Next-Generation Medical Devices for Brain-Computer Interfaces

By- Paul Golata, Mouser Electronics

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The cursor flashes at me, taunting me to put down something. I have nothing, so I amuse myself by clocking the refresh rate for a minute to ascertain its value. I find it is blinking at a rate of 50Hz. Each flash is telling me I have nothing so far. It feels as if a Neuralizer from the movie Men in Black (1997) erased my thoughts. It is the age-old battle for most writers: How to start a good story, how to write an article to engage and inform. How am I to get the thoughts and ideas in my brain onto the page? It is a battle of transferring what I wish to express into the published word.

If only I had a Brain-Computer Interface (BCI) to intelligently augment my brain with endless amounts of valuable data, stirring an instant stream of consciousness from my keyboard onto the computer screen.

Well, you are not here to learn about my writing problems. We’re here to discuss BCIs.

What is BCI?

BCI applications are rapidly transforming the medical device industry and will continue to do so because of their benefits. BCI applications refer to devices that allow users to interact with computers, measuring the user’s brain activity. The electrical activity is most commonly measured with an electroencephalogram (EEG), recognizing the energy and frequency patterns of the brain. Artificial intelligence (AI) and machine learning (ML) enable greater accuracy and reliability in evaluating and developing BCI applications. In the following, we will examine this field and some of the critical electronic components within the signal chain required to measure brain waves and other bodily functions and how AI puts it all together.

BCI & EEG

The human brain produces oscillating electronic voltages. The typical value of these voltages is minimal, measured in units on the order of millionths of volts. The most common way to collect and analyze these brain-wave voltages is through an electroencephalogram (EEG). An EEG is an electrophysiological monitoring method to record electrical activity on the scalp. It captures signals directly related to the brain waves happening directly under the skull.

Figure 1: A woman undergoing non-invasive electroencephalography (EEG). (Yakobchuk Viacheslav/Shutterstock.com)

BCI via an EEG can be unidirectional (one-way) or bidirectional (two-way). Bidirectional allows information to flow both ways, thus opening the brain to feedback and future adjustments. EEGs can be invasive, semi-invasive, or non-invasive. Invasive EEGs involve directly locating and connecting devices into the human brain. Semi-invasive EEGs can be placed between the brain and the skull. Non-invasive is generally done by a cap placed on the skull with various electrodes. EEGs provide temporal resolution of @0.05 seconds and spatial resolutions on the order of 10mm. Other techniques, besides the electrical technique employed by EEGs, can be used to gather data. These techniques can employ magnetic, metabolic, or other forms.

Brain waves are classified into one of five general categories based on their frequency (Table 1). Medical researchers break these into bands because each band represents a distinct way a brain operates in performing its functions. For example, critical activities such as memory and recollection happen especially, but not exclusively, in the theta band. Researchers use these bands to analyze what might be going on if it appears signals are too little, too great, or an optimal amount.

Table 1: The five general categories of brain wave bands. Each frequency range is a nominal value and not necessarily absolute. (Source: Author)

An EEG acquires the brainwave signals and digitizes them. They are then signal-processed where features can be extracted and translation algorithms perform classifications. They also can be printed out or recorded for future analysis. Signal outputs can be utilized to form device commands to provide instructions related to motor control, locomotion/movement, and environmental conditions or stimuli. BCI helps allow disabled people to have more control of their external environments.

BCI and the Human Condition

Because of human biology, our senses and our intelligence have fundamental limitations. It is conceivable that brain-computer interfaces and implants could enhance or provide new sensory information and augment biological capabilities. A primary consideration in merging man and machine is understanding how the machine and the human interact and exchange information between themselves on a real-time basis, since they operate in two different domains. More work remains to be done to understand how the mutual coordination of individually-addressable neurons directing the brain can function in its environment while maintaining coordination with the digitally-addressable domain of the interface.

BCI Research

BCI is also being investigated to look at areas to help humanity, including restoring or enhancing human vision, motor recovery for disabled limbs, and brain mapping to assist restoring and correcting various neurological damage and disorders. Brain mapping can lead to a greater understanding of seeing how human thought is realized into human action. It can lead to augmented human learning, new or enhanced human sensing, and new embedded autonomous neural systems. Let’s look at two examples of where BCI can continue to evolve and lead.

Superhuman Cognition

Billionaire Elon Musk is actively investigating BCI issues. He is one of the founders of Neuralink Corp., a neurotechnology company developing implantable brain-machine interfaces. Neuralink is working on building better tools for communicating with the brain. These founders believe that, with the right team, the applications for this technology are limitless. Neuralink is exploring the possibility of embedding into the brain ultrafine electronic threads that permit neural activity.

One of Musk’s stated goals is to achieve “superhuman cognition.” Inventor and futurist Ray Kurzweil believes that human intelligence is characterized by its remarkable ability to recognize patterns. He views human intelligence as an evolutionary, self-organizing hierarchical system operating in the context of a biological pattern-recognition machine. Musk is motivated to achieve superhuman cognition based upon his desire for humanity to negotiate more proficiently in understanding the emergence and spread of more powerful AI, which is becoming ever more adept in its excellence at pattern recognitions.

