Polydimethylsiloxane Material Research Articles

Polydimethylsiloxane diaphragm-based fiber ultrasonic sensor with high sensitivity and wide spectrum response range

In order to effectively enhance the sensitivity and response range of optical fiber Fabry–Pérot (FP) ultrasonic sensors, this article proposes an implementation method of an optical fiber FP ultrasonic sensor with a controllable cavity length and variable diaphragm. On the basis of optimizing the viscosity coefficient of the polydimethylsiloxane (PDMS) material, a PDMS diaphragm with the thickness ranging from 20 to 60 µm is fabricated on the end face of a Φ200/128 µm hollow glass tube using a multiple transfer method. Then, a piece of Φ125 µm single-mode optical fiber is threaded into the hollow glass tube from the other end and encapsulated to form an optical fiber FP ultrasonic sensor based on a PDMS diaphragm. The intensity of the corresponding ultrasound signal and its spectral characteristics can be inverse-analyzed by detecting the FP interference spectra formed on the fiber end and the PDMS diaphragm surface under the action of dynamic ultrasound signals. The experimental results show that the highest ultrasonic detection frequency response of the proposed PDMS diaphragm optical fiber FP ultrasonic sensor can reach 430 kHz and the signal-to-noise ratio can reach up to 70 dB. The above-mentioned results indicate that the optical fiber FP ultrasonic sensor with a PDMS diaphragm proposed in this article has obvious advantages in terms of sensitivity and response range.

Polymer Optical Fiber-Embedded Force Sensor System for Assistive Devices With Dynamic Compensation

This paper presents the development and the performance analysis of a force sensor using a novel high stretchable polymer optical fiber (POF) fabricated using the light polymerization spinning (LPS) fiber. The system consists of an LPS-POF fiber encapsulated in a flexible material polydimethylsiloxane (PDMS), in addition to a light source and a photodetector. The sensor was characterized by using a commercial 3-axis force sensor K3D60a ±500N/VA (ME Systeme, Germany). Since the LPS-POF and PDMS are viscoelastic materials, tests with loading and unloading cycles were performed to evaluate the sensor response. A viscoelasticity compensation model was proposed to decrease the errors and the sensor phase delay provoked by the viscoelastic behavior. In addition, the LPS-POF force sensor was applied on two different applications, as a gait perturbation system for balance assessment and as a walking cane for gait assistance. Results showed that proposed sensor presents a linear response, with determinant coefficient ( R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) of 0.9974, and high sensitivity ( S=40N/V). However, the unload time presented high phase delay and errors, corroborating the viscoelastic behavior. Compensated response presented lower hysteresis, leading to a decrease of the root mean square error (RMSE) of approximately 65%. Moreover, numerical integration was used as performance metric for the results of both applications and presented a decrease of 48% in the first application and up to 46% in the second application when used viscoelasticity compensation. The proposed sensor is small and versatile for different applications, and presents simple fabrication, data acquisition and processing.

Design and Displacement Analysis of Three different Cantilever based MEMS Piezoresistive Pressure Sensor with Polymer (PDMS/PMMA) Thin Flim

This paper mainly focuses on to get high displacement from polymer based piezoresistive cantilever for MEMS/NEMS pressure sensor applications. The displacement has been analyzed and compared with three different cantilever using PDMS (Poly dimethyl siloxane) and PMMA (Poly methyl methacrylate) materials. The p-type silicon piezoresistors connected the form based on wheat stone bridge to get high sensible pressure sensor with respect to low response. An according to get high displacement, obviously the other performance of parameters such as stress, strain gets high range. So, this analyzed cantilever structure used to design a pressure sensor with high sensitivity. The design and simulation are done by using COMSOL Multiphysics.

