Thermoplastic Substrates Research Articles

A Comparative Study of Microwave Welding Using Multiwalled Carbon Nanotubes and Silicon Carbide Nanowhiskers as Microwave Susceptors

Recently, microwave welding has arisen as an advanced joining method due to its versatility and rapid heating capabilities. Among others, microwave susceptors play a crucial role in microwave welding, as different classes of microwave susceptors have distinct microwave heating mechanisms. In this work, polypropylene (PP) was utilized as a thermoplastic substrate and two types of microwaves susceptors, namely multiwalled carbon nanotubes (MWCNTs) and silicon carbide nanowhiskers (SiC NWs), were studied for microwave welding. The susceptor was first dispersed in acetone to form susceptor suspension. Next, the susceptor suspension was deposited onto the targeted area on substrate and paired with another bare PP substrate. The paired sample was then exposed to 800 W microwave radiation in a microwave oven. Afterward, the welded joint was evaluated using a tensile test and scanning electron microscopy to determine its joint strength and cross-section microstructure. The results showed that the joint strength increased as the heating duration increased. The welded joint formed using MWCNTs achieved a maximum strength of 2.26 MPa when 10 s was used, while the SiC NWs-formed welded joint achieved a maximum strength of 2.25 MPa at 15 s. This difference in duration in forming a complete welded joint can be attributed to the higher microwave heating rates and thermal conductivity of MWCNTs. However, increasing the heating duration to 20 s caused severe deformation at the welded joint and resulted in low joint strength. Overall, this study highlights the significance of understanding the microwave heating mechanism of different susceptors and provides essential insight into the selection of a microwave susceptor for microwave welding.

Laser-induced graphene wet transfer technique for lab-on-chip applications

Due to its simple and cost-effective manufacturing process, Laser-Induced Graphene (LIG) has opened up possibilities for intriguing electronic applications in various contexts, including Lab-On-Chip scenarios. This attractive material can be produced on multiple organic substrates, but the most common are PolyImide sheets, which are generally less versatile than other plastic substrates. Moreover, they are opaque to multiple wavelengths in visible light, limiting their applicability in experiments that require a completely transparent material. For this reason, we developed a new and cheap transfer protocol, which exploits the partial solubility of thermoplastic substrates in a solvent to make them infiltrate the LIG, peeling it off from PolyImide. After focusing on transferring LIG on Poly Methyl Metacrylate substrates, the protocol has been optimized to minimize the transferred LIG (t-LIG) sheet resistance. The obtained material is then characterized by its morphology, electrode capabilities, and biocompatibility. Finally, t-LIG was simulated and used to apply an electric field in a Lab-On-Chip designed for microparticle manipulation by dielectrophoresis. The obtained results demonstrated the great potential of t-LIG in Lab-On-Chip and biological experiments, suggesting new exciting applications that rely on both optical and electrical investigations.

Characterization of atmospheric pressure plasma deposited (APPD) coatings to improve the friction behavior of thermoplastic surfaces

Achieving a significant friction reduction is crucial for using thermoplastic materials as substrates in tribological applications and presents an eligible alternative to the use of light metals. In this study, previously developed MoS2/graphite/zinc composite coatings, applied by an atmospheric pressure plasma deposition (APPD) process, were investigated to extend the understanding of their characteristics and the influence of the process and environmental parameters on friction behavior. Tribological tests were conducted in ambient conditions and at elevated temperatures (110 °C) to study the friction behavior under application-oriented conditions. The presence of atmospheric oxygen during the deposition process was shown to influence the durability of the coatings, which motivated the application of an inert gas atmosphere for the coating deposition. A novel shrouding plasma nozzle was introduced, which further lowered the friction coefficients. The oxidizing effect of the plasma spray deposition was studied with X-ray photoelectron spectroscopy to investigate the strong impact of the deposition current on the friction behavior and durability of the deposited coatings. Coating composition, morphology, and the effects of the tribological testing were evaluated using optical microscopy, 3D surface measurements, scanning electron microscopy, X-ray diffraction, and nanoindentation. The fabricated coatings with thicknesses in the 10 μm range and good adhesion on the polyamide substrate were stable under extended testing durations and at elevated temperatures and accomplished a significant friction reduction compared to the uncoated polyamide. Thus, APPD-fabricated MoS2/graphite/zinc coatings represent an excellent candidate for low-friction applications of thermoplastic substrates.

