Tag Archives: Siheng Sean You

Plug me in: how to power up ingestible and implantable electroncis

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From time to time I’ve featured ‘vampire technology’, a name I vastly prefer to energy harvesting or any of its variants. The focus has usually been on implantable electronic devices such as pacemakers and deep brain stimulators.

In this February 16, 2021 Nanowerk Spotlight article, Michael Berger broadens the focus to include other electronic devices,

Imagine edible medical devices that can be safely ingested by patients, perform a test or release a drug, and then transmit feedback to your smartphone; or an ingestible, Jell-O-like pill that monitors the stomach for up to a month.

Devices like these, as well as a wide range of implantable biomedical electronic devices such as pacemakers, neurostimulators, subdermal blood sensors, capsule endoscopes, and drug pumps, can be useful tools for detecting physiological and pathophysiological signals, and providing treatments performed inside the body.

Advances in wireless communication enable medical devices to be untethered when in the human body. Advances in minimally invasive or semi-invasive surgical implantation procedures have enabled biomedical devices to be implanted in locations where clinically important biomarkers and physiological signals can be detected; it has also enabled direct administration of medication or treatment to a target location.

However, one major challenge in the development of these devices is the limited lifetime of their power sources. The energy requirements of biomedical electronic devices are highly dependent on their application and the complexity of the required electrical systems.

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Berger’s commentary was occasioned by a review article in Advanced Functional Materials (link and citation to follow at the end of this post). Based on this review, the February 16, 2021 Nanowerk Spotlight article provides insight into the current state of affairs and challenges,

Biomedical electronic devices can be divided into three main categories depending on their application: diagnostic, therapeutic, and closed-loop systems. Each category has a different degree of complexity in the electronic system.

… most biomedical electronic devices are composed of a common set of components, including a power unit, sensors, actuators, a signal processing and control unit, and a data storage unit. Implantable and ingestible devices that require a great deal of data manipulation or large quantities of data logging also need to be wirelessly connected to an external device so that data can be transmitted to an external receiver and signal processing, data storage, and display can be performed more efficiently.

The power unit, which is composed of one or more energy sources – batteries, energy-harvesting, and energy transfer – as well as power management circuits, supplies electrical energy to the whole system.

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Implantable medical devices such as cardiac pacemakers, neurostimulators and drug delivery devices are major medical tools to support life activity and provide new therapeutic strategies. Most such devices are powered by lithium batteries whose service life is as low as 10 years. Hence, many patients must undergo a major surgery to check the battery performance and replace the batteries as necessary.

In the last few decades, new battery technology has led to increases in the performance, reliability, and lifetime of batteries. However, challenges remain, especially in terms of volumetric energy density and safety.

Electronic miniaturization allows more functionalities to be added to devices, which increases power requirements. Recently, new material-based battery systems have been developed with higher energy densities.

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Different locations and organ systems in the human body have access to different types of energy sources, such as mechanical, chemical, and electromagnetic energies.

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Energy transfer technologies can deliver energy from outside the body to implanted or ingested devices. If devices are implanted at the locations where there are no accessible endogenous energies, exogenous energies in the form of ultrasonic or electromagnetic waves can penetrate through the biological barriers and wirelessly deliver the energies to the devices.

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Both images embedded in the February 16, 2021 Nanowerk Spotlight article are informative. I’m particularly taken with the timeline which follows the development of batteries, energy harvesting/transfer devices, ingestible electronics, and implantable electronics. The first battery was in 1800 followed by ingestible and implantable electronics in the 1950s.

Berger’s commentary ends on this,

Concluding their review, the authors [in Advanced Functional Materials] note that low energy conversion efficiency and power output are the fundamental bottlenecks of energy harvesting and transfer devices. They suggest that additional studies are needed to improve the power output of energy harvesting and transfer devices so that they can be used to power various biomedical electronics.

Furthermore, durability studies of promising energy harvesters should be performed to evaluate their use in long-term applications. For degradable energy harvesting devices, such as friction-based energy harvesters and galvanic cells, improving the device lifetime is essential for use in real-life applications.

Finally, manufacturing cost is another factor to consider when commercializing novel batteries, energy harvesters, or energy transfer devices as power sources for medical devices.

Here’s a link to and a citation for the paper,

Powering Implantable and Ingestible Electronics by So‐Yoon Yang, Vitor Sencadas, Siheng Sean You, Neil Zi‐Xun Jia, Shriya Sruthi Srinivasan, Hen‐Wei Huang, Abdelsalam Elrefaey Ahmed, Jia Ying Liang, Giovanni Traverso. Advanced Functional Materials DOI: https://doi.org/10.1002/adfm.202009289 First published: 04 February 2021

This paper is behind a paywall.

