Table of contents

• What are E-tattoos?

• Role of E-tattoos in healthcare

• E-tattoos for heart diagnostics

• Design of E-tattoos for heart diagnostics

• Monitoring blood pressure using graphene electronic tattoos

• Advantages and Disadvantages of E-tattoos

• Take-Home Points

• FAQ on E-Tattoos For Heart Diagnostics and Heart Monitoring

What are E-tattoos?

E-tattoos or Electronic tattoos are skinny rubber patches with a flexible circuit, which can be easily placed on the skin to keep track of the vitals and other functions within the human body. The rubber patch's flexible circuit can generate an electric charge on its own and helps to monitor and send the data in real time to the connected devices. 

E-tattoos use graphene, gold nanorods, or other polymers with rubber backing and cause minimal discomfort when placed. Electronic tattoos are adaptable to various skin textures, and their flexibility makes them move with any skin movement and does not interrupt data transmission.

Role of E-tattoos in healthcare

Though E-tattoos have numerous applications, the primary field of application is healthcare. The high elderly population and increased rate of people diagnosed with chronic diseases have resulted in a high demand for point-of-care diagnosis and real-time medical monitoring. The conventional diagnostic methods require visits to clinics or hospitals, costly medical diagnostic tools, and the help of highly trained personnel, which resulted in the evolution of easy wearable devices like digital tattoos or E-tattoos.

E-tattoos are similar to temporary tattoos, but these non-invasive medical tattoos allow continuous monitoring of heartbeat, blood pressure, blood sugar level, muscle activity, etc., for days without discomfort. They enable easy diagnosis and post-treatment monitoring, thus improving the quality and effectiveness of medical services.

E-tattoos for heart diagnostics

Heart diseases are a major cause of death globally. Most of the time, people fail to realize that their heart health has weakened. The standard tool doctors use to monitor heart health is the ECG or electrocardiograph, but it requires a clinical setup. Thus the demand for new tools to monitor heart health and record data conveniently without frequent visits to the clinic or hospital also increased. It leads to the development of comfortable and wearable technologies like E-tattoos. These medical tattoos are powered remotely by external devices like smartphones or computers, giving access to the user and health experts to the recordings and readings made by the e-tattoo. 

The lightweight and stretchable E-tattoos are placed on the chest to monitor heart health through electrocardiogram (ECG) and seismocardiogram (SCG) readings. The standard E-tattoo device has two sensors, one made of PET plastic (polyethene terephthalate) and gold and the other made of PVDF (piezoelectric polyvinylidene fluoride). PVDF is capable of producing electrical charge when subjected to mechanical stresses. 

EGs are a standard recording method of electrical activity rates produced each time the heart beats, while seismocardiography (SCG) is a measurement technique that uses chest vibrations related to heartbeats. The combined SCG and ECG recordings allow for determining the health status of the heart accurately. This way, healthcare experts can observe and identify critical heart health conditions like heart arrhythmia and even monitor heart activities in premature newborns. E-tattoos have undergone several advancements over the last decade so that newly developed E-tattoos can alert medical teams and even call an ambulance when a person's heart health becomes critical.

Design of E-tattoos for heart diagnostics 

Advancements in 3-D printing and circuit printing have a significant role in developing heart health monitoring digital tattoos. Most E-tattoos use metal films, silicon membranes, nano-particle-based inks, and graphene with rubber packing. 

E-tattoos can be damped to the skin, similar to a child’s decorative tattoo. The device's design is such a way that it can follow any shape and does not interfere with motion or body movements. Once E-tattoo is damped to the skin, the tiny electrodes in the flexible circuit start to record the information about vitals and other essential biomarkers of the user, process it, and send it to the connected devices.

Graphene electronic tattoos (GET) are the most popular E-tattoo for heart health monitoring. Graphene electronic tattoos have a thickness of around 463 nm, more than 40 percent stretchability, and an optical transparency of 85 percent. At the same time, graphene electronic tattoos are reliable and provide excellent comfort and mobility.