Utilization of cross‐correlation function for assessment of replication quality in ultrasonic embossing of microchannels on polymethyl methacrylate

AbstractUltrasonic embossing—a process where a horn vibrating at 20–30 kHz compresses on a thermoplastic substrate sitting on a mold to replicate the features on the mold to the substrate—is a promising method for fabricating microchannels on thermoplastics due to reduced cycle time and relatively low equipment cost. Replication quality in ultrasonic embossing has been investigated in the literature by primarily referring to the replication depth. However, this approach does not fully reflect the fidelity between the mold and the replicated feature, especially at the side walls, which are typically designed to be vertical in microchannels. We propose using cross‐correlation—a method that quantifies the similarity between two signals by measuring the overlap of their patterns—between the derivative of the mold profile and the embossed profile as a figure of merit that accurately reflects the fidelity of the side wall. For testing purposes, we embossed straight microchannels on polymethyl methacrylate (PMMA) using micron‐scaled protrusions on a brass mold fabricated by CNC milling. The mold comprised 100, 300, and 1000‐μm‐wide protrusions of same designed height of 300 μm, resulting in aspect ratios (AR) of 3, 1, and 1/3, respectively. Cross‐correlations between the derivatives of the profiles ranged between 0.50 and 1.00, while cross‐correlations between the profiles were greater than 0.97 in all cases, showing the sensitivity imposed by utilizing the derivatives. Setting average of all cross‐correlation values (0.8) as the quality threshold, we observed that high AR (3) features were replicated at low quality, while low AR (1/3) features were replicated at high quality, regardless of the process parameters. In replicating unit AR features, the process parameters were observed to affect the quality, where the combination of vibration time and pressure was the most significant compared to individual effects of the parameters.Highlights Parameters' effect on replication of varied aspect ratio features was assessed. Assessment was carried out by cross‐correlating mold and channel profiles. Cross‐correlating derivatives of profiles provide a more sensitive means. General rules for replication quality in ultrasonic embossing were driven.

Effect of Mold Materials Used During Hot Embossing on Feature Fidelity for Microfabrication in Cyclic Olefin Polymer (COP) Substrate

During the transition from research to market, the fabrication of microfluidic devices in thermoplastic substrates is inevitable. For short production runs of several hundred products, hot embossing is the typical method before moving on to a typically more expensive injection molding process for higher production volumes. In this work, we investigated the effect of mold material used during hot embossing on feature fidelity for microfabrication in cyclic olefin polymer (COP) substrate. Specifically, we designed a simple flow-focusing microfluidic device and fabricated three different molds using silicon wafer by deep reactive ion etching (DRIE), aluminum filled high temperature epoxy by soft lithography and aluminum by CNC milling. We performed hot embossing experiments with 2mm thick COP substrates and these three different molds using automatic bench top Carver hot press. Finally, we characterized the hot embossed substrates by optical and scanning electron microscopy. Fabrication results demonstrate that the mold material plays a big role in feature fidelity. Among the mold materials used, silicon substrate performed the worst based on defects after demolding. Epoxy and aluminum molds were similar in terms of microfabricated feature defects in the substrate which could be mostly attributed to their coefficient of thermal expansion (CTE). A mold material with a CTE closer to the thermoplastic will result in much better feature fidelity.

Methods to Improve Accuracy of Electronic Component Positioning in Thermoformed Electronics.

