For the past couple of years,  John Rogers, a materials science professor at the University of Illinois, has been working on his pet-project: the Biostamp. True to its name, the device is basically a tiny electronic stamp, no larger than a quarter, that sticks to the skin and can be worn seamlessly. The whole time, the Biostamp collects on a variety of vital signs, depending on the embedded sensor, and is powered wirelessly via your mobile phone. It can analyze chemicals in your sweat; blood pressure; UV radiation and much more. Basically, it’s transforming the way patients are monitored. In fact, it’s changing the way people, sick or not, monitor their health. Imagine wearing a Biostamp all the time and receiving a notification on your mobile phone to visit your doctor ASAP because your blood pressure has been too high in the last couple of days.

Medical checkups can be a real hassle, for both patients and doctors. First, a doctor checks your blood pressure, your temperature and so on. If the doctor sees a sort of anomaly, he’ll register you for further checks – this time on bulky equipment. Maybe an electrocardiogram for your heart or a blood test for diabetes.

The biostamp stretch like skin, includes flexible circuits, and can be powered wirelessly. The butterfly-shaped sensor monitors exposure to UV rays; the one at the center uses sensitive dyes to detect key chemicals in sweat; on the right, this sensor uses an electronic circuitry to measure blood pressure differences. Image: James Provost

Not even a decade from now, the Biostamp might become ubiquitous that simple checkups will be handled by your smartphone. You’ll only visit your doctor when you really have to. Additionally, the wealth of data the sensors pick up will help the doctor give better diagnoses, since he’ll see when exactly your health deteriorates, for how long and so on.

Rogers and colleagues first started work on the Biostamp in 2008. Since then, he’s founded a company called MC10 to market commercial health sensors. MC10 today has about 60 full-time employees, US $60 million in venture capital and corporate investment. So far, the company only has one product for sale: the Checklight – a skullcap that precisely measures the acceleration during athlete’s head impacts. For the Biostamp, corporate interest is a lot more intense. For instance, one client currently testing it and an early investor in the company is L’Oréal, the hair and skincare giant. The two companies are now working together to develop a Biostamp sensor that monitors how heat travels across the skin under the patch. Embedded inside the patch is a tiny heat generator, and a temperature sensor. The patch could track changes in hydration as people use its products over time and more general changes as the skin ages.  “I would love to see a beauty patch on someone’s body give them skin-care recommendations,” Guive Balooch, global vice president in charge of new technologies for L’Oréal, who learned about Rogers and his work after reading of his papers.

Assortment of Biostamps. Image: Randi Klett

Other groups are researchers the possibility of using Biostamps to measure mental stress in air traffic controllers. When you’re stressed, the hands are a lot hotter. When this happens to the air traffic controller, small doses of a stress reliever drug is injected.

Here’s how the Biostamp is built:

The biostamp includes arrays of transistors, diodes, capacitors, inductors, LC oscillators, temperature sensors, strain gauges, an LED, an inductive coil, and a simple antenna. Image: Randi Klett

“A Biostamp is built out of stretchable circuits supported by an extremely thin sheet of rubber. To make these circuits, Rogers and his colleagues in Illinois start by fabricating their transistors, diodes, capacitors, and other electronic devices on wafers of any common semiconductor material. They typically use silicon but could also use gallium arsenide or gallium nitride. These are not ordinary semiconductor wafers; they’re kind of like the Oreo cookie of semiconductor wafers. They have a thin top layer of semiconductor material, a thicker bottom layer of the same material that acts as a rigid support during manufacture, and a sacrificial layer of a different material in between. In the case of a silicon wafer, this sacrificial layer is silicon dioxide. After the device manufacture is complete, a chemical bath eats away that central layer and frees the thin top layer.

Then a stamp made of soft silicone presses onto the wafer. Raised areas on the stamp lift away selected electronic devices in the same way a rubber stamp picks up ink from a stamp pad. After picking up the devices, the silicone stamp deposits them onto a temporary substrate, usually a plastic-coated glass plate. This plate then goes through a standard photolithography process that connects the devices with copper conductors in the form of serpentine coils, which make the connections stretchable.

The next step is to transfer the interconnected devices from the plastic-coated glass onto what will go to the consumer—a thin sheet of rubber already attached to a plastic backing sheet, with a layer of adhesive in between. To do this, a machine pushes the rubber against the array of devices and coils that are still clinging to the plastic-coated glass. A final chemical bath dissolves the plastic between the electronic circuits and the glass, leaving the circuits attached to the rubber. And the last step happens when the Biostamp gets into the hands of the user—who exposes the adhesive and sticks the rubber-backed electronics onto the skin,” writes Tekla Perry for Spectrum IEEE.

For the moment, there are some clinical trials involving the Biostamp in the United States and Europe. Commercial versions will become available late this year.