Blood repellent superhydrophobic surfaces constructed from nanoparticle-free and biocompatible materials

Durable and environment friendly superhydrophobic surfaces are needed for a set of important applications. Biomedical applications, in particular, impose stringent requirements on the biocompatibility of the materials used in the fabrication of superhydrophobic surfaces. In this study, we demonstrate the fabrication of mechanically durable superhydrophobic surfaces via an in-situ structuring strategy starting from natural carnauba wax and biocompatible polydimethylsiloxane (PDMS) materials. The transfer of the structure of the paper to a free-standing PDMS film provided the microscale structure. On top of this structured surface, the wax was spray-coated, initially resulting in a relatively homogeneous film with limited liquid repellence. The key in achieving superhydrophobicity was rubbing the surface for in-situ generation of a finely textured wax coating with a water contact angle of 169° and a sliding angle of 3°. The hierarchically structured surface exhibits mechanical robustness as demonstrated with water impact and linear abrasion tests. We finally demonstrate repellence of the surfaces against a range of blood products including platelet suspension, erythrocyte suspension, fresh plasma, and whole blood.

Evaluation of the Effects of Solvents Used in the Fabrication of Microfluidic Devices on Cell Cultures.

Microfluidic microphysiological systems (MPSs) or “organs-on-a-chip” are a promising alternative to animal models for drug screening and toxicology tests. However, most microfluidic devices employ polydimethylsiloxane (PDMS) as the structural material; and this has several drawbacks. Cyclo-olefin polymers (COPs) are more advantageous than PDMS and other thermoplastic materials because of their low drug absorption and autofluorescence. However, most COP-based microfluidic devices are fabricated by solvent bonding of the constituent parts. Notably, the remnant solvent can affect the cultured cells. This study employed a photobonding process with vacuum ultraviolet (VUV) light to fabricate microfluidic devices without using any solvent and compared their performance with that of solvent-bonded systems (using cyclohexane, dichloromethane, or toluene as the solvent) to investigate the effects of residual solvent on cell cultures. Quantitative immunofluorescence assays indicated that the coating efficiencies of extracellular matrix proteins (e.g., Matrigel and collagen I) were lower in solvent-bonded COP devices than those in VUV-bonded devices. Furthermore, the cytotoxicity of the systems was evaluated using SH-SY5Y neuroblastoma cells, and increased apoptosis was observed in the solvent-processed devices. These results provide insights into the effects of solvents used during the fabrication of microfluidic devices and can help prevent undesirable reactions and establish good manufacturing practices.

PDMS material embrittlement and its effect on machinability characteristics by cryogenic abrasive air-jet machining

Abstract The use of cryogenic abrasive jet machining (CAJM) technology for polydimethylsiloxane (PDMS) materials is increasing rapidly due to its high material removal rate and high surface quality. However, how the material properties of PDMS affect the machining properties under cryogenic conditions is still an unsolved problem. Firstly, the thermodynamic and mechanical properties of PDMS materials are studied by dynamic thermo-mechanical analysis and universal material testing. The results show that the PDMS material’s embrittlement temperature is 126 K. Secondly, evaluation of cooling temperature of PDMS during CAJM shows that the machined area has reached embrittled state. Thirdly, the effect of PDMS material’s embrittlement on the machining behaviour is studied. The experimental results show that the PDMS material exhibit increased abrasive erosion at medium-angle under cryogenic conditions and shows a semi-brittle wear mechanism. Furthermore, the erode surface’s roughness is evaluated. The result shows that the roughness decreases with decreasing air pressure at the same impact angle; with increasing impact angle, the roughness shows a trend of increase initially and then decreases. This work shows that the PDMS material’s embrittlement and the erosion response behaviour during CAJM are due to the combined effects of thermo-mechanical properties and material removal mechanisms, providing a better understanding of CAJM technology.

Sensitive, Color-Indicating and Labeling-Free Multi-Detection Cholesteric Liquid Crystal Biosensing Chips for Detecting Albumin.