Three new methods for accurate electronic component positioning for thermoformed electronics are presented in this paper. To maintain the mechanical and electrical properties of printed-ink tracks, prevent deformation and stretching during thermoforming, and ensure reproducibility, the component positioning principle for all three proposed methods is based on keeping the temperature of some regions in the thermoplastic substrate less than the glass transition temperature of the thermoplastic carrier, to keep those regions resistant to plastic deformation. We have verified the accuracy of the different approaches by implementing these methods in a semi-sphere mold for positioning seven LEDs and one printed capacitive touch sensor. We compared the result of our fabrication processes with the typical fabrication process of in-mold electronics (direct printing on a thermoplastic foil and followed by a thermoforming step) and noticed that the sample produced by the typical process had tracks that were randomly stretched, tracks were not in a straight path after thermoforming and they were not electrically conductive. Furthermore, the final 3D position of the components was not reproducible sample by sample. However, with our proposed fabrication methods, the tracks and pads do not deform or expand during thermoforming and are electrically conductive after. Moreover, the round shape of the touch sensor remains the same as in the 2D design. Based on the results of the experiments, it appears that the proposed methods are capable of positioning electronic components with high precision in thermoformed electronics.

Largely Improving the Output Performance of Stretchable Triboelectric Nanogenerators via Thermo-Compressive Technology.

Stretchable triboelectric nanogenerators (TENGs) are widely applied in wearable and implantable electronics, smart medical devices, and soft robots. However, it is still a challenge to produce stretchable TENGs with both exceptional elasticity and output performance, which limits their application scope. In this work, high-performance stretchable TENGs are developed through a thermo-compression(TC) fabrication process. In particular, a poly(vinylidene fluoride) film is compactly bound to the elastic thermoplastic polyurethane substrate, which inherits excellent stretchability with a strain of up to 815%. Furthermore, owing to the large surface area, tight contact, and effective vertical transport of tribo-induced charges between the coupled fibrous tribo-layer and soft substrate, the TC composite film-based TENGs exhibit a greater output (2-4 times) than unlaminated film-based TENGs. Additionally, the broad universality of this method is proven using various tribo- and substrate materials. The proposed technology provides a novel and effective approach to conjointly boost the output and stretchability of TENGs, showing encouraging application prospects in self-powered wearable and flexible electronics.

Ultra-sensitive flexible pressure sensor with hierarchical structural laser-induced carbon nanosheets/carbon nanotubes composite film

Recently, laser induced carbon nanosheets (LICs) based flexible pressure sensors have received widespread attention. Introducing hierarchical microstructure is an effective method to improve the sensitivity of pressure sensors. However, implementing hierarchical microstructure on LICs film through a simple and low damage process remains a challenge. Herein, taking advantage of the reshaping characteristics of low melting point thermoplastic substrate styrene-isoprene-styrene (SIS) under laser thermal effects, a simple and one-step laser thermoforming process is used to spontaneously form surface microstructure on the LICs film during the formation of LICs. Therefore, a hierarchical structure composed of porous structure and surface microstructure was achieved on the LICs film through the one-step process. Furthermore, a hybrid strategy combining hierarchical microstructure with carbon nanotubes (CNTs)/LICs composite was proposed to improve the sensitivity of LICs based pressure sensor. Benefiting from the hierarchical structure of LICs and the composite conductive network constructed by CNTs and LICs, the LICs/CNTs@SIS sensor exhibits ultrahigh sensitivity of 1089 kPa−1 in 0–5 kPa and ultrahigh gauge factor of 1493 within the strain rate range of 20%–28%. Meanwhile, the sensor has good stability (>1400 cycles), response and recovery times of 23.8 ms and 25.9 ms, excellent reversibility, and 1220% elongation at break. Besides, the application of the sensor in physiological signal monitoring and pressure distribution detection indicates its great potential in flexible electronics.

