Bioelectronics is a multidisciplinary field that combines biology and electronics to develop devices that interface with biological systems. It plays a crucial role in the healthcare industry as it enables innovations like advanced prosthetics, electronic skins (e-skins), and exoskeletons to improve the quality of life for individuals by restoring or enhancing bodily functions. This integration of biological systems with electronic devices is transforming healthcare by allowing for more personalized, efficient, and responsive treatments.

The Evolution of Bioelectronics

From Concept to Application

Bioelectronics emerged in the late 18th century with Luigi Galvani's experiments, which discovered that electricity could stimulate muscles, introducing the concept of "animal electricity." His work laid the foundation for understanding neuroelectricity. In the 1930s, electrical stimulation research led to the development of cochlear implants. The field gained momentum in the 1940s and 1950s when Alan Hodgkin and Andrew Huxley recorded action potentials in nerve cells, earning them a Nobel Prize in 1963. 1

Currently, bioelectronics in medicine is considered to be a rapidly growing market. 1 Bioelectronics is currently being applied in various areas of healthcare, including wearable devices, implantable sensors, neural interfaces, and drug delivery systems. For instance, wearable electronics like health monitors and smart textiles are used to track vital signs in real time. Similarly, implantable devices, such as neural interfaces, facilitate direct communication between the brain and external devices.

Key Technologies in Bioelectronics

The current state of bioelectronics became possible due to several advanced key technologies. For instance, flexible electronics technologies allow devices to conform to the body's contours to enhance user comfort and enable continuous monitoring. Sensors embedded within these systems can capture and relay physiological data. Similarly, biocompatible materials, like bioceramics, are compatible with the body and minimize adverse reactions.

Another important technology in this regard is additive manufacturing, specifically DIW, since it allows users to print electronic structures with biocompatible inks layer by layer with high precision, which helps develop complex biomedical devices tailored to individual patients.

Understanding Biocompatible Inks and Their Role in Bioelectronics

What Are Biocompatible Inks?

Biocompatible inks are specialized materials designed for safe interaction with biological systems which makes them significant in developing bioelectronics. These inks are typically composed of polymers, hydrogels, conductive materials like gold and silver-silver chloride, or other bio-friendly substances that can mimic the properties of living tissues, such as flexibility and conductivity. The primary role of biocompatible inks in bioelectronics is to create interfaces that can integrate smoothly with biological tissues, enabling innovations like flexible sensors, and implantable devices.

Biocompatible Inks in DIW Systems

DIW technology is an advanced additive manufacturing method used to print electrical circuits, features, patterns, and traces by extruding ink from a fine nozzle in a precise and controlled manner. DIW can print biocompatible inks onto biocompatible substrates for in- or on-body monitoring and recording of bioelectric signals. 

Moreover, DIW offers high precision and flexibility, making it ideal for creating customized biomedical solutions as it allows the users to tune various parameters, including extrusion pressure, nozzle speed, and material calibration, to tailor the printed material's properties to the specific needs of a patient.

Compatibility with Common Substrates

DIW systems are highly versatile and allow precise dispensing of various materials with differing mechanical and electrochemical properties. This adaptability makes DIW well-suited for printing onto organic polymer substrates like PEDOT:PSS, which is a combination of two distinct polymers (poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate). 

PEDOT:PSS offers excellent electrical conductivity, flexibility, and biocompatibility, making it an ideal substrate for biosensing applications. This compatibility of PEDOT:PSS with DIW helps create complex, multifunctional devices where the electrochemical behavior of this substrate enhances the functionality of printed sensors, leading to innovative biomedical solutions.

