Who of us has n’t wished for their ownPurple Crayonlike Harold ’s ? While this new graphite - based piezoresistive detector wo n’t make your home come animated with creatures from your imagination , it will provide an cheap , easily - employ means of measuring mechanically skillful stresses . You ’ll just need a pencil and newspaper .
Piezoresistive sensing element ( PZRs ) quantify mechanical accent by measuring a drop in resistance that takes place when the sensor is put under melody — that is , the more force play that ’s utilise , the more the detector ’s electric resistance drop . They ’re commonly used as imperativeness sensors and accelerometers . Typically , PZRs are made of silicon , which get very accurate recital but is relatively expensive to manufacture . Recently , however , a team from Cheng Shiu University in Kaohsiung City , Taiwan , discovered that regular graphite — like , from pencil — can be utilized as well .
These sensors ’ truth are mensurate along thegauge factor(GF ) . Si sensors rate around 100 , while the plumbago sensors assess ways down in the single digits . Surprisingly , the team find that the grad of the pencil lead-in used affected its GF rating . As Physorg point out :
In experimentation , [ lead researcher , Ting - Kuo Kang ] used 12 different grades of graphite pencils to draw U - shaped PZR sensors on paper . The pencil are graded by their proportion of graphite to clay . grade ranged from 9B to 2H , where H refer the harshness triggered by the pencil ’s clay content , and B denote the blackness due to the black lead content .
The detector were drawn on paper that was place on an electric graduated table in guild to measure out and maintain a reproducible drawing force for each pencil - reap detector . The drawings were then glued on printed circuit board ( PCB ) strips , and a strain gauge mounted on each PCB strip . Then Kang applied hertz of stress to the sensor using a four - point bending proficiency , and appraise the sensor ’s voltage change under the applied stress through an electric circumference .
Even so , the plumbago variety cost a fraction of what silicon does to develop . As the engineering science develops , it could very well usher in a raw undulation of low - toll , disposable tension sensors that could be applied to infrastructure like bridge deck and flyover , reporting prepare structural failures before they become dangerous . [ AIPviaPhysorg ]
figure : tfox2000
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