Fabrication and Characterization of Hybrid and Tunable ZnO@Ag Flexible Thin Films Used as SERS Substrates

Flexible substrates have known increased popularity over rigid ones due to their use in surface-enhanced Raman scattering (SERS). They provide irregular surfaces, ideal for in situ sensing. In this context, we report the SERS performance of hybrid ZnO@Ag thin films deposited by magnetron sputtering (MS) on flexible, thermoplastic substrates. This physical deposition method is acknowledged for obtaining high-quality and reproducible ZnO films that can be embedded in (bio)sensing devices with various applications. Three types of thermoplastic-based, commercially available substrates with different glass transition temperatures (Tg) were chosen for the variation in flexibility, transparency, and thickness. Zeonor® (Tg = 136 °C, thickness of 188 μm) and two types of Topas (Topas®: Tg = 142 °C, thickness of 176 μm; Topas2: Tg = 78 °C, thickness of 140 μm) thermoplastic sheets are nonpolar and amorphous cyclo-olefin polymer (COP) and cyclo-olefin copolymers (COC), respectively. Their thicknesses and different values of Tg can greatly affect the topographical and roughness properties of films with small thicknesses and, thus, can greatly influence the enhancement of the Raman signal. The ZnO films deposited on top of Zeonor® or Topas® have identical morphological properties, as shown by the scanning electron microscopy (SEM) characterization. Subsequently, by using the MS technique, we tuned the thickness of the deposited silver (Ag) films in the range of 7–30 nm to assess the growth influence on the morphology and the SERS signal amplification of the substrates with and without the ZnO intermediate layer. The SEM analysis showed that the Ag atoms migrated both into the interstitial areas, filling the voids between the ZnO granular structures, and over the latter, forming, in this case, isolated Ag clusters. SERS analysis performed on the ZnO-Ag hybrid films using crystal violet (CV) molecule revealed a limit of detection (LOD) of 10−7 M in the case of 15 nm thick Ag/Zeonor® interlayer films ZnO and relative standard deviation (RSD) below 10%.

Effects of interface microstructure on adhesion of polyetheretherketone metallized by titanium cold spray

Titanium powders were cold sprayed onto polyetheretherketone (PEEK) to investigate the effects of interface microstructure on bonding. Process guidelines to achieve adherent metallic deposits via cold spray onto thermoplastics are scarce, and mechanisms for metal adhesion onto thermoplastic substrates are unclear. The formation of a transition layer where deposition changes from metal-on-polymer to metal-on-metal deposition can promote adhesion but requires a clearer understanding. The microstructural features of such transition layers provide insights into mechanisms that promote coating adhesion. Select features, including developed interfacial area ratio and gradation of thermal residual stress, correlated to adhesive strength values. The understanding of interlocking mesoscale features formed during cold spray informs the parameter selection for depositing metals onto thermoplastics with strong adhesion.

Sensitivity enhancement through geometry modification of 3D printed conductive PLA-based strain sensors

PurposeThe purpose of this study is to increasing the gauge factor, reducing the hysteresis error and improving the stability over cyclic deformations of a conductive polylactic acid (CPLA)-based 3D-printed strain sensor by modifying the sensing element geometry.Design/methodology/approachFive different configurations, namely, linear, serpentine, square, triangular and trapezoidal, of CPLA sensing elements are printed on the thermoplastic polyurethane substrate material individually. The resistance change ratio of the printed sensors, when loaded to a predefined percentage of the maximum strain values over multiple cycles, is recorded. Finally, the thickness of substrate and CPLA and the included angle of the triangular strain sensor are evaluated for their influences on the sensitivity.FindingsThe triangular configuration yields the least hysteresis error with high accuracy over repeated loading conditions, because of its uniform stress distribution, whereas the conventional linear configuration produces the maximum sensitivity with low accuracy. The thickness of the substrate and sensing element has more influence over the included angle, in enhancing the sensitivity of the triangular configuration. The sensitivity of the triangular configuration exceeds the linear configuration when printed at ideal sensor dimensional values.Research limitations/implicationsThe 3D printing parameters are kept constant for all the configurations; rather it can be varied for improving the performance of the sensor. Furthermore, the influences of stretching rate and nozzle temperature of the sensing material are not considered in this work.Originality/valueThe sensitivity and accuracy of CPLA-based strain sensor are evaluated for modification in its geometry, and the performance metrics are enhanced using the regression modelling.

