Inside Dental Technology
Jul/Aug 2012
Volume 3, Issue 7

Tomorrow’s Tooth Doctor

Wireless bacteria detection device applied to natural teeth or crowns may some day remotely monitor health status.

Michael McAlpine, lead investigator at the McAlpine Research Group, is always thinking of ways to make people’s lives better and safer. He and his team of researchers at Princeton University work with nano-materials and bio-nano interfaces to create devices that change the way we think about our approaches in medicine as well as energy. In 2008, as a new assistant professor at Princeton, McAlpine began wondering if there was a way to harvest enough power from the action of the lungs as people inhale and exhale or from the forces generated by physical movement to power an implanted pacemaker. If that were the case, then the batteries powering the pacemaker would not need to be surgically replaced every few years, saving patients from additional invasive surgeries and spending untold amounts of money. So he set about developing a flexible material that produces energy when subjected to mechanical pressure.

Today, his focus is on further developing a graphene-based material that he believes will revolutionize how we detect the presence of harmful bacteria when placed on a variety of surfaces including on the surface of a natural tooth or crown in the mouth. The chemical sensor is a unique combination of biomaterials imprinted with a radio-frequency nano-sensor that can wirelessly and remotely communicate the presence of pathogenic bacteria (Figure 1 and Figure 2). “We have been able to show that when placed on a natural tooth, the device will react to the presence of bacteria,” said McAlpine. “Because teeth come into contact with both the breath and saliva, we consider the mouth as a rich source of biomedia, and if one day we can actually detect and distinguish diseases, this device would act as a non-invasive and continuous monitor of a patient’s health status.”

The graphene layer on the sensor is a single carbon atom thick and imprinted with a wireless coil for transmission and readout. Carbon is a highly conductive material so when the bacteria electrostatically interact with the graphene it produces a change in the graphene’s conductance. Once placed, the hypersensitive nano-sensor is able to detect bacteria at the single cell level. “Because the device is a single atom thick, the ability to adhere the device to biomaterials such as teeth and skin is very good,” said McAlpine. The sensor is delivered on a water-soluble silk backing that is dissolved once placed, much like a child would apply a temporary tattoo. The sensor is less than a nanometer thick and cannot be detected by feel nor can it be seen with a microscope. And it is the first time such a detection device has been interfaced directly with biological tissue.

McAlpine views the new material as a tailorable platform with a wide range of uses from detecting harmful foodborne bacteria such as E.coli and hospital sanitation monitoring to detecting harmful bacteria in drinking water in developing countries. “Anywhere disease may be present and detection of disease to prevent harm to humans is a welcome advancement,” said McAlpine.

The next challenge for McAlpine and his team of researchers is tweaking the sensor to identify and distinguish the bacteria it senses. He believes that in another year they will have a good start on accomplishing that goal, and the device can be readied for clinical trials. One day, perhaps in the not so distant future, driving to the doctor’s office for your annual checkup or for diagnosis of a physical complaint will be a thing of the past. Instead, your physician will notify you via your Smartphone, or other more sophisticated electronic communication medium, to pick up a prescription at the local drug store long before you ever notice any symptoms of the ailment. And, your annual physical will be a mere consultive meeting with your doctor to review the sensor’s findings over the past year and set a course of action if needed. “It’s a tiny device with extraordinary properties,” said McAlpine.

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