Bioinspired Passive Tactile Sensors Enabled by Reversible Polarization of Conjugated Polymers

Tactile perception plays a vital role for the human body and is also highly desired for smart prosthesis and advanced robots.Compared to active sensing devices,passive piezoelectric and triboelectric tactile sensors consume less power,but lack the capability to resolve static stimuli.Here,we address this issue by utilizing the unique polarization chemistry of conjugated polymers for the first time and propose a new type of bioinspired,passive,and bio-friendly tactile sensors for resolving both static and dynamic stimuli.Specifically,to emulate the polarization process of natural sensory cells,conjugated polymers(including poly(3,4-ethylenedioxythiophen e):poly(styrenesulfonate),polyaniline,or polypyrrole)are controllably polarized into two opposite states to create artificial potential differences.The controllable and reversible polarization process of the conjugated polymers is fully in situ characterized.Then,a micro-structured ionic electrolyte is employed to imitate the natural ion channels and to encode external touch stimulations into the variation in potential difference outputs.Compared with the currently existing tactile sensing devices,the developed tactile sensors feature distinct characteristics including fully organic composition,high sensitivity(up to 773 mV N^(−1)),ultralow power consumption(nW),as well as superior bio-friendliness.As demonstrations,both single point tactile perception(surface texture perception and material property perception)and two-dimensional tactile recognitions(shape or profile perception)with high accuracy are successfully realized using self-defined machine learning algorithms.This tactile sensing concept innovation based on the polarization chemistry of conjugated polymers opens up a new path to create robotic tactile sensors and prosthetic electronic skins.

Wireless contactless pressure measurement of an LC passive pressure sensor with a novel antenna for high-temperature applications

In this paper, a novel antenna is proposed for high-temperature testing, which can make the high-temperature pressure characteristics of a wireless passive ceramic pressure sensor demonstrated at up to a temperature of 600℃. The design parameters of the antenna are similar to those of the sensor, which will increase the coupling strength between the sensor and testing antenna. The antenna is fabricated in thick film integrated technology, and the properties of the alumina ceramic and silver ensure the feasibility of the antenna in high-temperature environments. The sensor, coupled with the ceramic antenna, is investigated using a high-temperature pressure testing platform. The experimental measurement results show that the pressure signal in a harsh environment can be detected by the frequency diversity of the sensor.

3D-printed microelectronics for integrated circuitry and passive wireless sensors

Three-dimensional(3D)additive manufacturing techniques have been utilized to make 3D electrical components,such as resistors,capacitors,and inductors,as well as circuits and passive wireless sensors.Using the fused deposition modeling technology and a multiple-nozzle system with a printing resolution of 30μm,3D structures with both supporting and sacrificial structures are constructed.After removing the sacrificial materials,suspensions with silver particles are injected subsequently solidified to form metallic elements/interconnects.The prototype results show good characteristics of fabricated 3D microelectronics components,including an inductor–capacitor-resonant tank circuitry with a resonance frequency at 0.53 GHz.A 3D“smart cap”with an embedded inductor–capacitor tank as the wireless passive sensor was demonstrated to monitor the quality of liquid food(e.g.,milk and juice)wirelessly.The result shows a 4.3%resonance frequency shift from milk stored in the room temperature environment for 36 h.This work establishes an innovative approach to construct arbitrary 3D systems with embedded electrical structures as integrated circuitry for various applications,including the demonstrated passive wireless sensors.

A Novel Readout System for Wireless Passive Pressure Sensors

This paper presents a novel readout system for wireless passive pressure sensors based on the inductively coupled inductor and cavity （LC） resonant circuits. The proposed system consists of a reader antenna inductively coupled to the sensor circuit, a readout circuit, and a personal computer （PC） post processing unit. The readout circuit generates a voltage signal representing the sensor＇s capacitance. The frequency of the reader antenna driving signal is a constant, which is equal to the sensor＇s resonant frequency at zero pressure. Based on mechanical and electrical modeling, the pressure sensor design based on the high temperature co-fired ceramic （HTCC） technology is conducted and discussed. The functionality and accuracy of the readout system are tested with a voltage-capacitance measurement system and demonstrated in a realistic pressure measurement environment, so that the overall performance and the feasibility of the readout system are proved.