On-Body and In-Body Bioelectronics: Current Applications and Future Prospects

Over the next decade, the bioelectronic technologies market is expected to witness significant growth, projected to expand from $23.9 billion in 2024 to approximately $33.6 billion by 2029, achieving a compound annual growth rate (CAGR) of 7.0%. This growth is expected due to the rising elderly population and increasing prevalence of cardiovascular and neurological disorders. Non-invasive electroceutical devices, such as on-body bioelectronics like transcutaneous electrical nerve stimulation (TENS) devices, and in-body bioelectronics like implantable neurostimulators, are anticipated to grow at the highest rate, driven by advancements in technology and increased research and development investments. 2

On-Body Bioelectronics

On-body bioelectronics refers to electronic devices and systems that are designed to be worn directly on the skin or embedded into wearable materials to monitor, stimulate, or interact with biological processes in the human body. Wearable devices like smartwatches and fitness trackers that monitor heart rate, body temperature, and other vital signs in real time are among the most common applications of on-body bioelectronics. Similarly, smart textiles are another type of on-body bioelectronics that include fabrics integrated with electronic components that can measure biomechanical movements, making them advantageous in sports, rehabilitation, and clinical monitoring.

In-Body Bioelectronics

In-body bioelectronics, like pacemakers, cochlear implants, and neural interfaces, are implanted or inserted within the human body to monitor physiological processes, deliver therapies, or interact with biological tissues at a deeper level. For instance, neural interfaces enable direct communication between the brain and external devices, providing a unique approach to treating conditions like Parkinson's disease and epilepsy. 

Multifunctional Bioelectronics

Multifunctional bioelectronics aims to combine several functions, such as drug delivery, diagnostics, and therapeutic interventions, into a single device, enhancing their biomedical applications. For instance, silk-based transient bioelectronics, powered by triboelectric nanogenerators (TENGs) enable real-time in vivo monitoring and therapeutic treatments. These systems are self-powered and biodegradable, with adjustable lifespans and sensitivity through silk molecular customization. 3 These multifunctional devices have the potential to revolutionize personalized medicine by providing more comprehensive health solutions.

Challenges 

Integrating bioelectronics into healthcare presents significant inherent regulatory and ethical challenges. As bioelectronic devices are advancing, especially those used in the medical industry like pacemakers and neural implants, the impact on users' health means that regulatory and ethical considerations are increasing in importance.

Ensuring the safety and efficacy of these devices requires rigorous testing and compliance with regulatory standards. Ethical considerations also arise regarding user privacy, data security, and informed consent, especially when sensitive health information is collected and shared. Addressing these challenges is crucial to building public trust and ensuring the responsible use of bioelectronics.

Moreover, although on-body bioelectronics are beneficial, there are also challenges in developing on-body bioelectronics, particularly regarding power supply, and user comfort. These challenges require innovative solutions, and some solutions, like flexible batteries, have already made significant differences in tackling some of these challenges.

Biocompatibility is another key challenge in developing in-body bioelectronics as these devices are placed inside the body; they must be made from compatible materials that do not provoke immune responses and can operate without causing harm to surrounding tissues. Moreover, maintaining the device's functionality over time, despite the harsh environment within the body, which includes exposure to fluids, enzymes, and mechanical stresses, is also a significant challenge.

Opportunities and Emerging Trends: The Future of Bioelectronics

Currently, one of the most compelling emerging trends in bioelectronics is the development of smart bioinks. These bioinks have enhanced functionalities, such as responding to environmental changes like temperature, pH, and chemical stimuli. For instance, smart bioinks can be designed to release therapeutic agents in response to specific stimuli, promoting targeted healing and enhancing treatment efficacy. 4 This adaptability of smart bioinks can lead to future bioelectronic devices that dynamically adjust to the body's needs, further improving their therapeutic potential.

Voltera's Role in Advancing Bioelectronics and Biocompatible Inks

Voltera is a leading provider of advanced materials dispensing solutions for printing bioelectronics prototypes. Voltera's NOVA supports a wide range of materials, allowing researchers to test and experiment with various substrates and conductive inks. This flexibility allows innovation in bioelectronics, offering opportunities for breakthroughs in multifunctional bioelectronics devices. For instance, NOVA enables researchers to print biocompatible inks, such as gold and silver-silver chloride with exceptional precision to facilitate prototyping complex bioelectronics. This advanced system supports the development of traditional rigid electronics, as well as flexible hybrid electronics (flexible, stretchable, and conformable). 

In particular, with a minimum line width of 100 µm and temperature-controlled dispensing, NOVA enables users to dispense biocompatible inks, pastes, gels, and adhesives on stretchable, soft, and flexible substrates, unlocking the ability to print bioelectronics that conform to the body’s natural contours.

