Two metallic microelectrodes were printed on a flexible polyester film and integrated into a microfluidic channel. by applying a minute sinusoidal voltage at a specific rate of recurrence, while monitoring the produced current response. The current-voltage percentage with this electrochemical impedance spectroscopy (EIS) provides the impedance signal and allows the precise monitoring of changes in conductivity/resistivity or charging capacity of an electrochemical reaction or interface where bio-chemical relationships happen. A micro-device was fabricated Dopamine hydrochloride to record impedance Dopamine hydrochloride changes for analysis of HIV viral nano-lysates . In this study, multiple HIV-1 subtypes Comp were captured using magnetic beads-coated with anti-gp120 antibodies, followed by viral lysis. The nano-lysate samples were then applied to microdevices consisting of a pyrex wafer with two gold microelectrodes. EIS was then recorded from 100 Hz to 1 1 MHz to evaluate impedance changes between multiple HIV-1 subtypes and control (sample without HIV-1). This device shown that HIV-1 samples produced unique impedance values compared to settings. HIV-1 samples mixed with Epstein-Barr Computer virus (EBV) were also tested and the results were not significantly different from that of HIV-1, demonstrating the specificity of HIV detection. To demonstrate portability of this device, the same strategy was applied to polyester-based flexible materials (Fig. 1A) . Two metallic microelectrodes were imprinted on a flexible polyester film and integrated into a microfluidic channel. Nano-lysate of HIV-1 samples from plasma and whole blood samples were then applied into the microchannels and the impedance was recorded from 100 Hz to 1 1 MHz. This flexible impedance biosensor showed its potential as an inexpensive (less than $2 in material cost) and disposable assay to selectively capture and detect HIV-1 from a medical specimen. In another study, mass-producible and flexible impedance detectors were fabricated using conductive inks . Multiple HIV-1 subtypes, EBV, and Kaposis Sarcoma-associated Herpes Virus (KSHV) were recognized from a fingerprick volume (50 L) of physiological buffer, plasma, and artificial saliva samples. Further developments in reducing the number of sample processing methods will significantly improve these detectors for POC applications. Open in a separate windows Fig. 1 Electrochemical Assays for HIV-1 Detection(A) Two-rail microelectrodes were printed on a flexible polyester-based material for detection of HIV nano-lysate. HIV was captured with magnetic particles coated with anti-gp120 antibodies (off-chip), adopted transmission measurements by electrochemical impedance spectroscopy . (B) A platinum nanocluster altered graphene electrode (GR/AuNCs) was fabricated to detect HIV target sequences using an exonuclease III (Exo III)-aided target recycling amplification method . In this method, the electrode surfaces were altered with capture probes (aptamers) and labeled with methylene blue (MB). During hybridization between target and capture probes, nucleic acids folded themselves into a duplex DNA structure, followed by the digestion of the capture probe by Exo III from its 3-end, resulting in the release of MB molecules, which were recorded by differential pulse voltammetry technique (A) was adapted with permission from . (B) was adapted with permission from . Copyright (2015) American Chemical Society. 2.1.2. Graphene-based detectors and assays Graphene material consists of a two-dimensional (2D), single-layer sheet of sp2-hybridized carbon atoms, which form a hexagonal lattice structure [28C30]. From a structural and practical perspective, graphene is definitely a semiconductor material and behaves like a semimetal due to its zero-bandgap [30C32]. This material has a amazing ambipolar electric-field effect and exhibits a large theoretical surface area (2630 m2/g) with superior electrical conductance (64 mS/cm) [33,34]. In addition, graphene has a low charge-transfer resistance and a rapid electron transfer rate [30,35,36]. Due to these encouraging physical and electrochemical features, graphene has been broadly used as an electrode material for electrochemical sensing modalities, and been applied into a few medical biosensing and diagnostic applications [17,37C39]. Like a potential diagnostic tool, graphene-based materials have been altered with nucleic acids, aptamers, peptides, and Dopamine hydrochloride antibodies to measure current and amperometric changes within biochemical reaction such as redox relationships. For instance, a platinum nanocluster altered Dopamine hydrochloride graphene electrode (GR/AuNCs) was developed to measure HIV-originated target sequences using an exonuclease III (Exo III)-aided target recycling amplification strategy (Fig. 1B) ..