A novel device for cholesteric liquid crystal (CLC)-based microfluidic chips, accommodated in a polydimethylsiloxane material, was invented. In this device, the reorientation of the CLCs was consistently influenced by the surface of the four channel walls and adjacent CLCs. When the inside of the microchannel was coated with the alignment layer, the CLCs oriented homeotropically in a focal conic state under cross-polarizers. Once antigens had bound onto antibodies immobilized onto the orientation sheet-coated channel walls, the light intensity of the CLC molecules converted from a focal conic state to a bright planar state caused by disrupting the CLCs. By means of utilizing pressure-propelling flow, the attachment of antigen/antibody to the CLCs should be detectable within consecutive sequences. The multi-microfluidic CLC-based chips were verified by measuring bovine serum albumin (BSA) and immune complexes of pairs of BSA antigen/antibody. We showed that the multiple microfluidic immunoassaying can be used for measuring BSA and pairs of antigen/antibody BSA with a detection limit of about 1 ng/mL. The linear range is 0.1 μg/mL–1 mg/mL. A limit of immune detection of pairs of BSA antigens/antibodies was 10 ng/mL of BSA plus 1000 ng/mL of the anti-BSA antibodies was observed. According to this innovative creation of immunoassaying, an unsophisticated multi-detection device with CLC-based labeling-free microfluidic chips is presented.

Effects of Binder and Substrate Materials on the Performance and Reliability of Stretchable Nanocomposite Strain Sensors.

In stretchable strain sensors, highly elastic elastomers such as polydimethylsiloxane (PDMS), Ecoflex, and polyurethane are commonly used for binder materials of the nanocomposite and substrates. However, the viscoelastic nature of the elastomers and the interfacial action between nanofillers and binders influence the critical sensor performances, such as repeatability, response, and hysteresis behavior. In this study, we developed a stretchable nanocomposite strain sensor composed of multiwalled carbon nanotubes and a silicone elastomer binder. The effects of binder and substrate materials on the repeatability, response, hysteresis behavior, and long-term endurance of the strain sensors were systematically investigated using stretching, bending, and repeated cyclic bending tests. Three different binder and substrate materials including PDMS, Ecoflex, and a mixture of PDMS/Ecoflex were tested. The stretchable strain sensors showed an excellent linearity and stretchability of more than 130%. Therefore, the long-term endurance of the strain sensors fabricated with Ecoflex binder should be improved. The strain sensors fabricated with Ecoflex binder showed a relatively large variation in electrical resistance during 10,000-cycle bending tests and repeatability errors at large bending angles. The strain sensors fabricated with PDMS binder showed repeatability errors at small bending angles and a slight response delay of 1 second. On the contrary, the strain sensors fabricated with a mixture of PDMS/Ecoflex binder showed excellent repeatability and response characteristics. The PDMS material showed hysteresis behavior; therefore, the strain sensors fabricated with PDMS binder on PDMS substrate exhibited a large hysteresis behavior in the first stretch-release cycle. It was found that the hysteresis behavior of the strain sensors was mainly dependent on substrate materials than on binder materials. The stretchable strain sensors made of the mixture of PDMS/Ecoflex exhibited excellent repeatability, response, hysteresis behavior, and excellent capability in detecting finger and wrist bending.

A facile preparation of the superhydrophobic polydimethylsiloxane materials and its performances based on the supercritical fluid foaming

AbstractThe supercritical foaming (SCF) method was proposed to conveniently fabricate superhydrophobic polydimethylsiloxane (PDMS) surface. The effect of foaming parameters on the cellular structure, wettability, mechanical properties and thermal properties was investigated. This work indicates that the microstructure plays an important role in the superhydrophobicity of the PDMS materials. When the cell size and cell wall size, respectively, reach to 103.6 and 29.7 μm, the water contact angle (WCA) of the microcellular PDMS foams can achieve the maximum value 158°, and the air occupies about 90.6% of the contact areas. Meanwhile, the tensile strength of superhydrophobic PDMS materials can reach to 0.81 MPa, indicating that the superhydrophobic PDMS materials are useful. Moreover, the superhydrophobic PDMS materials show good thermal stability and excellent adiabatic property. And the method is simple and convenient, which can be used for the preparation of the superhydrophobic surfaces.