It may be possible to receive a full text PDF of the article from the authors. Try here.

There are others but here are two of my posts about ‘vampire energy’,

Harvesting the heart’s kinetic energy to power implants (July 26, 2019)

Vampire nanogenerators: 2017 (October 19, 2017)

Human-machine interfaces and ultra-small nanoprobes

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We’re back on the cyborg trail or what I sometimes refer to as machine/flesh. A July 3, 2019 news item on ScienceDaily describes the latest attempts to join machine with flesh,

Machine enhanced humans — or cyborgs as they are known in science fiction — could be one step closer to becoming a reality, thanks to new research Lieber Group at Harvard University, as well as scientists from University of Surrey and Yonsei University.

Researchers have conquered the monumental task of manufacturing scalable nanoprobe arrays small enough to record the inner workings of human cardiac cells and primary neurons.

The ability to read electrical activities from cells is the foundation of many biomedical procedures, such as brain activity mapping and neural prosthetics. Developing new tools for intracellular electrophysiology (the electric current running within cells) that push the limits of what is physically possible (spatiotemporal resolution) while reducing invasiveness could provide a deeper understanding of electrogenic cells and their networks in tissues, as well as new directions for human-machine interfaces.

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The Lieber Group at Harvard University provided this image illustrating the work,

U-shaped nanowires can record electrical chatter inside a brain or heart cell without causing any damage. The devices are 100 times smaller than their biggest competitors, which kill a cell after recording. Courtesy: University of Surrey

A July 3, 2019 University of Surrey press release (also on EurekAlert), which originated the news item, provides more details about this UK/US/China collaboration,

In a paper published by Nature Nanotechnology, scientists from Surrey’s Advanced Technology Institute (ATI) and Harvard University detail how they produced an array of the ultra-small U-shaped nanowire field-effect transistor probes for intracellular recording. This incredibly small structure was used to record, with great clarity, the inner activity of primary neurons and other electrogenic cells, and the device has the capacity for multi-channel recordings.

Dr Yunlong Zhao from the ATI at the University of Surrey said: “If our medical professionals are to continue to understand our physical condition better and help us live longer, it is important that we continue to push the boundaries of modern science in order to give them the best possible tools to do their jobs. For this to be possible, an intersection between humans and machines is inevitable.

“Our ultra-small, flexible, nanowire probes could be a very powerful tool as they can measure intracellular signals with amplitudes comparable with those measured with patch clamp techniques; with the advantage of the device being scalable, it causes less discomfort and no fatal damage to the cell (cytosol dilation). Through this work, we found clear evidence for how both size and curvature affect device internalisation and intracellular recording signal.”

Professor Charles Lieber from the Department of Chemistry and Chemical Biology at Harvard University said: “This work represents a major step towards tackling the general problem of integrating ‘synthesised’ nanoscale building blocks into chip and wafer scale arrays, and thereby allowing us to address the long-standing challenge of scalable intracellular recording.

“The beauty of science to many, ourselves included, is having such challenges to drive hypotheses and future work. In the longer term, we see these probe developments adding to our capabilities that ultimately drive advanced high-resolution brain-machine interfaces and perhaps eventually bringing cyborgs to reality.”

Professor Ravi Silva, Director of the ATI at the University of Surrey, said: “This incredibly exciting and ambitious piece of work illustrates the value of academic collaboration. Along with the possibility of upgrading the tools we use to monitor cells, this work has laid the foundations for machine and human interfaces that could improve lives across the world.”

Dr Yunlong Zhao and his team are currently working on novel energy storage devices, electrochemical probing, bioelectronic devices, sensors and 3D soft electronic systems. Undergraduate, graduate and postdoc students with backgrounds in energy storage, electrochemistry, nanofabrication, bioelectronics, tissue engineering are very welcome to contact Dr Zhao to explore the opportunities further.

Here’s a link to and a citation for the paper,

Scalable ultrasmall three-dimensional nanowire transistor probes for intracellular recording by Yunlong Zhao, Siheng Sean You, Anqi Zhang, Jae-Hyun Lee, Jinlin Huang & Charles M. Lieber. Nature Nanotechnology (2019) DOI: https://doi.org/10.1038/s41565-019-0478-y Published 01 July 2019

The link I’ve provided leads to a paywall. However, I found a freely accessible version of the paper (this may not be the final published version) here.