Molecular Communication Receiver Research Articles

Fabrication and microfluidic analysis of graphene-based molecular communication receiver for Internet of Nano Things (IoNT)

Bio-inspired molecular communications (MC), where molecules are used to transfer information, is the most promising technique to realise the Internet of Nano Things (IoNT), thanks to its inherent biocompatibility, energy-efficiency, and reliability in physiologically-relevant environments. Despite a substantial body of theoretical work concerning MC, the lack of practical micro/nanoscale MC devices and MC testbeds has led researchers to make overly simplifying assumptions about the implications of the channel conditions and the physical architectures of the practical transceivers in developing theoretical models and devising communication methods for MC. On the other hand, MC imposes unique challenges resulting from the highly complex, nonlinear, time-varying channel properties that cannot be always tackled by conventional information and communication tools and technologies (ICT). As a result, the reliability of the existing MC methods, which are mostly adopted from electromagnetic communications and not validated with practical testbeds, is highly questionable. As the first step to remove this discrepancy, in this study, we report on the fabrication of a nanoscale MC receiver based on graphene field-effect transistor biosensors. We perform its ICT characterisation in a custom-designed microfluidic MC system with the information encoded into the concentration of single-stranded DNA molecules. This experimental platform is the first practical implementation of a micro/nanoscale MC system with nanoscale MC receivers, and can serve as a testbed for developing realistic MC methods and IoNT applications.

A Stochastic Model for Characterizing Fluctuations in Chemical Sensing

The chemical sensing process can be understood as the physical process consisting of binding and unbinding reactions on the sensing surface. The random nature of the reactions lead to fluctuations in the response of a sensor. The response of the sensor is modeled in the form of a stochastic differential equation (SDE). The model is developed by formulating the binding and unbinding reactions in the form of Bernoulli trials. The transition probability density function (pdf) of the number of binded analyte molecules X <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> , at a given time instant t, has been evaluated using the Bernoulli trial representation. The obtained pdf is used to derive the Fokker Planck equation (FPE) for the stochastic process. The FPE has a direct correspondence with the desired SDE model. A maximum aposteriori (MAP) estimation method has been proposed for evaluating the parameters. The SDE model for the fluctuations in the sensor signal has been evaluated. The frequency spectrum of the fluctuations is evaluated using the SDE. The proposed model is used to analyze noise due to the ligand-receptor kinetics in the receiver in molecular communication. The utility of the model in agent identification applications has been demonstrated.

Concentration-based demodulation scheme for mobile receiver in molecular communication

Molecular communication is a novel approach for conveying information at the nano- or micro-scale. The modulation and demodulation schemes for fixed transmitter and receiver nanomachine have been studied in previous literature. However, it is still a big challenge to perform the demodulation when the transmitter and/or the receiver is mobile. In this paper, a simple and effective demodulation scheme for a mobile receiver is investigated for 3-D scenario with drift. Inter-symbol interference (ISI) mitigation, bit alignment scheme and an adaptive threshold mechanism are proposed for correct demodulation. The parameters such as symbol interval and flow/receiver velocity ratio are simulated and analyzed in terms of bit error rate.