Thermoelectric performance and stress analysis on wearable thermoelectric generator under bending load

With the growing popularity of flexible micro-electronics and health-monitoring sensors, wearable flexible thermoelectric generators (TEGs) are receiving attention due to their ability to convert body heat into electricity. In this study, a three-dimensional model of wearable TEGs encapsulated in the PDMS material is established based on the nonlinearly coupled thermoelectric transport constitutive law, large deformation of materials, and the 3-parameter Mooney-Rivlin nonlinear hyperelastic constitutive law of polydimethylsiloxane (PDMS) material. The thermoelectric performance and mechanical reliability of the wearable TEG are investigated under the bending load by employing finite element method. A comparison between numerical results and experimental data is conducted for validation of the model. Effects of the leg shape, filling factor and height of the legs are examined on the thermoelectric performance and mechanical reliability of the wearable TEGs. The optimized dimensions of wearable thermoelectric generators are obtained and analyzed. The results show that, thermoelectric performance and flexibility of the wearable TEG can be enhanced by increasing the number of thermocouples in the TEG. The results of this paper provide useful suggestions for the structural design and practical application of wearable TEGs encapsulated in PDMS materials.

Highly interconnected porous PDMS/CNTs sandwich sponges with anti-icing/deicing microstructured surfaces

Three-dimensional flexible porous polydimethylsiloxane (pPDMS) materials are widely used in electronics due to their relatively large specific surface area, and so maintaining the electric charge at a high-humidity atmosphere is an issue that must be addressed. A method for combining centrifuging and hot embossing was proposed for rapid mass production of highly interconnected pPDMS sandwich sponges with microstructure on top layer. As optimized sacrificial templates, the salts were rearranged in the PDMS by this method, and so the high connectivity facilitated salts dissolving in 3 h, which greatly improved the efficiency of the whole fabrication period. The weight ratio of PDMS to salt was 1.0–3.5, and the porosity can be kept at ~ 70%. The combination of micron-scale truncated cones and highly interconnected pore structure endowed the sponge surface with a contact angle of up to ~ 153° and ice adhesion strength as low as ~ 6.78 kPa. The strategy to combine passive anti-icing with active deicing is to prepare PDMS/CNTs sandwich sponges with microstructure on top layer. For the PDMS/CNTs (7 wt%) sandwich sponge, the results show that the elongation at break is as high as ~ 161% and the stress is as low as ~ 23 kPa. Besides, its surface temperature rose rapidly from 25 to 100 °C in 10 s through far-infrared light (808 nm) irradiation, achieving a remote deicing effect. The superhydrophobic and anti-icing/deicing sponges with high toughness property are expected to be of use for further applications.

Frequency-dependent focal length of a plano-spherical convex subsonic index lens

This study aims to investigate the frequency-dependent characteristics of the focal length of an acoustic lens made of a material with a frequency-dependent acoustic refractive index (ARI). For this purpose, an exchangeable plano-spherical convex subsonic index lens (PSCSIL) was fabricated using a polydimethylsiloxane (PDMS) material. The ARI of the lens material was evaluated via the tone-burst through-transmission method over the frequency range of 1–10 MHz. The frequency dependence of the focal length of the fabricated PSCSIL was evaluated through graphical analysis of the acoustic field scanned by a hydrophone as well as of that simulated using the finite element method. The measured ARI and focal length were observed to be dependent on frequency. The simulated and measured focal lengths of the PSCSIL exhibited a great discrepancy with their respective values predicted using the conventional focal length equation. This discrepancy was further studied using the ray-tracing method and is described in the discussion section. In conclusion, the spherical curvature of PSCSIL does not induce the convergence of rays to meet in a point. The ray tracing method does not take into account the phase complexity of the near-field region inside the lens. This causes the actual focal length to be shorter than the predicted one.

