Nishtha Chopra

Terahertz Communications in Human Tissues at the Nanoscale for Healthcare Applications

This letter investigates nanoscale wireless communications in human tissues. Starting from propagation models, validated through real experiments, channel capacity and transmission ranges are derived for different physical transmission settings. Results highlight the challenges characterizing the communication in such a medium, thus, paving the way to novel research activities devoted to the design of pioneering nanomedical applications.

Terahertz Channel Characterization Inside the Human Skin for Nano-Scale Body-Centric Networks

This paper focuses on the development of a novel radio channel model inside the human skin at the terahertz range, which will enable the interaction among potential nano-machines operating in the inter cellular areas of the human skin. Thorough studies are performed on the attenuation of electromagnetic waves inside the human skin, while taking into account the frequency of operation, distance between the nano-machines and number of sweat ducts. A novel channel model is presented for communication of nano-machines inside the human skin and its validation is performed by varying the aforementioned parameters with a reasonable accuracy. The statistics of error prediction between simulated and modeled data are: mean (μ)= 0.6 dB and standard deviation (σ)= 0.4 dB, which indicates the high accuracy of the prediction model as compared with measurement data from simulation. In addition, the results of proposed channel model are compared with terhaertz time-domain spectroscopy based measurement of skin sample and the statistics of error prediction in this case are: μ = 2.10 dB and σ = 6.23 dB, which also validates the accuracy of proposed model. Results in this paper highlight the issues and related challenges while characterizing the communication in such a medium, thus paving the way towards novel research activities devoted to the design and the optimization of advanced applications in the healthcare domain.

Nano-Communication for Biomedical Applications: A Review on the State-of-the-Art From Physical Layers to Novel Networking Concepts

Nano-communication-based devices have the potential to play a vital role in future healthcare technologies by improving the quality of human life. Its application in medical diagnostics and treatment has a great potential, because of its ability to access small and delicate body sites noninvasively, where conventional medical devices fall short. In this paper, the state of the art in this field is presented to provide a comprehensive understanding of current models, considering various communication paradigms, antenna design issues, radio channel models based on numerical and experimental analysis and network, and system models for such networks. Finally, open research areas are identified for the future directions within the field.

THz Time-Domain Spectroscopy of Human Skin Tissue for In-Body Nanonetworks

This paper presents experimental study of real human skin material parameter extraction based on terahertz (THz) time-domain spectroscopy in the band 0.1-2.5 THz. Results in this paper show that electromagnetic properties of the human skin distinctively affect the path loss and noise temperature parameters of the communication link, which are vital for channel modeling of in-body nanonetworks. Refractive index and absorption coefficient values are evaluated for dermis layer of the human skin. Repeatability and consistency of the data are accounted for in the experimental investigation and the morphology of the skin tissue is verified using a standard optical microscope. Finally, the results of this paper are compared with the available work in the literature, which shows the effects of dehydration on the path loss and noise temperature. The measured parameters, i.e., the refractive index and absorption coefficient are 2.1 and 18.45 cm-1, respectively, at 1 THz for a real human skin, which are vital for developing and optimizing future in-body nanonetworks.

Understanding and characterizing nanonetworks for healthcare monitoring applications

Terahertz (THz) region of the electromagnetic spectrum has been of wide interest during the past few years. It has been regarded as the promising working band for Nanoscale Communication. In this paper, experimental investigations and analysis using THz-TDS (THz Time Domain Spectroscopy) system are presented and discussed. The study is focused on biological modeling of artificial skin and thereby extracting the refractive index values at the THz band. The paper also compares the results with already reported papers. The results are promising and in agreement with minor variation due to different growth process and experimental environment.

Fibroblasts cell number density based human skin characterization at THz for in-body nanonetworks

This paper presents the investigation of the electromagnetic properties of human skin tissues using Terahertz Time Domain Spectroscopy (THz-TDS). The material parameters i.e., refractive index and absorption coefficient are extracted for artificially synthesized skin cultured using fibroblast cells and collagen type I reagent. The increase in cell count number by 200% causes a distinctive decrease in refractive index and absorption coefficient values. In addition to material parameters, in-body channel parameters i.e., total pathloss and molecular noise temperature of the skin are also calculated. The results show the dependency of channel parameters on molecular features and hydration level of the skin. Such findings will pave the way for more rigorous THz channel analysis and network modeling to be applied for body-centric nano-communication specifically in the bioengineering domain.

Effects of non-flat interfaces in human skin tissues on the in-vivo Tera-Hertz communication channel

Abstract The influence of the interface type between the epidermis and dermis layers within the human skin tissue is investigated in this paper by introducing two models with different interfaces ( i.e. , 3-D sine and 3-D sinc function). By comparing the power loss of both models, it is evident that the common flat model is sufficient in case of electromagnetic communication links studies within the human tissue without the need of complicated detailed models. There is no significant difference between the power loss results of the flat model to the mean value of the power loss of the stratified model with sinc interface while the difference between the flat one from the stratified model with sine interface is less than 5 dB. However, the influence of the roughness can be presented by the deviation. From the numerical analysis, it is shown that for sine model it reaches almost 10 dB at a distance of 600 μ m , when the span changes. Meanwhile, the impact of the antenna location is demonstrated by placing the antennas (dipoles) in two different locations, which shows limited effects (the difference is less than 3 dB). Finally, the impact of the sweat duct is studied, showing its close relationship with the state of the sweat duct that the sweat-filled sweat duct working as PEC would reduce the power loss by almost 5 dB compared with the normal sweat duct without sweat.

Investigating Electromagnetic Material Properties of Collagen at THz for Health Monitoring Applications

The elegant concept of Nanocommunication at terahertz (THz) frequency is proposed with its main focus on investigating electromagnetic material properties of synthesized Dermis layer of the skin via THz-Time Domain Spectroscopy (TDS). The paper highlights the study of human skin and cell culture. Methods are applied to synthesize collagen and measurements are carried out in the THz band ranging from 0.1-3THz. The results are further proposed for Nanonetwork channel propagation models and transmission schemes based on THz electromagnetic communication.

Physical Layer Authentication in Nano Networks at Terahertz Frequencies for Biomedical Applications

This paper presents a study on physical layer authentication problem for in vivo nano networks at terahertz (THz) frequencies. A system model based on envisioned nano network for in vivo body-centric nano communication is considered and distance-dependent pathloss based authentication is performed. Experimental data collected from THz time-domain spectroscopy setup shows that pathloss can indeed be used as a device fingerprint. Furthermore, simulation results clearly show that given a maximum tolerable false alarm rate, detection rate up to any desired level can be achieved within the feasible region of the proposed method. It is anticipated that this paper will pave a new paradigm for secured, authenticated nano network for future applications, e.g., drug delivery and Internet of nano-things-based intelligent office.

Collagen Analysis at Terahertz Band Using Double-Debye Parameter Extraction and Particle Swarm Optimisation

This paper focuses on the analysis of cultivated collagen samples at the terahertz (THz) band using double debye model parameter extraction. Based on measured electrical and optical parameters, we propose a model to describe such parameters extracted with a global optimisation method, namely, particle swarm optimisation. Comparing the measured data with ones in the open literature, it is evident that using only cultivated collagen is not sufficient to represent the performance of the epidermis layer of the skin tissue at the THz band of interest. The results show that the differences between the measured data and published ones are as high as 14 and 6 for the real and imaginary values of the dielectric constant, respectively. Our proposed double debye model agrees well with the measured data.