By Kalwinder KaurJan 28 2013
Image Credits: Billion Photos/Shutterstock.com
Embedded sensor networks are being extensively used to monitor the human body, or more specifically, to monitor the parasympathetic and sympathetic functions of the autonomic nervous system.
Many tiny wireless sensors are arranged on a patient’s body creating a wireless body area network or a WBAN. These networks are capable of monitoring vital signs, as well as offering real-time feedback. The obtained data is essential for enabling several diagnostic procedures by continuously monitoring chronic conditions or how a patient has recovered from an illness.
A WBAN normally consists of lightweight, minute, low-power sensing devices, wireless transceivers and management electronics. These are implantable and wearable sensor nodes that sense biological information from the human body and wirelessly transmit it over a short distance. On the other side of the wireless connection, a control device, either worn on the body or placed in an accessible location, receives the data. The sensors are designed in a manner that allows them to detect medically relevant signals and symptoms such as photoplethysmograms, electrocardiograms, electroencephalography, pulse rate, pressure, and temperature.
For the first time, cyborg tissue has been created by Harvard scientists by integrating a 3D network of biocompatible, functional nanoscale wires into engineered human tissue.
Lieber C.M, et al (2012) designed a system for creating nanoscale scaffolds that can be seeded along with cells and develop into tissue. The use of electrodes for measuring activity in cells or tissues has been already utilized in the past, however, electrodes have been proved to cause damage to these cells or tissues. In contrast, the new nanoscale technology will enable working on the same scale as the unit of the biological system without any interruption to the normal tissue function. This innovative technology is a great attempt to merge biology and electronics.
According to one of the researchers, Kohane D.S, the autonomic nervous system monitors chemistry, pH, oxygen and other factors and stimulates responses whenever required. To ensure fine control at tissue and cellular level, it is important to simulate the intrinsic feedback loops of the body.
Inspired by the autonomic nervous system and its functioning, the research team fabricated mesh-like networks of nanoscale silicon wires. An organic polymer mesh, arranged on a 2D substrate, surrounds the nanoscale wires and acts as the critical sensing element.
In this study, nanoscale electrodes connecting the nanowire elements were incorporated in the mesh to help nanowire transistors determine cell activity without causing any damage. After completion, the networks became porous, enabling them to be seeded with cells and grow in three-dimensional cultures. The team was successful in engineering tissues using heart and nerve cells without impacting the activity or viability of the cell. The detection of electrical signals deep within the tissue was possible with the use of these devices. Furthermore, the changes in the signals were determined in response to neurostimulating or cardio drugs. The team also engineered blood vessels and determined pH changes both outside and inside the vessels.
Brown L et al. from the Holst Centre of the Netherlands conducted a study in 2009 engineering a body area network (BAN) for monitoring the responses of the autonomic nervous system. The BAN was based on a low power, generic, small, wireless sensor node. Exclusively designed for the purpose of an ultra-low power sensor, front-ends were used to monitor the physiological signals connected to Uninodes. The BAN comprised of two UniNodes: one placed on a chest belt for the recording of respiration and ECG, and second, a wrist sensor to determine skin conductance.
One example of research that aims to characterize body area networks includes work by Professor Kaveh Pahlavan, Director of the Center for Wireless Information Network Studies (CWINS). His goal, to date, is to merge wireless networking functionality into body area networks. The result will potentially be important for medical applications, including the monitoring of robotic technology that is becoming increasingly popular among the medical industry in assisting inpatient care:
Characterizing Body Area Networks
The technology of using sensors to monitor functions of the autonomic nervous system has several potential applications. One example is the pharmaceutical industry where it could be used to accurately study how newly developed drugs behave in 3D tissues rather than in thin cultured cell layers.
It is anticipated that soon this technology will help monitor changes in the body and respond accordingly, either through the release of a drug or through electrical stimulation.
A large number of researchers are involved in a project termed as Guardian Angels for a Smarter Life, which is a good way to describe the future of electronic sensor networks. These minute devices are being designed using nanomechanisms and will help all citizens, from infants to the elderly. The same device can be personalized and embedded in fabrics.
The guardian angel sensors will be able to detect environmental stimuli and physical and emotional reactions in the human body. The devices will also act as ECG readers, monitor oxygen levels in the blood, heart rate and blood sugar levels. Biological data like this will be essential to prevent illnesses such as diabetes, heart disorders and strokes. Nanosensors can also function as gyroscopes and accelerators, being capable of identifying anxiety, stress, and attention through sensors measuring brain waves, galvanic skin response, heart rate, and possibly, hormonal activity.
Sources and Further Reading
- Ming-Zher Poh. A Wearable Sensor for Unobtrusive, Long-Term Assessment of Electrodermal Activity. IEEE Transactions on Biomedical Engineering. 2010; 57 (5):1243-1252.
- Brown L, et al. Body area network for monitoring autonomic nervous system responses. This paper appears in: Pervasive Computing Technologies for Healthcare, 2009. PervasiveHealth 2009. 3rd International Conference on. 2009; pages 1-3.
- Guardian Angels for a smarter life
- Bozhi Tian, Jia Liu, Tal Dvir, Lihua Jin, Jonathan H. Tsui, Quan Qing, Zhigang Suo, Robert Langer, Daniel S. Kohane, Charles M. Lieber. Macroporous nanowire nanoelectronic scaffolds for synthetic tissues. Nature Material. 2012;11:986–994.
This article was updated on 13th February, 2020.
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