Investigation on the adhesive contact and electrical performance for triboelectric nanogenerator considering polymer viscoelasticity

The triboelectric nanogenerator (TENG) is a new mechanical energy harvesting technology in which the typical viscoelastic material polydimethylsiloxane (PDMS) is widely used. Micro-/nano-textures are often fabricated on the PDMS surface to enhance the electrical performance of TENG. As the contact region decreases to micro/nano scale, the adhesive forces become dominant. However, there is still a lack of contact mechanics model considering both material viscoelasticity and the adhesive forces to guide the surface texture design. In this paper, the explicit data-fitting formulas based on the fractional derivative Zener model are firstly derived to identify the viscoelastic constitutive parameters, which can not only avoid the influence of the initial contact point, but also ensure the accurate conversion between the creep compliance and the relaxation modulus function. Then a viscoelastic-adhesive contact model based on the fitted constitutive parameters is established, and the numerical algorithms such as bi-conjugate stabilized (Bi-CGSTAB) method and fast Fourier transform (FFT) technique are employed to analyze the effects of material viscoelasticity and texture sizes on the contact and electrical performance. It is shown that, compared with results from the elastic-adhesive contact model, the contact area ratio based on the viscoelastic-adhesive contact model is significantly larger, which is much closer to the experimental results. Among the selected sizes of pyramid texture, the higher electrical performance can be obtained from the textures with a smaller pitch and a larger width under the heavier applied load. This study can provide a theoretical reference for the design of viscoelastic surface texture of TENG.

Multiplex detection of blood-borne pathogens on a self-driven microfluidic chip using loop-mediated isothermal amplification

Detection of blood-borne pathogens such as hepatitis C virus (HCV), hepatitis B virus (HBV) and human immunodeficiency virus (HIV) is essential to ensure the safety of blood transfusion. However, traditional PCR-based pathogen nucleic acid detection methods require relatively high experimental facilities and are difficult to apply in areas with limited resources. In this study, a self-driven microfluidic chip was designed to carry out multiplex detection of HBV, HCV and HIV by using loop-mediated isothermal amplification (LAMP). Benefitting from the air permeability of the polydimethylsiloxane material, the chip could accomplish sample loading within 12min driven by the pressure difference between the reaction chambers and vacuum chambers in the chip without using pumps or any injection devices. Multiplex detection is achieved by presetting LAMP primers specific to different targets in different reaction chambers. Calcein was used as an indicator to indicate the positive amplification reaction, and the result can be recorded by a smartphone camera. After 50min of isothermal amplification at 63°C, 2 copies/μL of HBV, HCV and HIV target nucleic acids could be detected. The results of HBV detection of 20 clinical plasma samples by using the chip are consistent with that of the qPCR-based kit, indicating that the LAMP-based self-driven chip has the clinical application potential for blood-borne pathogen detection, especially in resource-limited areas.

Printability and mechanical performance of biomedical PDMS-PEEK composites developed for material extrusion

Polydimethylsiloxane (PDMS) materials are widely adopted in the manufacture of facial prostheses, lab-on-chip devices and scaffolds for soft-tissue engineering applications; however, their processing by additive manufacturing (AM) has proved challenging. Liquid silicone rubbers (LSRs) are favoured for their high shape fidelity when cast, but their low viscosity and surface tension often prevent self-support, post-extrusion. Poly(ether) ether ketone (PEEK) particle reinforcement through interfacial bonding has proven to enhance key properties of PDMS, expanding their end-use functionality. Still, the impact of such particles on the printability of LSR-PDMS is not explored. In this study, for the first time, solvent-free biocompatible PDMS-PEEK composites (up to 30 wt% PEEK) were successfully characterised for material extrusion (ME) printing. Rheological analysis confirmed shear-thinning of all PDMS-PEEK composites under applied load (within the tolerances of the printer) and dominant storage moduli at rest (i.e. prints can self-support), considered highly desirable for ME-based printing. Attained rheological datasets were used to guide initial printability studies, which revealed finer track fidelity with rising fractional content of PEEK, at comparable print speed and displacement values. Composites with higher PEEK content demonstrated significant increases in Shore A hardness and stiffness (in tension and compression) in bulk form. Last but not least, enhanced shape fidelity (thanks to PEEK reinforcement) and geometrical autonomy further expanded the manufacturing freedom of PDMS, whereby infill density could be controlled in order to increase the range of mechanical performance, previously unachievable with conventional casting fabrication. Fundamentally, this could lead to the manufacture of bespoke spatially graded multi-material structures and devices that could be used to replicate the heterogenous properties of soft human tissues and in other advanced material applications.

