Scientists create nanotattoo that enable wireless communication without external power sources

Researchers in Istanbul have achieved a significant breakthrough in the field of biosensing technologies by developing nanotattoos capable of wireless communications without relying on external power sources such as batteries. The development, made by Kristen D. Belcastro from Yeditepe University and Onur Ergen from Istanbul Technical University, could revolutionize various biosensing applications that were previously hindered by the need for bulky power sources or wired communications.

The nanotattoos, known as backscattering-based nanotattoo sensors (BNTS), consist of two inks—a zinc oxide ink with embedded nanowires layered on top of a graphene aerogel conductive ink. These two inks are simultaneously applied to the skin using separate needles. Ergen explained that the inks bond upon contact due to the presence of some aerogel in the nanowire-containing ink, albeit in a lower ratio than in the lower layer.

The wireless communications of these devices rely on the generation of electrical signals through piezoelectric activity, which occurs as the tattoos change shape, converting mechanical energy into electrical energy. The tattoos' wireless networking infrastructure employs a smartphone to bounce signals off the tattoo and receive data, aided by a broadband modem. The researchers' recent work, published in IEEE Electron Device Letters, analyzed the range of motion, but Ergen mentioned that they are exploring numerous other use cases.

The researchers explained in their paper that the painted tag reflects some radio frequency (RF) signals it receives to establish an up-link with a smartphone reader, while the smartphone establishes a down-link with the tag. From these communication links, the smartphone continuously monitors the BNTS and processes the information using artificial intelligence algorithms.

Ergen described this communication approach, known as ambient backscattering, as similar to RFID but without the limitation of a restricted number of allowed frequencies. The researchers successfully received information from the tattoos using a broadband modem operating at 900 megahertz and 2.45 gigahertz.

Experts in the field find the wireless communications capability of the nanotattoos compelling. Dmitry Kireev, an incoming assistant professor of biomedical engineering at the University of Massachusetts-Amherst, emphasized the importance of having a passive wireless tattoo that allows access to information. Kireev previously co-created a graphene tattoo for accurately measuring blood pressure. However, he acknowledged that the wired connections required by existing tattoos pose a significant obstacle to creating a truly convenient device.

Kireev expressed his enthusiasm for the concept of entirely wireless communication, stating, "if there is an approach to do this communication entirely wirelessly, what they are on to here, it's a very interesting concept." He also noted that the layered device created by Belcastro and Ergen could contribute to advancing communications research related to graphene biosensors, which are highly popular in laboratories.

Nicholas X. Williams, the vice president of technology and product development at device startup X-Cor Therapeutics, co-created an electronic thin film similar to the researchers' device during his time as a graduate student at Duke University. Williams highlighted the potential for future customization in the sensor market if functional circuits can be directly created on the skin without relying on preprinted sensors.

Ergen revealed that their research on the tattoos extends beyond healthcare applications. One ongoing investigation focuses on using the tattoos as wireless electroencephalogram (EEG) sensors. Additionally, the researchers have explored the use of sweat sensors to collect data without the need for a battery, using backscattering technology. They expect to publish this work within the next few months.