Facile and adhesive-free method for bonding nanofiber membrane onto thermoplastic polystyrene substrate to fabricate 3D cell culture platforms.

Nanofiber (NF) membranes have been highlighted as functional materials for biomedical applications owing to their high surface-to-volume ratios, high permeabilities, and extracellular matrix-like biomimetic structures. Because many in vitro platforms for biomedical applications are made of thermoplastic polymers (TP), a simple and leak-free method for bonding NF membranes onto TP platforms is essential. Here, we propose a facile but leak-free localized thermal bonding method for integrating 2D or 3D-structured NF membrane onto a TP supporting substrate while preserving the pristine nanofibrous structure of the membrane, based on localized preheating of the substrate. A methodology for determining the optimal preheating temperature was devised based on a numerical simulation model considering the melting temperature of the NF material and was experimentally validated by evaluating bonding stability and durability under cell culture conditions. The thermally-bonded interface between the NF membrane and TP substrate was maintained stably for 3 weeks allowing the successful construction of an intestinal barrier model. The applicability of the localized thermal bonding method was also demonstrated on various combinations of TP materials (e.g., polystyrene and polymethylmethacrylate) and geometries of the supporting substrate, including a culture insert and microfluidic chip. We expect the proposed localized thermal bonding method to contribute toward broadening and realizing the practical applications of functional NF membranes in various biomedical fields.

A proposal for additively manufacturing printed circuits by employing concentrated solar energy

A novel method capable of generating printed circuits using concentrated solar energy (CSE) is proposed. The open literature has reported that no method employs CSE to obtain printed circuits additively. Based on the Mill & Fill method, a conductive material (Sn63Pb37) is deposited inside a trench milled on a thermoplastic substrate (PETG). The concentrated solar beam melts the conductive material to form a solid trace, while the substrate relaxes its structure and allows the inclusion of the path. The resulting hybrid joining between plastic and metal is like those obtained by LAMP (laser-assisted joining of metal-polymer). The 20 conducted tests found that the magnitude of direct solar radiation and the overall system efficiency are the most influential variables on the exposure time of the trace to the solar spot. Each test, with its conditions, was simulated in COMSOL Multiphysics software, and the temperatures obtained experimentally were compared with those obtained by simulation. This proposal is expected to serve as a bridge between both fields of study so that solar concentrators will be considered in the additive manufacturing of printed circuits and expand CSE's potential for developing consumer goods.

Highly Stretchable, Highly Sensitive, and Antibacterial Electrospun Nanofiber Strain Sensors with Low Detection Limit and Stable CNT/MXene/CNT Sandwich Conductive Layers for Human Motion Detection

With the rise of the concept of “Internet of Everything”, the development of wearable sensing devices is growing rapidly. Among them, crack-based strain sensors have received much attention due to their high sensitivity. However, the application of crack-based strain sensors has been limited by the relatively narrow sensing range. Here, a sandwich structure of a CNT/MXene/CNT sensing layer was realized on the flexible thermoplastic polyurethane substrate prepared by electrospinning, followed by layer-by-layer vacuum filtration. The two stable carbon nanotube (CNT) layers broaden the sensing range, and the strain sensor exhibits excellent sensing range (390%) and stability (3000 tensile tests). The strain sensor also shows excellent sensitivity (GF = 2159.5), low detection limit (0.05%), and fast response time (∼50 ms). The sensor is responsive to different movements when being applied to human motion detection, and the smart wearable device based on the strain sensor shows excellent performance in gesture language recognition. In addition, the antibacterial property of the conductive material inherently facilitates the wider application of the strain sensors.

