Herein we report a self-powered multimodal temperature and force sensor based on the reverse electrowetting effect and the thermogalvanic effect in a liquid droplet. The deformation of the droplet and the temperature difference across the droplet can induce an alternating pulse voltage and a direct voltage, respectively, which is easy to separate/analyze and can be utilized to sense the external force and temperature simultaneously. In addition, an integral display system that can derive information from external temperature/force concurrently is constructed. Combined with advantages of excellent sensing properties and a simple structure, the droplet sensor has promising applications in a wide range of intelligent electronics.
Theoretical studies are presented for the band structures of bulk waves in a two-dimensional composite structure consisting of rectangular piezoelectric ceramics placed periodically in an epoxy substrate. The dependences of the widths and starting frequencies of the first bandgaps (FBGs) on the filling fraction and the ratio of length to width of the embedded section are calculated for different polarized directions of the piezoelectric ceramics and different phononic structures. Our research shows that the FBG depend strongly on the polarized directions, the phononic structures, the filling fraction and the ratio of length to width, respectively. Therefore, one can control the FBG in engineering according to need by choosing these parameters of the system.
Herein we report aself-powered multimodal temperature and force sensor based on the reverse electrowetting effect and the thermogalvanic effect in al iquid droplet. The deformation of the droplet and the temperature difference across the droplet can induce an alternating pulse voltage and adirect voltage,respectively,which is easy to separate/analyze and can be utilized to sense the external force and temperature simultaneously.Inaddition, an integral displaysystem that can derive information from external temperature/force concurrently is constructed. Combined with advantages of excellent sensing properties and as imple structure,t he droplet sensor has promising applications in aw ide range of intelligent electronics.Temperatureand force-sensing networks are of profound importance in satisfying the demand for applications in eskins or artificial intelligence systems. [1][2][3][4][5][6] Thed iversity of demand has inspired sensor devices based on many different mechanisms,i ncluding resistance sensors, [7][8][9] capacitive sensors, [10] piezoelectric sensors, [11][12][13] thermoelectric sensors, [14] and field-effect transistor (FET) devices. [15] In recent years, simultaneous sensing of temperature and force has attracted increasing interests,inm imicking the functionality of human skin. To realize the functionality,most of the designs integrate as eparate temperature and af orce senor by tiling or laminating,w hich in fact detect multiple stimuli by different sensors individually. [16][17][18] Areal multimodal sensor of temperature and force in apixel still remains challenging.T oaddress this challenge,Tien et al. presented an organic FET to extract the two parameters, [19] while Zhang et al. proposed ac ompressible organic thermoelectric material to realize the functionality. [20] However,b oth the devices may face problems of sophistication in fabrication or post signal processing, since they involve nanoscale fabrication or micro current/ voltage signals.H ence an ew sensing approach with high accuracy and simple architecture is still highly desirable.Herein we report am ultimodal temperature and force sensor using only al iquid droplet of K 3 [Fe(CN) 6 ]/K 4 [Fe-(CN) 6 ]s olution. Owing to the reverse electrowetting phenomenon [21][22][23] of the droplet on the solid surface and the thermogalvanic effect [24][25][26] of the solution, the deformation of the droplet shape and the temperature difference across the droplet can induce an alternating pulse voltage and ad irect voltage,r espectively,w hich can be utilized to sense the external force and temperature.T he interference effect of temperature and force on the integrated voltage signal is also analyzed, so as to distinguish and derive the temperature and force stimuli separately.B ased on these properties,a n integrated sensing and lighting system is also demonstrated.These results may open an ew and cost-effective sensing approach for artificial intelligence systems. Figure 1a schematically illustrates the structure of the droplet sensor,w hich consis...
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