A strain sensor has been fabricated from a polymer nanocomposite with multiwalled carbon nanotube (MWNT) fillers. The piezoresistivity
of this nanocomposite strain sensor has been investigated based on an improved three-dimensional (3D) statistical resistor network
model incorporating the tunneling effect between the neighboring carbon nanotubes (CNTs), and a fiber reorientation model. The
numerical results agree very well with the experimental measurements. As compared with traditional strain gauges, much higher sensitivity
can be obtained in the nanocomposite sensors when the volume fraction of CNT is close to the percolation threshold. For a small
CNT volume fraction, weak nonlinear piezoresistivity is observed both experimentally and from numerical simulation. The tunneling
effect is considered to be the principal mechanism of the sensor under small strains.

Tunneling effect in a polymer/carbon nanotube nanocompositestrain sensor

CRISPR-Cas12a-driven MXene-PEDOT:PSS piezoresistive wireless biosensor

Conductive hydrogels can be prepared by incorporating various conductive materials into polymeric network hydrogels. In recent years, conductive hydrogels have been developed and applied in the field of strain sensors owing to their unique properties, such as electrical conductivity, mechanical properties, self-healing, and anti-freezing properties. These remarkable properties allow conductive hydrogel-based strain sensors to show excellent performance for identifying external stimuli and detecting human body movement, even at subzero temperatures. This review summarizes the properties of conductive hydrogels and their application in the fabrication of strain sensors working in different modes. Finally, a brief prospectus for the development of conductive hydrogels in the future is provided.

Development of Conductive Hydrogels for Fabricating Flexible Strain Sensors.

Rapid advances in wearable electronics and mechno‐sensational human–machine interfaces impose great challenges in developing flexible and deformable tactile sensors with high efficiency, ultra‐sensitivity, environment‐tolerance, and self‐sustainability. Herein, a tactile hydrogel sensor (THS) based on micro‐pyramid‐patterned double‐network (DN) ionic organohydrogels to detect subtle pressure changes by measuring the variations of triboelectric output signal without an external power supply is reported. By the first time of pyramidal‐patterned hydrogel fabrication method and laminated polydimethylsiloxane (PDMS) encapsulation process, the self‐powered THS shows the advantages of remarkable flexibility, good transparency (≈85%), and excellent sensing performance, including extraordinary sensitivity (45.97 mV Pa−1), fast response (≈20 ms), very low limit of detection (50 Pa) as well as good stability (36 000 cycles). Moreover, with the LiBr immersion treatment method, the THS possesses excellent long‐term hyper anti‐freezing and anti‐dehydrating properties, broad environmental tolerance (−20 to 60 °C), and instantaneous peak power density of 20 µW cm−2, providing reliable contact outputs with different materials and detecting very slight human motions. By integrating the signal acquisition/process circuit, the THS with excellent self‐power sensing ability is utilized as a switching button to control electric appliances and robotic hands by simulating human finger gestures, offering its great potentials for wearable and multi‐functional electronic applications.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/advs.202104168

Ultra‐Sensitive, Deformable, and Transparent Triboelectric Tactile Sensor Based on Micro‐Pyramid Patterned Ionic Hydrogel for Interactive Human–Machine Interfaces

Flexible Hybrid Sensor Systems with Feedback Functions

Fabricating flexible pressure sensors with high sensitivity in a broad pressure range is still a challenge. Herein, a flexible pressure sensor with engineered microstructures on polydimethylsiloxane (PDMS) film is designed. The high performance of the sensor derives from its unique pyramid-wall-grid microstructure (PWGM). A square array of dome-topped pyramids and crossed strengthening walls on the film forms a multiheight hierarchical microstructure. Two pieces of PWGM flexible PDMS film, stacked face-to-face, form a piezoresistive sensor endowed with ultrahigh sensitivity across a very broad pressure range. The sensitivity of the device is as high as 383 665.9 and 269 662.9 kPa-1 in the pressure ranges 0-1.6 and 1.6-6 kPa, respectively. In the higher pressure range of 6.1-11 kPa, the sensitivity is 48 689.1 kPa-1, and even in the very high pressure range of 11-56 kPa, it stays at 1266.8 kPa-1. The pressure sensor possesses excellent bending and torsional strain detection properties, is mechanically durable, and has potential applications in wearable biosensing for healthcare. In addition, 2 × 2 and 4 × 4 sensor arrays are prepared and characterized, suggesting the possibility of manufacturing a flexible tactile sensor.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/advs.202000154

Engineered Microstructure Derived Hierarchical Deformation of Flexible Pressure Sensor Induces a Supersensitive Piezoresistive Property in Broad Pressure Range.

Method of data center dynamic environment monitoring system on basis of IOT (Internet Of Things) technology

Method of data center energy saving system based on virtual IT resource distribution technology

The invention discloses a data center energy saving system and a method The system comprises a plurality of intelligent power distribution cabinets, a plurality of air conditioners, a plurality of ventilation floors and a plurality of cabinets, the intelligent power distribution cabinets, the air conditioners, the ventilation floors and the cabinets are arranged in a data center, a plurality of servers are arranged in the cabinets, corresponding collecting devices are arranged in the data center and used for collecting corresponding data and uploading the collected data to a background, the background firstly establishes a three-dimensional model, a load power utilization and energy efficiency model, a line loss measurement model and a power quality measurement model of the data center according to the collected data, then the background draws a humiture cloud picture through modeling analysis and simulates a cool air flow distribution picture of the whole data center through a computational fluid dynamics (CFD) technology, and finally existing energy efficiency optimization scheme libraries in the background are integrated to determine an energy saving scheme On the premise that stable and efficient operating of the data center is guaranteed, energy saving is achieved, and simultaneously, after energy saving measures are taken, energy-saving effects of the whole data centerand whole operating conditions of the data center are real-timely estimated to achieve the optimum

Li Gang

Papers

Development of Conductive Hydrogels for Fabricating Flexible Strain Sensors.

Engineered Microstructure Derived Hierarchical Deformation of Flexible Pressure Sensor Induces a Supersensitive Piezoresistive Property in Broad Pressure Range.

Method of data center dynamic environment monitoring system on basis of IOT (Internet Of Things) technology

Method of data center energy saving system based on virtual IT resource distribution technology

Data center energy saving system and method