A readout system for passive pressure sensors

This paper presents a readout system for the passive pressure sensors which consist of a pressure- sensitive capacitor and an inductance coil to form an LC circuit. The LC circuit transforms the pressure variation into the LC resonant frequency shift. The proposed system is composed of a reader antenna inductively coupled to the sensor inductor, a measurement circuit, and a PC post-processing unit. The measurement circuit generates a DC output voltage related to the sensor＇s resonant frequency and converts the output voltage into digital form. The PC post-processing unit processes the digital data and calculates the sensor＇s resonant frequency. To test the performance of the readout system, a sensor is designed and fabricated based on low temperature co-fired ceramic （LTCC）, and a series of testing experiments is carried out. The experimental results show good agreement with the impedance analyzer＇s results, their error is less than 2.5%, and the measured values are almost insensitive to the variation of readout distance. It proves that the proposed system is effective practically.

A Design of Remote-Controlled Chalkboard Eraser

Chalkboard erasers that are commonly used in many schools and education organizations have the poor ability in removing the dust off the chalkboard and collect them. The dust that is not collected will be taken into human bodies via inhalation, which will lead to respiratory diseases. Therefore, it is crucial to design a chalkboard eraser that can collect the dust effectively. If the eraser can be controlled both remotely and manually by people, it can further reduce the amount of dust taken in by human bodies. To achieve remote control, a micro-controller is needed to transfer the infrared radiation (IR) into signals that can control electric motors to move around on the chalkboard. Furthermore, the microfiber is also used as the cleaning material to improve the performance of dust cleaning and collecting. A vacuum pump is needed to create negative pressure between the eraser and the chalkboard so that the eraser can stick to it. The result shows a stronger ability in removing and collecting dust. With the help of the Arduino UNO board, the remote control is successfully achieved, and the eraser can move on the chalkboard freely according to the order.

Smart Building Design to Improve the Energy Consumption at an Office Room

Buildings are becoming smarter as a result of a variety of advanced technologies that enable energy management, optimal space utilization, and smart surveillance for safety, among other things. Energy-efficient smart building ideas and execution are of great interest and top priority due to the building’s occupants’ misused and high-power consumption. This paper addresses the design and execution of an energy management system that includes a solar power system for generating power for the building’s needs and a PIR-based automation system for efficient power use. This project was carried out at the Military Technological College (MTC) in Muscat, in the system engineering department’s offices. This project seeks to generate power for the building’s energy needs using solar photovoltaic panels and reduce energy consumption within the office using a PIR-based automation system. The results demonstrate that after the breakeven point (the time it takes to recoup the initial investment), it can provide power to the building for another 17 years. The calculations and practical results presented in this study approve that the system is extremely helpful.

Passive wireless smart-skin sensor using RFID-based folded patch antennas

Folded patch antennas were investigated for the development of low-cost and wireless smart-skin sensors that monitor the strain in metallic structures.When the patch antenna is under strain/deformation,its resonance frequency varies accordingly.The variation can be easily interrogated and recorded by a wireless reader.The patch antenna adopts a specially chosen substrate material with low dielectric attenuation,as well as an inexpensive off-the-shelf radiofrequency identification(RFID)chip for signal modulation.Since the RFID chip harvests electromagnetic power from the interrogation signal emitted by the reader,the patch antenna itself does not require other(internal)power sources and,thus,serves as a battery-less(passive)and wireless strain sensor.In this preliminary investigation,a prototype folded patch antenna has been designed and manufactured.Tensile testing results show strong linearity between the interrogated resonance frequency and the strain experienced by the antenna.Through experiments,the strain sensing resolution is demonstrated to be under 50με,and the wireless interrogation distance is shown to be over a few feet for this preliminary prototype.

Development of a surface acoustic wave wireless and passive temperature sensor incorporating reflective delay line

based on optimal design on the core element of the sensor,a wireless and passive surface acoustic wave（SAW）temperature sensor integrated with ID Tag was presented.A reflective delay line,which consists of a transducer and eight reflectors on YZ LiNbO3 substrate.Was fabricated as the sensor element,in which,three reflectors were used for temperature sensing,and the other five were for the ID Tag using phase encoding.Single phase unidirectional transducers（SPUDTs）and shorted grating were used to structure the sAW device,leading to excellent signal to noise ratio（SNR）.The performance of the SAW device was simulated by the coupling of modes（COM）prior to fabrication.Using the network analyzer,the response in time domain of the fabricated 434 MHz SAW sensor was characterized,the measured S11 agrees well with the simulated one,sharp reflection peaks,high signal/noise,and low spurious noise between the reflection peaks were observed.Using the radar system based on FSCW as the reader unit.the developed SAW temperature sensors were evaluated wirelessly.Excellent1 inearity and good resolution of士1℃ were observed.