A Triband Slot Patch Antenna for Conformal and Wearable Applications

With the rapid development of wireless communication technology and the Internet of Things (IoT), wireless body area networks (WBAN) have been thriving. This paper presents a triband patch antenna with multiple slots for conformal and wearable applications. The proposed antenna operates at 5.8, 6.2, and 8.4 GHz. The antenna was designed with a flexible polyethylene terephthalate (PET) substrate, and the corresponding conformal tests and on-body performance were conducted via simulation. The antenna demonstrated promising gain and acceptable fluctuations when applied on curvature surfaces. The specific absorption rate (SAR) for on-body simulation also suggests that this antenna is suitable for wearable applications.

Numerical Study on Broadband Antireflection of Moth-Eye Nanostructured Polymer Film with Flexible Polyethylene Terephthalate Substrate

The application of moth-eye nanostructured polymer film on the flexible polyethylene terephthalate (PET) substrate is an effective way to improve its antireflection (AR) performance. However, many factors affect the AR properties of the moth-eye structure in the actual manufacturing process. Moreover, the antireflection research based on PET substrate has been relatively lacking compared with the silicon substrate. In this paper, we simulate and analyze the AR performance of the moth-eye nanostructured polymer film on PET substrate by using the finite-difference time-domain method within the wavelength range of 400–1100 nm. Simulation results show that the parabola-shaped moth-eye structure (PSMS) can suppress the Fresnel reflection significantly. Moreover, the height and filling ratios are the dominant factors that affect the AR performance of PSMS. Additionally, the base diameter, residual layer thickness, and the refractive index of PSMS polymer film also affect the reflectivity of PET slightly. As a result, an optimal PSMS with base diameter of 400 nm, height of 300 nm, and the hexagonal close-packed arrangement is appropriate, and the solar-weighted reflectivity of PET can be suppressed to 0.21%, which shows a prominent advantage over the bare PET (≈6%). Therefore, this research has promising potential for improving the optical performance of optoelectronic devices by using nanostructured polymer materials.

A Flexible Solar-blind Ultraviolet Photodetector based on Carbon Nanodots

A flexible solar-blind ultraviolet (UV) photodetector based on the carbon nanodots (CNDs) was fabricated on a polyethylene terephthalate (PET) substrate. The responsivity of 1.2 mA/W is obtained for 10 V applied bias under 254 nm illumination. Further, bending tests were carried out under the 0.2% strain, and the results showed that this flexible photodetector had stable characteristics and no obviously decrease of the photocurrent. The bending performances exhibit excellent potential for the fabrication of smart and flexible photodetectors.

Improving Printed Angle Sensor Performance by Compression-Tension Sensor Pair Compensation

Silver nanoparticle angle sensors are inkjet printed on a flexible PET substrate and implemented as pairs of compression and tension side folding individuals into a rigid experimental setup. Resulting combined signals improved the individual sensor responses due to their compensating characteristics, and gave the best performances in the existing literature in terms of linearity, sensor life-time, static and cyclic drift, hysteresis and dynamic dependency. Proposed method is promising for eliminating the major limitations on the printed sensor use in flexible hinges and paving the way to fully soft all-integrated foldable robots.

Improving Printed Angle Sensor Performance by Compression-Tension Sensor Pair Compensation

Silver nanoparticle angle sensors are inkjet printed on a flexible PET substrate and implemented as pairs of compression and tension side folding individuals into a rigid experimental setup. Resulting combined signals improved the individual sensor responses due to their compensating characteristics, and gave the best performances in the existing literature in terms of linearity, sensor life-time, static and cyclic drift, hysteresis and dynamic dependency. Proposed method is promising for eliminating the major limitations on the printed sensor use in flexible hinges and paving the way to fully soft all-integrated foldable robots.

Lamination Curing Method for Inkjet Printed Flexible Angle Sensors

In this paper we present the lamination curing as a stand-alone method to activate the silver nanoparticle (Ag NP) inkjet printed angle sensors on a 0.14 mm PET substrate, with a desktop printer. (With the term “lamination curing”, we refer passing the printed sample through a lamination machine, without any actual laminating purpose, only for curing.) We compared the method with the oven curing, which is the widest used method for the intended sensors, and found that lamination cured sensors give lower sheet resistance, lower fabrication uncertainty and more consistent angle sensing behaviors with higher sensing performance. Different curing parameters are inspected and a process under 3 minutes is achieved giving a 0.06 Ohm/square sheet resistance. For such a low sheet resistance, presented method has the lowest thermal curing time among all single layer Ag NP printing studies in the literature. An experimental model is presented for the sheet resistance - aspect ratio relation for both methods. Time dependent resistance shifts of the lamination cured sensors are also inspected and proved to be insignificant. We state lamination curing as an advantageous and reliable alternative to oven curing and other fast curing methods both for sensor and circuitry printing implementations.

Lamination Curing Method for Inkjet Printed Flexible Angle Sensors

In this paper we present the lamination curing as a stand-alone method to activate the silver nanoparticle (Ag NP) inkjet printed angle sensors on a 0.14 mm PET substrate, with a desktop printer. (With the term “lamination curing”, we refer passing the printed sample through a lamination machine, without any actual laminating purpose, only for curing.) We compared the method with the oven curing, which is the widest used method for the intended sensors, and found that lamination cured sensors give lower sheet resistance, lower fabrication uncertainty and more consistent angle sensing behaviors with higher sensing performance. Different curing parameters are inspected and a process under 3 minutes is achieved giving a 0.06 Ohm/square sheet resistance. For such a low sheet resistance, presented method has the lowest thermal curing time among all single layer Ag NP printing studies in the literature. An experimental model is presented for the sheet resistance - aspect ratio relation for both methods. Time dependent resistance shifts of the lamination cured sensors are also inspected and proved to be insignificant. We state lamination curing as an advantageous and reliable alternative to oven curing and other fast curing methods both for sensor and circuitry printing implementations.