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How miniaturized electronic devices can be used as medical therapeutics

​Inspired by personal experience, an engineer pioneers the development of ‘electroceuticals’ that can dispense treatments or monitor functions deep inside the body.

Ada Poon is developing tiny electronic devices to dispense treatments or monitor functions deep inside the body. | Photo courtesy of Poon Lab

Twice in her career, Ada Poon has experienced the vulnerability of the human body in ways that led her to become an associate professor of electrical engineering and a pioneer in research to develop electronic therapies to heal the body from within.

The first incident occurred while she was an undergraduate studying computer programming in Hong Kong. Poon spent so many hours writing code that she developed intense shoulder pain. Her doctor advised her to switch to a field that involved less keyboarding, and when she arrived at the University of California, Berkeley, to attend graduate school, Poon shifted her focus to the study of information theory for wireless communications.

After earning her PhD in 2004, Poon worked in industry for a while, developing processors for radios and wireless HDMI connections to link TVs and set-top boxes.

Then came a second and more serious shock when Poon’s father was stricken with cancer. Chemotherapy seemed to hurt him more than it helped, and to her great sadness he did not survive. “This incident let me realize how helpless a patient could be,” Poon recalls. It also led to some soul searching. “I didn’t want to spend my career just to build gadgets for entertainment or for leisure,” she says.

So in 2008 Poon joined the Stanford faculty determined to apply the principles of electrical engineering to discovering new ways to fight disease. “At that time I knew nothing about biology,” she recalls with a quiet laugh. “Now that I think about it, I was very brave.”

But Poon’s academic training, her work in industry and her life experience had given her a needs-based approach to research. The problem with chemotherapy or any drug therapy is the lack of active control and response to feedback. Once the infusion or pill goes into the patient’s body, all the doctor can do is wait and watch and perhaps adjust the dose or the frequency. These therapies can’t self-regulate based on feedback from the body in order to increase or decrease their effects in accordance with the patient’s needs. Adding control and feedback are what electrical engineers are good at.

Electronic devices, Poon knew, could be programmed to respond to the body’s feedback and modulate their own effects after being implanted in the body, thus offering the potential for a closed-loop system that could improve therapeutic outcomes. Researchers have come up with a term for this emerging category of devices – electroceuticals.

But when Poon started her research it was easier to say electroceutical than it was to build one. Size was a problem. Pacemakers, cochlear implants and other devices designed to work in the human body were too bulky to work locally on, say, nerve fibers.

Power was an even bigger obstacle to creating electroceuticals. Engineers already knew how to miniaturize the electronics in any device. But batteries were difficult to shrink, and running wires from the outside of the body to a device implanted within would be risky and impractical.

Wireless power transfer technologies did exist for uses such as the electric toothbrush. But wireless power transfer to a miniaturized medical device implanted deep inside the body seemed impossible. The prevailing assumption was that the efficiency would be too low to be practical.

Both Poon’s education in information theory and mathematics and her work experience in wireless communications pushed her to reject the assumptions that had held back the development of electronic medical devices. “That’s what I think engineering is about,” Poon says. “There are certain needs, and we expand our skill set to solve the problem.”

Over a period of several years, working alongside biologists in an interdisciplinary setting, Poon started from scratch and discovered how to safely and efficiently beam electromagnetic energy into the body. This has enabled her team to create tiny electronic devices that can be wirelessly powered or recharged from outside the body.

One minuscule prototype is designed to swim through a patient’s circulatory system to deliver drugs or perform tests. Another is a pacemaker smaller than a grain of rice. It can be recharged when necessary by holding a credit-card-sized power transmitter up to the chest.

Currently, Poon is helping to design a wireless biosensor that could continuously monitor the drug concentration in the bloodstream of chemotherapy patients, so that the dose can be self-regulated and save patients from excessive exposure to the toxic chemicals.

Poon credits these achievements to the fact that researchers from many fields feel comfortable working together. “We can start to solve this kind of problem because we’re of the generation that accepts multidisciplinary thinking,” she says.

Poon recently outlined one of her new research efforts at a conference organized by Stanford’s SystemX Alliance for academic and industrial cooperation. It involves a tiny neuromodulator chip installed on the nerves that regulate the heart and brain. The chip is powered and directed by a disposable skin patch. This electroceutical system would be intended to lower blood pressure or adjust heart rate, and allow the patient to apply a new power and control patch as needed.

“Imagine instead of a bottle of pills, it becomes a box of patches,” she says.

Poon envisions that companies will eventually turn such research into products for all sorts of uses from controlling blood pressure to relieving pain, but she wants to stick to research and leave the commercialization to others. “I’m more interested in the science part,” Poon says. “I would like to expand myself into more than a technician to the medical doctors. I myself want to participate in exploring parts of the pathways, understanding the human body.”

Indeed, her next big goal is to help map the nervous system the way electrical engineers might diagram a circuit.

Better understanding the intricacies of the body’s electrochemical control network would allow engineers to develop therapies to treat the most complex diseases and guide their efforts to implant electroceuticals at optimal locations in the body.

Poon also has found other ways to have an impact, such as serving as a role model for girls interested in science and engineering.

Last summer, through a program called Girlz Gone Wireless, she taught 22 high schoolers how to make their own cellphone chargers and wireless speakers. “I hope they’ll experience fewer hurdles with studying electrical engineering or any other engineering field,” Poon says.

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This article is part of our Stanford Engineering Magazine