A team of researchers from the IIT-Italian Institute of Technology in Milan has discovered that a substance in everyday toothpaste could be used in the making of edible electronics and have used it to create a “toothpaste-based transistor” for healthcare.

According to the team, the nano-device could specifically be used in the manufacture of future “smart pills” that will, once inside the body, track people’s health and then harmlessly break down.

Source: IIT-Italian Institute of TechnologySource: IIT-Italian Institute of Technology

A substance called copper phthalocyanine — which is the blue pigment found in many commercial toothpastes — possesses crystals that serve as a whitening agent that coats the teeth as well as acting as an “optical filter” that reflects light in a way that makes the teeth appear whiter. Throughout the day, the copper phthalocyanine is slowly removed by saliva and eventually enters the human body; a finding, the researchers suggest means that the average person unknowingly consumes one milligram of copper phthalocyanine every time they brush their teeth.

Meanwhile, the team also determined that the chemical structure of the copper phthalocyanine allows for charge conduction within its crystals, which reportedly suggests that the material can carry electrical current. This, according to the team, makes it an ideal material for semiconductors. Likewise, because the pigment is edible, it could also potentially be used to power tiny electronic devices inside human bodies.

To test this approach, small amounts of copper phthalocyanine were incorporated into an edible circuit, thereby creating a transistor that operates on a low voltage. The team opted to build the circuits on a stable base of ethylcellulose substrate, which is often used in pharmaceutical and food manufacturing industries.

Additionally, the electrical connections featured on the circuits were printed using inkjet technology and the ink used contains a solution of gold particles — which are also an excellent conductor of electricity.

Because all transistors consist of a “gate,” for regulating the flow of current, the researchers based their edible transistor’s gate on chitosan, which is a natural polymer made from the shells of crustaceans like crabs and serves as a “gelling agent.”

The team explained that when the material is used to form an electrolytic gel, it produces a conductive material that can control the flow of electricity. Specifically, when a low voltage — less than 1 V — is applied to the gate, it can control the flow of current through the transistor, enabling it to turn on or off.

The team believes that these edible transistors could potentially be used in smart pills for monitoring vital signs, detecting diseases early, delivering targeted treatments and controlling food quality, among other use cases.

An article detailing the findings, “A Fully Edible Transistor Based on a Toothpaste Pigment,” appears in the journal Advanced Science.

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