Minimally Invasive Microneedle: A Novel Approach for Drug Delivery System and Infected Wound Care Management

Chronic wound healing has become an area of fundamental research. Wound healing for a diabetic patient is one of the significant challenges in the biomedical field. Diabetes is a globally challenging disease that has affected around 400 million people. Many therapeutic factors are introduced to treat chronic wounds, with minimal success due to difficulty in delivery of the drug to the wound location. Microneedle patches are considered an efficient medical treatment procedure to address wound healing problems. The wound healing is accelerated, and the bacterial infection is inhibited by the devices based on microneedle with the loaded active drugs (including hemostatic drugs, bacterial drugs, and anti-inflammatory drugs). The wound healing process is generally divided into three steps: inflammation, proliferation, and tissue remodeling. This chapter will discuss the significant challenges and the advantages of microneedle applications in chronic wound healing

Design guidelines for thin diaphragm-based microsystems through comprehensive numerical and analytical studies

This paper presents comprehensive guidelines for the design and analysis of a thin diaphragm that is used in a variety of microsystems, including microphones and pressure sensors. It highlights the empirical relations that can be utilized for the design of thin diaphragm-based microsystems (TDMS). Design guidelines developed through a Finite Element Analysis (FEA) limit the iterative efforts to fabricate TDMS. These design guidelines are validated analytically, with the assumption that the material properties are isotropic, and the deviation from anisotropic material is calculated. In the FEA simulations, a large deflection theory is taken into account to incorporate nonlinearity, such that a critical dimensional ratio of /ℎ or 2/ℎ can be decided to have the linear response of a thin diaphragm. The observed differences of 12% in the deflection and 13% in the induced stresses from the analytical calculations are attributed to the anisotropic material consideration in the FEA model. It suggests that, up to a critical ratio (/ℎ or 2/ℎ ), the thin diaphragm shows a linear relationship with a high sensitivity. The study also presents a few empirical relations to finalize the geometrical parameters of the thin diaphragm in terms of its edge length or radius and thickness. Utilizing the critical ratio calculated in the static FEA analysis, the basic conventional geometries are considered for harmonic analyses to understand the frequency response of the thin diaphragms, which is a primary sensing element for microphone applications and many more. This work provides a solution to microelectromechanical system (MEMS) developers for reducing cost and time while conceptualizing TDMS designs

Bio-synthesized silver nanoparticle modified glassy carbon electrode as electrochemical biosensor for prostate specific antigen detection

Prostate cancer is the second leading cause of death for men after lung cancer. Therefore, early detection of cancer proteins or biomarkers is crucial in assessing the disease's reappearance after treatment. Here, we have reported the glassy carbon electrode (GCE) based electrochemical biosensors fabricated using Carbon-Microelectromechanical Systems (C-MEMS) technology for prostate-specific antigen (PSA) quantification. This report also presents the biosensor improvement by modifying the GCE with silver nanoparticles (AgNPs). Moreover, our investigation extends to bio-synthesized AgNPs that bring together advantageous chemical and physical attributes at a reasonable cost. In addition, AgNPs modified GCE have a more comprehensive anodic potential range [˗0.2 V to +0.3 V] than bare glassy carbon (GC). Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) measurements were used to examine the electrochemical response of the biosensors. As a result of the use of AgNPs-modified GCE, we have developed a label-free analytical system for prostate cancer detection, which can provide a linear response in the concentration range of 1 pg/ml - 3 µg/ml in a reasonably simple operation. The developed biosensors may be used for the early detection of prostate cancer in clinical analysis due to the excellent sensitivity demonstrated by this electrochemical biosensor

Fabrication of 3D Carbon Microelectromechanical Systems (C-MEMS).