Supporting Research and Innovation

Researchers worldwide are using Voltera's tools to push the boundaries of bioelectronics. For example, in a 2024 study, researchers utilized the Voltera’s NOVA PCB printer to fabricate organic electrochemical transistors (OECTs) as part of their investigation into electrochemical organic neuromorphic devices (ENODes). NOVA was employed to directly print transistors with specific PEDOT formulations onto glass substrates, enabling the precise patterning of silver feedlines and contact pads. The team achieved a compact design with a high degree of control over the devices' channel and gate structures, facilitating the integration of biocompatible gel-electrolytes. This method allowed the study to examine ENODe performance under varied electrolyte conditions, specifically focusing on short- and long-term plasticity for potential applications in brain-chip interfacing.5

Similarly, in another 2022 study, researchers utilized Voltera's NOVA to fabricate silver-based tattoo electrodes to monitor bioelectric signals. NOVA enabled precise extrusion printing of high-viscosity silver flake ink on porous tattoo paper, leading to electrodes with lower sheet resistance and better electrical performance compared to inkjet-printed alternatives. This improved efficiency by minimizing ink absorption into the substrate, and reducing impedance in bioelectrical measurements. 6

These researches, along with many others, are a testament to Voltera's commitment to supporting the next generation of bioelectronic innovations. Voltera's products, like NOVA and V-One, ensure that the next generation of devices continues to improve the quality of life for patients worldwide.

Conclusion

The importance of bioelectronics is self-evident, as these technologies have immense significance in advancing modern personalized medicine, real-time health monitoring, and patient outcomes, which ultimately have the potential to revolutionize the future of medicine. DIW technology is integral to these advancement as it enables precise prototyping of bioelectronic devices with biocompatible inks in both on-body and in-body applications. 

The projected market growth of bioelectronics is up to $33.6 billion by 2029, which indicates that this field is rapidly advancing and holds immense potential to reshape the future of healthcare.

Explore the future of bioelectronics applications 

For researchers and engineers looking to explore the next frontier of bioelectronics, Voltera's platforms provide the tools and support necessary to advance the field. Book a call with Voltera to learn how their technology can contribute to your bioelectronics applications.

References

1. Stavrinidou, E., & Proctor, C. M. (Eds.). (2022). Introduction to Bioelectronics: Materials, Devices, and Applications. AIP Publishing LLC. https://doi.org/10.1063/9780735424470_001

2. Electroceuticals/Bioelectric Medicine Market worth $33.6 billion by 2029. [Online] Markets and Markets. Available at: https://www.marketsandmarkets.com/PressReleases/electroceutical.asp (Accessed on September 4, 2024)

3. Zhang, Y., Zhou, Z., Fan, Z., Zhang, S., Zheng, F., Liu, K., ... & Tao, T. H. (2018). Self‐powered multifunctional transient bioelectronics. Small. https://doi.org/10.1002/smll.201802050

4. Maan, Z., Masri, N. Z., & Willerth, S. M. (2022). Smart bioinks for the printing of human tissue models. Biomolecules. https://doi.org/10.3390/biom12010141

5. Rana, D., Kim, C. H., Wang, M., Cicoira, F., & Santoro, F. (2024). Tissue-like interfacing of planar electrochemical organic neuromorphic devices. Neuromorphic Computing and Engineering. https://iopscience.iop.org/article/10.1088/2634-4386/ad63c6/meta

6. El-Hajj, Y., Ghalamboran, M., & Grau, G. (2022, July). Inkjet and extrusion printed silver biomedical tattoo electrodes. In 2022 IEEE International Conference on Flexible and Printable Sensors and Systems (FLEPS) IEEE. https://doi.org/10.1109/FLEPS53764.2022.9781535

7. Voltera [Online] Wevolver, Available at: https://www.wevolver.com/profile/voltera (Accessed on September 4, 2024)

8. NOVA. The future of printed electronics [Online] Voltera, Available at: https://www.voltera.io/nova (Accessed on September 4, 2024)

9. V-One. PCB prototyping made easy [Online] Voltera, Available at: https://www.voltera.io/v-one (Accessed on September 4, 2024)