Thermoplastic-based microfluidic chip bonding with PES hot melt adhesive film

ABSTRACT In this study, a low-cost and rapid bonding method for thermoplastic-based microfluidic devices is introduced. The thermoplastic substrate and cover plate were directly bonded with PES copolyester hot melt adhesive film. Compared with conventional bonding methods for thermoplastic chips, e.g. thermal fusion and chemical-assisted bonding, the proposed bonding process can be finished within minutes without sophisticated instruments or volatile chemical solvents. Several microfluidic devices were also fabricated and tested, the measured bonding strength is comparable to the conventional thermal fusion bonding method. The biocompatibility of the proposed bonding method was also evaluated by culturing bacteria in the PES adhesive covered culture dish. The proposed bonding method for thermoplastic-based microfluidic is especially suitable for the massive fabrication of POCT devices with advantages in processing speed, instrument requirement, cost, and bonding strength.

Highly Stretchable and Flexible Electrospinning‐Based Biofuel Cell for Implantable Electronic

AbstractWith the emerging demand of implantable microelectronics, it essentially requires the fully integrated and reliable power supplies. The study reports a stretchable and flexible electrospinning‐based glucose/O2 biofuel cell with glucose oxidase bioanode, Pt/C cathode and thermoplastic polyurethane substrate, which is capable for adapting to the various stresses and strains caused by individual movement. The rigid benzene rings and elastic chain segments of thermoplastic polyurethane ensure its superior tensile property. Furthermore, the stable covalent connections between the activated carbon nanotubes (CNTs‐COOH) and glucose oxidase inside 3D thermoplastic polyurethane network are established by amide reaction to ensure the rapid direct electron transfer of bioanode and stable power output of device in flexible environments. The biofuel cell exhibits an open circuit voltage of 0.575 V, and high‐power density of 57 µW cm−2 in 5 mM glucose. Moreover, the power‐generation properties of implantable biofuel cell keep steady, and its power density exhibits limited fluctuations on the dorsum of rat when bending, stretching, and twisting in 28 days. There is no obvious local inflammation or systemic abnormalities in rats. It satisfies the impressive biocompatible requirement, demonstrating the promising potential of electrospinning‐based biofuel cell as a robust self‐sustained power source for implantable electronics.

Intrinsically Stretchable Organic Solar Cells without Cracks under 40% Strain

AbstractIntrinsically stretchable organic solar cells (IS‐OSCs) have been recently spotlighted for their omnidirectional stretchability, seamless integrability to any surface, and facile fabrication. Due to these attributes, IS‐OSCs are ideal off‐grid power sources, especially for wearable electronics in real‐life. However, under human body elongation as high as ≈40%, cracks in IS‐OSCs are considered inevitable, and the origin of the mechanical failure is rarely identified. Herein, the crack‐initiation and the propagation mechanism are first clarified. Based on this, a crack‐free substrate/transparent electrode platform for stretchable electronics is also suggested. A double‐locking scheme, which reinforces the physical/chemical adsorption within the most mechanically fragile layer, a poly(3,4‐ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and also with thermoplastic polyurethane substrate, is introduced. As a result, the crack‐onset strain of double‐locked IS‐OSCs surpasses 40%, while that of pristine ones is less than 20%. The IS‐OSCs with the double‐locked system exhibits an efficient power conversion efficiency of 10.2%, and the absence of cracks allows the IS‐OSCs to maintain 79.7% of the initial PCE at 40% strain.

