National University of Singapore.

d) Competitive Grant review solicitations from premier scientific organizations in the US (NSF), France, Czech, Denmark, U.K. etc.

ii) National:

a) PSF Grant review subcommittee chair (A*STAR)

b) RISE committee (NTU)

c) MOE Grant review committee (NTU)

My student mentees have also achieved national and international recognition in the form of best poster awards, best paper awards, Global scholarship and young inventor’s award.

I have performed industry related consultancy projects related to magnetic materials including for the Fortune 500 Company, Applied Materials, Santa Clara, USA.

In summary, my research activities focus on magnetic nanomaterials, especially related to sustainability, energy and bioX applications. I also have current research interest in high temperature structural materials for energy efficient engines.