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Interview With Amay Bandodkar 2016 Metrohm Young Chemist Award Winner


Mr. Amay Bandodkar, a Ph.D. candidate in the laboratory of Professor Joseph Wang at the University of California in San Diego, is the recipient of the 2016 Metrohm Young Chemist Award. His work on wearable electronics was selected from a field of 70 submissions. Robert Stevenson had an op- portunity to interview Amay at Pittcon.


RLS: Thank you for meeting me. I want to congratulate you on winning the award. Please tell me about yourself.


AB: I was born and raised in Mumbai, India. In college, I started to focus on chemistry since I was fascinated by the fact that chemistry dictates the properties of everything in the universe. I was especially enticed by the field of nanotechnology and the impact it has on modulating the properties of materials. During my undergraduate work, I found the field of biosensors of particular interest since these devices have immense applications in healthcare, environmental protection and even defense. So I worked as an undergraduate researcher in my department, and also had the opportunity to work at national labs in India and Germany. Professor Wang’s work in electrochemical sensors is unparalleled, and I knew it would be the best place to pursue my Ph.D. I asked if he would be interested in taking me as his graduate student, and he agreed.


RLS: How did you get started on your research?


AB: Wearable devices have become a hot topic; knowing the impact they would have, Professor Wang entrusted me with developing these devices. I worked with my team toward this goal under Professor Wang’s valuable guidance. We started with simple, flexible, paper-based wearable chemi- cal sensors that could detect important metabolites—such as glucose and lactate—and electrolytes—such as sodium and ammonium—directly on the human body. Thereafter, we focused on giving the sensors more “skin- like” properties such as stretchability and the ability to self-heal. We spent a considerable amount of time identifying the best ratio of elastomeric binder, conductive filler and solvent to obtain printed devices that could stretch up to 500% without having much of an effect on their electro- chemical properties (see Figure 1).


We worked on developing self-healing printed devices since mechanical damage-induced device failure is the Achilles’ heel of printed electronics (see Figure 2). First, micro-capsules loaded with the healing agent (an organ- ic solvent) were synthesized. These capsules were then dispersed within an acrylic-based carbon ink. The prepared inks were used to print self-healing devices. When the printed trace is damaged, the capsules along the crack also rupture, leading to the release of encapsulated organic solvent, which dissolves the binder. This results in rearrangement of the conductive par- ticles, which restores the mechanical and electrical contact across the crack. Our experiments showed that this restoration takes places within 3–5 sec.


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Wearable sensors need to be in contact with the skin. The devices must be soft and stretchable like human skin, and also robust and nontoxic. I started working with several materials and eventually selected a silicone- based elastomer that is widely used for prosthetics, masks and toys as the stretchable binder. I found that by carefully manipulating the ink com- position and device design, I could stretch the printed device as much as 500% without breaking it. Our research is still in the initial phase; we are actively looking for better ink components that will allow us to fabricate inexpensive devices that possess even more striking properties.


RLS: Can circuits be created on the membrane? AB: Yes, we can use conductive inks to print circuits.


RLS: What kinds of sensors have you developed and how do they work?


AB: I worked with my team to develop wearable electrochemical sensors for noninvasive detection of glucose (for diabetes), lactate, sodium, ammonium and pH (for fitness monitoring). These devices leverage electroanalytical techniques such as amperometry and potentiometry. We functionalize the printed sensors with specific enzymes and chemical reagents to detect the desired chemical species with high selectivity. These sensors thus gener- ate signal (current or potential) proportional to the concentration of the chemical species.


RLS: What about cost? I can see that these could be expensive, at least at first.


AB: Not really—the flexible/stretchable substrate and conductive ink are not expensive. If this technology is expensive, no one will use it. My goal is for the cost to be less than $1, which would make the devices disposable. We rely heavily on screen-printing technology, since it allows large-scale, low-cost fabrication of high-fidelity sensors.


Figure 1 – All-printed PEDOT:PSS and Ag/AgCl ink- based stretchable electrochemical devices.


MAY 2016


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