Surface Optimization of Components Obtained by Fused Deposition Modeling for Air-Plasma-Sprayed Ceramic Coatings

Additive manufacturing is an emerging disruptive 3D printing technology that is stimulating innovations in design and engineering, materials, and manufacturing thanks to the prospects of reducing cost and waste and increasing efficiency; in doing so, it presents the potential to have marked industrial, economic, and societal impacts. Thermoplastic polymers show some ideal characteristics for the most common additive manufacturing methods, and this aids in the improvement of the design accuracy and reliability and makes inroads for the customized manufacturing of high-design-flexibility polymer parts. Despite this, this material family is strongly sensitive to temperature, and one of the viable ways of limiting this weak point is surface coating with thermal barriers. The focus of this work was the optimization of an additive manufacturing process for producing thermoplastic components and to improve the adhesion of a thermal barrier coating on their surface. In detail, flat plate specimens of ULTEM 1010 were obtained by the fused deposition modeling technique by varying two significant surface parameters, the enhanced visible rasters and the visible raster air gap; then, their surfaces were covered by a thin ceramic coating by an air plasma spray system. A micro-geometric analysis that was conducted using a confocal microscope and the coating thickness measurements highlighted that a global larger roughness value, the presence of more flat peaks with a large area, and the complexity of the texture can be considered as supporting factors for improving the mechanical gripping and allowing a uniform adhesion of the coating powders on the thermoplastic substrate.

Effect of heat treatment on the performance of 3D printed thermoplastic polyurethane flexible substrates

Abstract3D printing technology combined with thermoplastic polyurethane (TPU) is increasingly being used in flexible electronics. However, the defects induced by 3D printing may degrade the mechanical properties of the TPU substrates significantly and result in the decrease in breaking elongation, tensile strength, and waterproof performance. In this article, we investigate the effect of heat treatment on improving the mechanical and waterproof properties of TPU substrate experimentally. The results show that heat treatment can effectively reduce the defects such as bubbles and pores inside the 3D printed TPU structure and increase the bonding area of the filament, and thus making the 3D printed TPU structure dense. After heat treatment at 180°C, the tensile strength and elongation at break of 3D printed TPU samples in the fiber direction (filling angle of 0°) increased by 67% and 38%, respectively. The tensile strength and elongation at break in the bonding direction (filling angle of 90°) increased by 100% and 75%. In addition, the waterproof performance of the samples has been enhanced, and the water contact angle of the surface has increased from 90.4°to 95.25°. Therefore, the heat treatment can effectively improve the mechanical properties and waterproof performance of 3D printed TPU samples.

Three-dimensional printed thermoplastic polyurethane on fabric as wearable smart sensors

The microstrip patch antenna (MPA) with a thermoplastic substrate has been widely used in wearable sensors primarily due to its lightweight, flexibility, strength, and compactness. But up till now, little has been conveyed on the use of three-dimensional (3D) printed thermoplastic polyurethane (TPU) on cotton-lycra woven (CLW) fabric-based substrate as a wearable sensor. This study presents a novel and scalable approach for characterizing, simulating, and fabricating the substrate for wearable sensor applications. In this study 3D printing of TPU on CLW fabric (70% cotton (on the warp side)-30% lycra (on the weft side) using fused filament fabrication (FFF) process) has been reported with a tradeoff between flexibility and strength (of a substrate for wearable sensor applications). The rheological, mechanical, morphological, four-dimensional (4D), and resonance frequency (RF) characterization of the substrate has been established. As regards rheological properties, the melt flow index (MFI) of primary (1°) recycled TPU was observed as 29.758 g/(10min). Further, the optimized 3D printing settings of TPU were obtained based on the mechanical testing (minimum stiffness, maximum peak strength (PS), maximum Young's modulus (E), and maximum strain energy (SE)) which comes out to be 225°C nozzle temperature, 18 mm/s printing speed and 60% infill density with a stiffness of 3.311 N/mm and PS of 9.628 MPa. The mechanical properties of TPU printed on stretched and unstretched CLW fabric were tested for lower stiffness (more flexibility). To ascertain the mechanical properties, porosity analyses of samples printed on CLW fabric have been performed based on scanning electron microscopy (SEM). For dielectric properties, and RF characterization, the ring resonator (RR) test was performed based on a Vector network analyzer (VNA). Finally, 4D characterization of the substrate was performed by applying a load from 0 to 25 N, resulting in programable RF output (in the industry scientific and medicine (ISM) band).