For centuries, humans embraced body modification and the idea of human-device symbiosis1. Color-changing tattoo is one of the advancing technology which is the combination of biotechnology with traditional methods in tattoo artistry. Over the last 30 years, tattoos have been seen more commonly in Western culture and nowadays, approximately 24% of Americans have at least one tattoo5. Tattooing is a ubiquitous body modification that is made because of several reasons. Some people prefer it to cover up scar tissues whereas others may prefer it just to be more aesthetic. Ink or dye pigments are injected into the dermis during the tattooing process. Many studies are present in the literature about biosensors in the form of a tattoo.
According to the research, biosensors are in the form of tattoos which means they have been injected into the dermis2. Inserting a sensor inside the dermis as a tattoo in order to be in contact with interstitial fluid (ISF) provides spectacular insight for monitoring biomarkers. Interstitial fluid is the body fluid that is found between blood vessels and cells. It is composed of various components and it encloses cells with some molecules such as water, amino acid, sugar, fatty acids, and neurotransmitters. It is also responsible for transportation, intercellular communication, and the expulsion of metabolic waste3. Glucose, sodium, albumin, oxygen, cortisol, lactate, and pH can be monitored as different physiological biomarkers.
In response to the alterations of the biomarkers present in the interstitial fluid, color changes could be displayed1. When a change in pH level occurs, it is detected by biosensor ink, and color shifts from pink to purple with an increase in pH level. If the sodium amount increases in the blood, a vibrant green color can be observed under UV light. When the blood glucose level rises, the sensor alters its color and shifts from blue to brown. This can provide significant insights into the health status and can influence the individual life who suffers from Diabetes4. Scientists believe that their glucose-sensing tattoo could be extremely beneficial for patients who have diabetes and need to monitor glucose levels with pin-prick blood tests every day.
The outcome of this research also proved that skin provides information related to the body’s metabolism, which can be evinced by wearable biosensors. For diagnosing and health monitoring, tattoos could be seen as an up-and-coming platform. Biosensors may be an effective tool to be used in medical diagnostics. However, products are still in the proof-of-concept stage but the idea is innovative, and promising, and will be held in the future.
References:
- Vega K, Jiang N, Liu X, et al. The dermal abyss: Interfacing with the skin by tattooing biosensors. In: Proceedings – International Symposium on Wearable Computers, ISWC. Vol Part F130534. ; 2017. doi:10.1145/3123021.3123039
- Yetisen AK, Moreddu R, Seifi S, et al. Dermal Tattoo Biosensors for Colorimetric Metabolite Detection. Angew Chemie – Int Ed. Published online 2019. doi:10.1002/anie.201904416
- Stewart RH. A Modern View of the Interstitial Space in Health and Disease. Front Vet Sci. Published online 2020. doi:10.3389/fvets.2020.609583
- Kim J, de Araujo WR, Samek IA, et al. Wearable temporary tattoo sensor for real-time trace metal monitoring in human sweat. Electrochem commun. 2015;51:41-45. doi:10.1016/j.elecom.2014.11.024
- Tattoo Inks for Optical Biosensing in Interstitial Fluid Martalu D. Pazos,Yubing Hu,Yuval Elani,Kathryn L. Browning,Nan Jiang,Ali K. Yetisen https://doi.org/10.1002/adhm.202101238>
FigureReference: Vega K, Jiang N, Liu X, et al. The dermal abyss: Interfacing with the skin by tattooing biosensors. In: Proceedings – International Symposium on Wearable Computers, ISWC. Vol Part F130534. ; 2017. doi:10.1145/3123021.3123039
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