Sensor Technology in Neuroscience

Dr. Sub Reddy (C.Chem. MRSC) obtained his first class degree in Chemistry from the University of Manchester. He received his Ph.D. in Membrane-based Electrochemical Biosensing from the same University (1996). His post-doctoral research interests have included the development of quartz crystal-based biosensors, operating in the liquid phase (University of Wales, Bangor; 1994-1997) and the development of application-specific odour sensors (UMIST, Manchester; 1997-1998).Dr. Reddy was Senior Lecturer in Applied Analytical Chemistry at the University of Surrey and recently moved to the University of Central Lancashire as Senior Lecturer in Analytical Chemistry. Current research interests include the development of smart, permselective and biocompatible molecular imprinted polymers and membrane materials for the sensor/sample interface and the advancement of smart materials-based electrochemical, quartz crystal and optical sensors for medical, food and environmental applications. He is particularly interested in developing hydrogel-based molecularly imprinted polymers (HydroMIPs) for the determination of protein markers and other biomarkers and construction of biosensors.

• Introduction;Surface Chemistry of Neurons on Substrates;Detection using Microelectronic Devices;Microelectrode Arrays and Light Addressable Potentiometric;Vibrational Fields - Acoustic Physics, Scanning Kelvin Nanoprobe;The Interface Between Brain and Artificial Implants;Future Perspectives

Despite modern scientists’ best efforts, neuroscience, an extremely complex field that tries to comprehend the functionality of a human brain, is still in its infancy. There is much that is yet not understood in the human brain partly due to the limitations of existing tools and sensors, which are used to accurately probe and image the human brain. Successful development of devices and technologies for neuroscience requires interdisciplinary expertise in biosensors, chemistry, surface science, engineering and molecular biology. Taking into consideration the possibility of the diverse background of its readers, this book provides a simplified yet thorough treatment of the necessary topics needed for a researcher to develop either in vivo or in vitro sensors for the human brain. The topics of each chapter have been carefully chosen such that the reader can both understand the basic operating principles of different sensing techniques as well as be updated with the current state-of-the-art technology used for neurosensors.The book is very well organized, starting with An introduction to biosensor technology in Chapter 1, which gives the readers insight on a sensor’s anatomy, the necessity of receptors on sensors and how they can be attached on the sensor’s active surface. Receptors or probes that have excellent binding on the transducer will produce a sensor with high sensitivity and selectivity. To provide the reader with an overview of available sensor technology, this chapter also describes the mechanisms of different biosensors namely: electrochemical, piezoelectric or acoustic waves and optical. For each mechanism, the measuring methods of the biosensor are explained in detail. As an example, for electrochemical sensors, the governing equations and methodology of using potentiometry, amperometry and impedance spectroscopy were summarized and illustrated well with schematics. This chapter gives the reader an idea of which type of sensor could be suitable for his or her application.Chapter 2: The Cell-Substrate Surface Interaction, explains about how the cells interact on the surface of solids. This chapter is intended for different audiences; the first part is for non-chemists, which describes the basics of surface chemistry and how it will affect the behavior of cells. The second section, intended for non-biologists, introduces the reader to eukaryotic cells, their surrounding environment and the extracellular matrix. As the book is regarding development of sensors for neuroscience, a brief background on neurons, their anatomy, types, action potential and electrical conduction is described next. To study the behavior of neurons, it is often necessary to grow and culture them on the sensor. The final sections of this chapter illustrate the important factors to achieve cellular adhesion, growth and proliferation on different sensor substrates. Chapter 3: Electronic Detection Techniques, illustrates the electrogenic characteristics of the neuron which makes it possible for scientists to study the chemical reactions in the cell due to applied electrical excitation and vice versa. This chapter also describes the charge transfer that occurs at the neuro-electronic surface, which can be measured as subthreshold currents via microelectrode arrays and field effect transistors. Microelectrode arrays are often used for in vitro experiments and can be coupled with microfluidic lab on chips to create specific environmental conditions for the neurons. The miniature size of the sensors and array implementation allow rapid and parallel measurements, which have been used for toxicology tests and drug discovery. Chapter 4: Nanosensing the Brain illustrates the latest advancement in the field of neurosensors, where nanoparticles, nanotubes and nanowires are used to improve the sensitivity and accuracy of the microelectrode arrays and transistors described in Chapter 3.Chapter 5: The Vibrational Field and Detection of Neuron Behavior builds on the electrochemical, acoustic and optical sensing principles explained briefly in Chapter 1. Classical microscopy methods are plagued by detection limits and only provide information on the physical aspects of cells. Thus, the focus of this chapter is on the usage of label-free techniques that measure the frequencies and amplitudes of transducing signals in cells to detect molecular behavior and cellular events. Unlike the earlier chapters, which explain mainly about measuring tools and methods, Chapter 6: The Biomimetic Interface between Brain and Electrodes: Examples in the Design of Neural Prostheses, describes novel brain prosthetics which could be used to heal both the human brain and the functionality of disabled human bodies. This chapter is most interesting since it explores the wide range of possibilities that neural prostheses could be used, namely i) As electrodes in deep brain simulation to treat debilitating brain disorders such as Parkinson’s and epilepsy, ii) As motor cortex prostheses, which are brain-controlled robotic limbs that increase the mobility of paraplegics and amputees, iii) As retinal prosthetic interfaces to improve loss of vision due to the degeneration of the retina.The author concludes the book with Chapter 7: A Look at the Future, which provides prospective of future research in neuroscience. Promising research fields include quantum neurobiology, nanoneuromedicine, neuropharmacology, regenerative techniques, stem cells and many more. Overall, the book has been a very interesting read. The author has managed to explain and demystify the complex topic of neuroscience research using very clear and simple language. The best part about the book is that it does not require specific background knowledge of the topic, making it easy for readers of different disciplines to understand the operating principles and key design criteria for a neuro sensor. I would highly recommend the book for scientists that wish to start their research in the field of neuroscience, or for experienced neuroscientists that wish to explore alternative mechanisms for their sensors.