A wide range of carbon sources are available in nature, with a variety of micro-/nanostructure configurations. Here, a novel technique to fabricate long and hollow glassy carbon microfibers derived from human hairs is introduced. The long and hollow carbon structures were made by the pyrolysis of human hair at 900 °C in a N2 atmosphere. The morphology and chemical composition of natural and pyrolyzed human hairs were investigated using scanning electron microscopy (SEM) and electron-dispersive X-ray spectroscopy (EDX), respectively, to estimate the physical and chemical changes due to pyrolysis. Raman spectroscopy was used to confirm the glassy nature of the carbon microstructures. Pyrolyzed hair carbon was introduced to modify screen-printed carbon electrodes ; the modified electrodes were then applied to the electrochemical sensing of dopamine and ascorbic acid. Sensing performance of the modified sensors was improved as compared to the unmodified sensors. To obtain the desired carbon structure design, carbon micro-/nanoelectromechanical system (C-MEMS/C-NEMS) technology was developed. The most common C-MEMS/C-NEMS fabrication process consists of two steps: (i) the patterning of a carbon-rich base material, such as a photosensitive polymer, using photolithography; and (ii) carbonization through the pyrolysis of the patterned polymer in an oxygen-free environment. The C-MEMS/NEMS process has been widely used to develop microelectronic devices for various applications, including in micro-batteries, supercapacitors, glucose sensors, gas sensors, fuel cells, and triboelectric nanogenerators. Here, recent developments of a high-aspect ratio solid and hollow carbon microstructures with SU8 photoresists are discussed. The structural shrinkage during pyrolysis was investigated using confocal microscopy and SEM. Raman spectroscopy was used to confirm the crystallinity of the structure, and the atomic percentage of the elements present in the material before and after pyrolysis was measured using EDX

Green synthesized silver nanoparticles functionalized interdigitated electrodes for bacterial sensing using non-faradaic electrochemical impedance spectroscopy

In this study, we present a label-free non-faradaic impedimetric biosensor to detect bacterial cells using microfabricated gold interdigitated electrode (IDE). Silver nanoparticles (AgNP) are green synthesized using aqueous neem extract and characterized using Attenuated Total Reflectance- Fourier Transform Infrared spectra (ATR-FTIR), Dynamic Light Scattering (DLS), Scanning Electron Microscopy (SEM), and UV–Visible spectroscopy techniques. The synthesized AgNPs are well dispersed with an average size of 84 nm and showed an extensive antibacterial property indicated by a standard bioassay against Escherichia coli (E. coli). Gold IDEs are microfabricated by lithography on borosilicate glass wafers. The biofunctionalization of gold IDE is carried out using thiol‑gold covalent chemistry with mercaptohexanol (MCH). The self-assembled monolayer (SAM) of MCH facilitates drop-cast deposition of AgNP on the surface forming an MCH-AgNP. The functionalized IDE is electrochemically stable for further experiments and was validated by open circuit potential measurements. The objective of developing a label-free approach is confirmed by cyclic voltammetry analysis. Non-faradaic electrochemical impedance spectroscopy (nf-EIS) is carried out to detect E.coli cells suspended in water. The antibacterial property of AgNP is exploited to detect the decrease in cell concentration using nf-EIS. The impedance signatures corresponding to the trapping of cells are recorded with respect to time. Bacterial growth is a major challenge in maintaining water quality. The results demonstrated in this work would help to mitigate this problem effectively in a quick time without the need for skilled labor and sophisticated instruments required in traditional antibacterial testing

Part I: Non-faradaic electrochemical impedance-based DNA biosensor for detecting phytopathogen - Ralstonia solanacearum

Herein, we report for the first time the development of a label-free, non-faradaic, and highly sensitive DNA-based impedimetric sensor using micro-sized gold interdigitated electrodes (IDE) to detect a soil-borne agricultural pathogen Ralstonia solanacearum. A universal 30 oligomer single-stranded DNA (ssDNA) probe lpxC4 having specificity towards R. solanacearum is successfully immobilized on the surface of IDE along with mercaptohexanol. The electrochemical stability of the developed sensor surface is determined using open circuit potential measurements. The DNA probe immobilization protocol is validated using the changes configured on the surface of IDE by contact angle and ATR-FTIR analysis. The DNA target hybridization is detected using non-faradaic electrochemical impedance spectroscopy measurement with an ultra-low sample volume of 10 µL. The non-faradaic approach is verified by studying redox behavior using cyclic voltammetry. We investigate the hybridization of the surface-immobilized label-free probe with the complementary DNA targets obtained from infected eggplant saplings and cross-reactive studies with mismatched DNA strands. Our impedimetric sensor can detect target concentrations as low as 0.1 ng/µL. This standardization and detection of DNA hybridization serves as part I of the work and paves the way for further study in the detection of pathogenic field samples