Getting to the heart of healthcare

Diagnosing and treating matters of the heart have come a long way. While an electrocardiogram (ECG, see fig. 1) provides information about the functioning of this vital organ, implantable medical devices such as the pacemaker focus on cardiac rhythm management, and are used to treat irregular heart rhythms like bradycardia (beating too slow) or tachycardia (too fast).

Today’s implantable devices provide therapy to treat numerous conditions. As with commercial portable products, they too share the need to reduce size, weight, and power. Thus, there is a growing need to design miniature Integrated Circuits (ICs) for electro-medical and electro-sensor applications.

Subrahmanyam Boyapati, a research scholar with the IITB-Monash Research Academy, is working on a project to design precisely such ICs—with high Electro Magnetic Interference (EMI) immunity.

The Academy is a Joint Venture between IIT Bombay and Monash University, and fosters research partnerships between Australia and India. Research is conducted by scholars like Subrahmanyam in both countries, whilst studying for a dually-badged PhD from both organisations.

Says Subrahmanyam, “Biomedical signals are operated at low frequencies with signal amplitudes of few microvolts. At lower frequencies, however, the effect of Electro Magnetic Interference is high. Hence, designing highly EMI-immune integrated circuits is promising for research. The aim of my project is to model and design, optimise, fabricate and test highly EMI-immune integrated OpAmp circuits for versatile medical and sensor applications.”

He is undertaking this project under the supervision of Prof Maryam Shojaei Baghini and Dr Jean-Michel Redoute, and is supported by the Prime Minister’s Fellowship Scheme for Doctoral Research, a joint initiative of CII and Science and Engineering Research Board (SERB), and Industry Partner Intel.

Figure-2 Block diagram of OpAmp

“CMOS (Complementary metal–oxide–semiconductor) Operational ampli?ers (Fig.2 ) are one of the most popular analogue building blocks. Unfortunately, they are also extremely sensitive to radio frequency (RF) disturbances conveyed to their input terminals,” explains Subrahmanyam. “The increasing presence of electronic devices in our daily lives explains the growing interest in structures that combat this sensitivity to electromagnetic interference (EMI). Due to the increasing adoption of electronic and microelectronic equipments, the immunity to electromagnetic interferences (EMIs) has become an important constraint for Integrated Circuits (IC) designers. As a consequence, IC designers have to consider EMI during the design phase; retrofitting is seldom viable, and often complex and expensive. Therefore, in recent years, EMIs have been carefully investigated, both theoretically and experimentally, in order to ?nd possible prevention methodologies, in particular in high-performance digital/analog ICs that may include several operational ampli?ers (OpAmps).”

Says Prof Murali Sastry, CEO, the IITB-Monash Research Academy, “The Academy was conceived as a unique model for how two leading, globally focused academic organisations can come together in the spirit of collaboration to deliver solutions and outcomes to grand challenge research questions facing industry and society. So far, Subrahmanyam has modeled and designed four new circuit topologies of CMOS Miller OpAmps in 0.18 um CMOS technology. These topologies have achieved a high EMI immunity (less than 5 mV over a wide range of frequencies from 1 MHz to 1 GHz) when compared to the classical Miller OpAmp in simulations and measurement results. We are sure that this research will be able to contribute significantly to building high-quality electro-medical and electro-sensor devices.”

You can’t blame Subrahmanyam’s heart for beating a little faster at this vote of confidence!