The sensors can be drawn on almost any surface, even a leaf. (Amay Bandodkar)
Diabetes runs in Amay Bandodkar’s family. He remembers watching his grandmother, who suffered from Type 2 diabetes, draw blood from her finger every few hours for glucose tests. The process got harder as she grew older, and in her final years Bandodkar says it hurt to watch.
“She was really skinny, and sometimes she would have to prick over and over to find a vein,” he recalls. “I could see the pain she was in.”
Now a graduate student in the engineering department at UC San Diego, Bandodkar and his adviser, Professor Joseph Wang, have developed products that could have spared her pain: glucose sensors that are cheap, non-invasive, and renewable, applied using a regular ballpoint pen or stuck on like a temporary tattoo.
These new sensors make testing blood sugar as easy as signing your name, and have the potential to revolutionize a multibillion dollar industry.
The Glucose Gold Rush
The glucose self-monitoring industry has exploded as Type 2 diabetes proliferated over the past thirty years. Diabetes diagnoses doubled between 1980 and 2011, while sales of glucose monitoring products grew by over 12 percent annually from 1994 to 2006. Today, the industry is worth over $8 billion.
“You have to throw [the strips] away,” Bandodkar says. “If we could make a reusable sensor that would be one way to reduce the cost.”
So, he and Wang set out to find a renewable sensor. The bio-catalytic enzymatic roller pens they came up with (“biocatalytic pens” for short) could be the next generation of glucose testing for the masses: reusable, customizable, and cheap.
The biocatalytic pen uses ink with glucose-oxidase, an enzyme that reacts selectively with glucose.
A sensor can be applied right onto a patient’s skin using a temporary tattoo, and the glucose oxidase will react with glucose just under their skin. The reaction generates an electric current that a chip, stuck onto their skin, reads and transmits to a laptop via Bluetooth. Or, a pen can be used to draw a renewable sensor onto an electrode. In this case the patient would still supply a drop of blood for testing on the electrode.
One pen can generate 500 sensors, and the accuracy of the glucose measurements in the pen and tattoo methods are already comparable to the glucose strips in use today.
There are still some challenges to overcome, mostly in the stability and storage of the ink (which so far only keeps for three weeks in an extra-cold refrigerator), but Bandodkar will begin working with doctors in the next few months on a large-scale human trial.
He’s not the only one looking to shake up the glucose monitoring status quo.
Dexcom, also based in San Diego, has a system using a tiny wire inserted under a patient’s skin that make continuous glucose measurements. Google is even getting in on the game, with a smart contact lens it’s developing with pharma giant Novartis that would take and transmit continuous glucose measurements.
But the comparatively low-tech pens and tattoos are much cheaper than these methods, which Bandodkar hopes will help make life easier for diabetes patients who now rely on glucose testing strips.
The bio-ink technology also has a host of other applications, because ink could be made for almost any chemical that reacts with an enzyme, and drawn on any surface. Bandodkar and Wang have formulated an ink to measure levels of common air pollutants that can be drawn onto tree leaves, or other natural surfaces, to cheaply monitor local pollution.
The sneakiness of a sensor hidden in a ballpoint pen also has military utility.
“For defense, you wouldn’t want your enemy to know you [deployed] a chemical sensor,” Bandodkar says. An armed person could take the pen and draw a sensor onto any surface to stealthily detect chemical weapons.
Some Science is Personal
But among all the exciting applications of the pens, glucose-sensing remains Bandodkar’s priority, and not for the potential commercial gains. His grandmother wasn’t the only one in his family to suffer from diabetes: his mom also suffers from Type 2 diabetes.
“When I told my mom I was working on this, she was so happy,” he says. The potential to help her and millions of others keeps him motivated, but he doesn’t let personal investment cloud his scientific rigor.
“You have your emotional attachment, and on the other side you have your scientific yes or no, is it working or not,” he says.
So far, the answer seems to be a definitive ‘yes.’ More work needs to be done, but glucose-sensing pens may be only two or three years away from commercial availability. It’s too late to help Bandodkar’s grandmother, who passed away several years ago, but he can still help his mother — and 400 million others — save their blood and money.
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