Surface wave interactions with submerged horizontal viscoelastic sheets

In this study, the surface wave interactions with submerged horizontal viscoelastic sheets of varying rheological properties are investigated both experimentally and analytically. In the experiments, we adopt the novel development in preparing finite length viscoelastic sheets with different rheological properties using oil-doped polydimethylsiloxane (PDMS) materials reported earlier in Sree et al. (2017, 2018). The wave interactions with the submerged viscoelastic sheets are quantified using ultrasonic sensors at different locations in terms of the reflection and transmission behavior. The experimental results show that the wave-sheet interactions are complex. The wave pattern at the submerged sheet region significantly depends on its rheological properties. For larger submergence, a standing wave pattern with primarily lower order modes develops along the sheet with a significant reduction of transmitted wave energy past the sheet region for shorter period waves. An almost complete cutoff (up to 99% reduction in wave energy transmission) occurs with the flexible sheet held close to the mean water level (MWL), while 50-90% reduction in wave energy transmission is recorded with the stiffer sheets. An analytical study is also carried out under the assumption of small amplitude water wave theory. The sheet is modeled based on the viscoelastic representation of the Voigt model and the analytical problem is solved using the domain matching technique. The profiles of surface wave as well as sheet displacement are well predicted by the analysis compared to the experimental measurements. However, the displacement amplitude is underestimated due to the fixed end conditions assumed. The predicted dispersion relation for the surface waves also agrees well with the experimental results for the shorter period waves, however larger discrepancies are observed with longer wave periods. In addition, the experimental results are up to one order of magnitude higher with respect to wave reflection. Thus, further improvement is needed in the future for the analysis to better represent the surface wave interactions with submerged viscoelastic sheets.

Microfluidics and organ-on-a-chip technologies: A systematic review of the methods used to mimic bone marrow.

Bone marrow (BM) is an organ responsible for crucial processes in living organs, e. g., hematopoiesis. In recent years, Organ-on-a-Chip (OoC) devices have been used to satisfy the need for in vitro systems that better mimic the phenomena occurring in the BM microenvironment. Given the growing interest in these systems and the diversity of developed devices, an integrative systematic literature review is required. We have performed this review, following the PRISMA method aiming to identify the main characteristics and assess the effectiveness of the devices that were developed to represent the BM. A search was performed in the Scopus, PubMed, Web of Science and Science Direct databases using the keywords ((“bone marrow” OR “hematopoietic stem cells” OR “haematopoietic stem cells”) AND (“organ in a” OR “lab on a chip” OR “microfluidic” OR “microfluidic*” OR (“bioreactor” AND “microfluidic*”))). Original research articles published between 2009 and 2020 were included in the review, giving a total of 21 papers. The analysis of these papers showed that their main purpose was to study BM cells biology, mimic BM niches, model pathological BM, and run drug assays. Regarding the fabrication protocols, we have observed that polydimethylsiloxane (PDMS) material and soft lithography method were the most commonly used. To reproduce the microenvironment of BM, most devices used the type I collagen and alginate. Peristaltic and syringe pumps were mostly used for device perfusion. Regarding the advantages compared to conventional methods, there were identified three groups of OoC devices: perfused 3D BM; co-cultured 3D BM; and perfused co-cultured 3D BM. Cellular behavior and mimicking their processes and responses were the mostly commonly studied parameters. The results have demonstrated the effectiveness of OoC devices for research purposes compared to conventional cell cultures. Furthermore, the devices have a wide range of applicability and the potential to be explored.

