According to an article by Rob.M. (2020), MIT researchers have found a way to program soft robotic arm to understand its structure in 3D space, using "motion and position data from its own "sensorized skin".
These soft robots are built from highly flexible materials, alike to "those found in living organisms", are supported as "safer, and more adaptable, resilient and bioinspired alternatives to traditional rigid robots". Traditional sensors reduce a soft robot functionality and also complicate its manufacturing process.
The researchers narrate it as a system of soft sensors that wrap over the robot's body, that feedback to the internal AI to provide the robot "awareness of motion and position of its body"
The soft robot's materials have "piezoresistive" properties, this mean when its original shape undergoes any physical changes, its electrical resistance changes with it. The material shape is "inspired by kirigami", with a variations of patterns etched on the rectangular silicone sheets, this changes the elastic of the material. However, I believe that there other sensor such as piezoelectric sensor which is more suitable and superior than piezoresistive sensor.
One of the disadvantage of piezoresistive sensor, is its pressure sensitivity vary under different temperature. Since piezoresistive works by detecting strain in the material, it is important to note that molecules behave differently in certain temperature. Thus, it can only function as it is intended under certain temperature, which greatly limit its uses.
Another disadvantage of piezoresistive sensor, is that external stress that occur during the processes of chip fabrication and packaging, will affect its performance. During passivation process, silicone is coated with silicone dioxide and silicone nitride, the process induces stress to the passivation layer, this could detriment the performance of devices with thin diaphragms.
Overall, the disadvantages of piezoresistive sensors outweighs its benefits, while the advantages of piezoeletric sensors easily make make the device more compatible in varies environments and cost efficiency.
References:
Liu.Y, Wang.H( 2016, Nov 24) Thermal-performance ubstability in piezoresistive sensors: Inducement and improvement.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5190965/
Capacitive vs piezoresistive vs piezoelectric pressure sensors (n.d) Avnet Retrieved 17 February, 2021, from
https://www.avnet.com/wps/portal/abacus/solutions/technologies/sensors/pressure-sensors/core-technologies/capacitive-vs-piezoresistive-vs-piezoelectric/
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