New Senses

When looking at how BCI can enhance human senses, one can consider the case of Neil Harbisson, cofounder of the Cyber Foundation. He has been recognized as the world’s first cyborg. Born color-blind, Harbisson has permanently installed an antenna into his skull so that he can now literally hear color, substituting his auditory sense in place of his visual limitation. Harbisson is actively advocating a future in which humans incorporate technology into their bodies.

Sensor Hubs

Supporting these efforts, sensor hubs are being employed in various ways to collect additional biometric information beyond BCI. Sensor hubs use multiple sensors and a microcontroller to collect and analyze numerous human parameters not directly accessed by brain waves. These can include collecting information about the human pulse heart rate, pulse blood oxygen saturation (SpO2), and estimated blood pressure.

Ensuring High-Quality Data

Because brain signals are so small, the entire electronic signal chain is prioritized in its design to minimize noisy, spurious, or artifact signals. The patient might induce these sources through their physical movements, sweating, eye movements, heart rhythms, and the like. Electrical errors can result from 50Hz/60Hz noise, electrode-skin contact issues, and cable movements.

Successful electronic component selection will focus on utilizing high-precision, low-noise, high-resolution signal chain products. Low-noise amplifiers (LNA), unity-gain buffers, and precision analog-to-digital converters (ADCs) are chosen to prevent the introduction of unwanted signals into the chain while providing the ability to resolve data accurately and reliably correctly. Differential amplifiers and bandpass filters are also employed to ensure only high-quality data is transmitted. Appropriate connectors and jumpers are needed to get accurate signals into and out of the brain. Let’s look at how Molex provides these solutions.

Connecting into the Brain

Molex 0.25mm-Pitch Premo-Flex Jumpers offer reliable connectivity in a compact design for tight packaging applications (Figure 2). The jumpers deliver durable, ultra-flexible, cost-effective solutions for printed circuit board (PCB) connections in virtually any industry. These FFC/FPC jumpers are available in standard lengths, pitches, and circuit sizes to accommodate a wide range of flexible interconnect requirements between two PCBs. Molex 0.25mm-Pitch Premo-Flex Jumpers are ideal for medical applications, including patient monitoring for signals, including the body’s condition, surgical equipment, and telehealth.

Molex 0.25mm Pitch Easy-On FPC Connectors offer a 50V voltage rating, 50MΩ insulation resistance, and 150VAC dielectric withstanding voltage (Figure 3). These connectors provide designers with a range of sizes and styles to accommodate other PCB components. Molex 0.25mm Pitch Easy-On FPC Connectors are ideal for next-generation medical devices.

Figure 3: Molex 0.25mm Pitch Easy-On FPC connectors offer a 50V voltage rating, 50MΩ insulation resistance, 150VAC dielectric withstanding voltage, and are ideal for next-generation medical devices. (Mouser Electronics)

AI with BCI

AI and its subsets, including machine learning and deep learning (DL), are enabling approaches in EEG-based BCIs (Figure 4). DL can offer automatic classifications of EEG signals. This effort allows for the data to be utilized in various applications and other convolutional neural networks (CNN) training. At present, human expertise supports AI approaches. The desire is to eliminate artifacts, increase the data quality, and continue to realize gains in AI technology so that measured brain wave signals can continue to exhibit exponential increases in their ability to be classified by AI through DL techniques.

Figure 4: Artificial intelligence, machine learning, and deep learning development over time. (Source: elenabsl/Shutterstock.com)

Conclusion

EEG-based BCI relies on high-performance electronic signal chains. Careful consideration of all critical electronic components, including reliable connectivity in compact designs, are needed to accurately measure EEG and other bodily functions. AI and DL techniques enable dynamic EEG data to receive better interpretations and allow humanity to realize more benefits from BCI. BCI will continue to be an emerging method for human-machine interfacing. And one day, it might offer a cure to any mental block we encounter, especially the empty page that any writer will eventually face.

Refer to the Improving Lives with Digital Healtcare Molex eBook for more information about BCI applications.

Author

Paul Golata joined Mouser Electronics in 2011. As a Senior Technical Content Specialist, Mr. Golata is accountable for contributing to the success in driving the strategic leadership, tactical execution, and overall product line and marketing direction for advanced technology-related products. He provides design engineers with the newest and latest information delivered through the creation of unique and valuable technical content that facilitates and enhances Mouser Electronics as the preferred distributor of choice. Prior to Mouser Electronics, he served in various manufacturing, marketing, and sales-related roles for Hughes Aircraft Company, Melles Griot, Piper Jaffray, Balzers Optics, JDSU, and Arrow Electronics. Paul holds a BSEET from DeVry Institute of Technology in Chicago, IL; an MBA from Pepperdine University in Malibu, CA; an MDiv with BL, and a PhD from Southwestern Baptist Theological Seminary in Fort Worth, TX . For questions, contact Mr. Golata at paul.golata@mouser.com.

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