Polydimethylsiloxane (PDMS) microfluidic modifications for cell-based immunofluorescence assay

Polydimethylsiloxane (PDMS) is a hydrophobic elastomer commonly used for microfluidic fabrication. PDMS has to be modified to improve its hydrophilicity and thus inhibits non-specific protein adsorption. This work evaluates the modification materials for the development of microfluidic cell-based immunofluorescence (IF) assay. In cell-based IF assay, PDMS is modified not just to inhibit the adsorption of non-specific florescent-conjugated protein that causes the elevation of background signal, but also to firmly support cell adhesion for subsequent immunostaining procedure. PDMS materials modified by three regular modification materials consisting of an extracellular matrix (poly-L-lysine; PLL), a hydrophilic polymer (polyvinyl alcohol; PVA) and a non- ionic surfactant (pluronic F127) were compared with each other based on hydrophilicity improvement, minimization of non-specific background signal, and enhancement of human embryonic kidney (HEK) cell adhesion. Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) analysis confirms that all modification materials are successfully immobilized on the PDMS surfaces. Due to its antifouling mechanism, pluronic modification greatly improves the hydrophilicity of the PDMS and inhibits non-specific protein adsorption. Even though the hydrophilicity and non-specific protein adsorption resistivity of the PDMS modified with PLL did not significantly differ from those of the unmodified PDMS, PLL modification obviously promotes HEK cell adhesion. Negative control and Myelin Oligodendrocyte Glycoprotein (MOG) expressing HEK cells were immobilized in microfluidics for IF assay evaluation. Results demonstrate that positive MOG expressing cells can be selectively stained by anti-MOG IgG antibody within 1 h at room temperature. Microfluidic platforms also enhance immobilized cell distribution, which compatibly supports single-cell analysis technique.

Modeling and Fabrication of a Piezoelectric Artificial Cochlea Electrode Array With Longitudinal Coupling

In this study, inspired from human cochlea, we propose an artificial basilar membrane structure based on an array of gold electrodes microfabricated along the opposite surfaces of a piezoelectric continuum. The proposed piezoelectric continuum features an isosceles trapezoidal geometry and is situated atop an elastomer matrix with embedded electrode grooves and a duct. At first, a detailed analytical model is presented, which formulates the continuum’s planar deflection equation, governing its elastodynamic behavior. Subsequently, in order to verify the analytical outcomes, a multiphysics finite-element analysis is performed in COMSOL®. Both analytical and numerical models demonstrate desired frequency selectivity akin to the capability of a biological basilar membrane. Subsequently, a proof-of-concept model of the proposed structure is custom-fabricated through standard photo- and soft lithography techniques using Polyvinylidene Difluoride (PVDF), gold, and Polydimethylsiloxane (PDMS) materials. Finally, the fabricated artificial basilar membrane that is intended to be used as a broad band sensor, and artificial cochlea for seamless human-robot interaction is experimentally characterized using a custom-built acoustic exciter, and its effective performance is validated within the frequency range of 3 kHz to 8 kHz.

Direct Synthesis of Peptide-Containing Silicones: A New Way to Bioactive Materials.

A simple and efficient way to synthesize peptide-containing silicone materials is described. Silicone oils containing a chosen ratio of bioactive peptide sequences were prepared by acid-catalyzed copolymerization of dichlorodimethylsilane, hybrid dichloromethyl peptidosilane, and Si(vinyl)- or SiH-functionalized monomers. Functionalized silicone oils were first obtained and then, after hydrosilylation cross-linking, bioactive polydimethylsiloxane (PDMS)-based materials were straightforwardly obtained. The introduction of an antibacterial peptide yielded PDMS materials showing activity against Staphylococcus aureus. PDMS containing RGD ligands showed improved cell-adhesion properties. This generic method was fully compatible with the stability of peptides and thus opened the way to the synthesis of a wide range of biologically active silicones.