The graphene electronic tattoo's design makes it easy to laminate on the skin and adapt to the skin morphology by van der Waals forces. The open mesh design of the graphene electronic tattoos makes its stiffness negligible and breathable. A bare graphene electronic tattoo without any attachment medium can stick to the skin's surface for hours without fracture or stripping off. A liquid-bandaged graphene electronic tattoo stays functional for several days on the skin. This medical tattoo can successfully record ECG, electroencephalogram (EEG), EMG (electromyogram), body temperature, etc. 

Monitoring blood pressure using graphene electronic tattoos

High blood pressure is a major risk factor associated with heart health. Around 50 percent of cardiovascular diseases are accountable to high blood pressure. Measuring blood pressure with standard devices gives blood pressure at a particular point, which depends on several factors, including the patient's mood. Thus continuous blood pressure monitoring for a while is needed to understand the complete picture and functioning of the body. 

Keeping track of blood pressure and other vitals is very difficult outside a clinical setup, though wearable devices like smartwatches and fitness gadgets are an option. A graphene sensor closeted in a sticky material can keep track of the blood pressure and other vitals for several hours without causing discomfort to the patient. The medical tattoo provides accurate data even if the patient is under stress, exercising, or sleeping. The graphene E-tattoo works by firing an electrical current into the skin and measures the value of how the body reacts to it, which is known as bioimpedance. 

Advantages and Disadvantages of E-tattoos

Advantages of E-tattoos

Ease of use - They are tiny temporary tattoos capable of recording vitals and other bodily functions without interrupting body movements. They do not require external charging or replacement of batteries and the help of experienced personnel to collect the data. The health care experts and the user can easily access the data through a smartphone or a computer.

Accurate data- Most wearable devices do not integrate into the user’s skin like an E-tattoo. Thus, E-tattoos can produce more accurate and instant data than other devices.

Design - E-tattoos are temporary, lightweight, flexible, waterproof, and easily adaptable devices. The flexible circuit can generate an electric charge on its own and helps monitor, process, and send health data in real-time to the connected devices. 

Continuous monitoring for several hours to days- Continuous monitoring of the body functions and vitals in patients with severe health conditions like cardiovascular problems is made easy with the help of medical tattoos. E-tattoos for heart health monitoring quickly identify any critical health situation of the user and alert the user and the health experts immediately, improving the quality and effectiveness of medical services.

Environment friendly- E-tattoos are environmentally friendly and do not end up as waste material like most other wearable devices.

Disadvantages of E-tattoos

E-tattoos have a wide range of applications and advantages. At the same time, it has some drawbacks too.

E-tattoos are temporary- The present-day E-tattoos last for 1-2 weeks. The last decade has seen several advancements and research on E-tattoos, but the technology for permanent medical tattoos does not exist at the moment. However, the temporary nature of E-tattoos is an advantage to people who do not want a permanent E-tattoo.

Privacy and security issues- E-tattoos for heart diagnostics uses external devices like smartphones or computers to access the E-tattoo for heart health monitoring. While this is a convenient option, it also poses a high risk of leak of medical data into the wrong hands. 

Take-Home Points

• Progress in biomedical engineering has met the need for a more accurate, real-time, and convenient point-of-care diagnosis and medical monitoring through medical tattoos or E-tattoos. 

• The temporary E-tattoo for heart diagnostics monitors and records health data and sends it to externally connected devices. Thus, E-tattoos enable the user and the health experts to keep track of heart health and quickly identify any critical cardiac issues.

• Progress in the design and function of E-tattoos occurred over the years, but at the moment, the technology for permanent medical tattoos does not exist.

References

Evolution of Wearable Devices with Real-Time Disease Monitoring for Personalized Healthcare

Fabrication, characterization, and applications of graphene electronic tattoos

Intelligent tattoos, patches, and other wearable biosensors