Necrobotics: Difference between revisions

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'''Necrobotics''' is the practice of using [[biotic materials]] (or dead organisms) as robotic components.<ref name="10.1002/advs.202201174">{{Cite journal|title=Necrobotics: Biotic Materials as Ready-to-Use Actuators|date=July 25, 2022|journal=Advanced Science|doi=10.1002/advs.202201174 |last1=Yap |first1=Te Faye |last2=Liu |first2=Zhen |last3=Rajappan |first3=Anoop |last4=Shimokusu |first4=Trevor J. |last5=Preston |first5=Daniel J. |volume=9 |issue=29 |pages=e2201174 |pmid=35875913 |pmc=9561765 |s2cid=251038837 }}</ref> In July 2022, researchers in the [[Preston Innovation Lab]] at [[Rice University]] in [[Houston, Texas]] published a paper in ''[[Advanced Science]]'' introducing the concept and demonstrating its capability by repurposing dead spiders as robotic grippers and applying pressurized air to activate their gripping arms.<ref name="10.1002/advs.202201174"/><ref name="ieee">{{Cite web|url=https://spectrum.ieee.org/robot-bugs|title=Necrobotics: Dead Spiders Reincarnated as Robot Grippers|date=July 26, 2022|website=IEEE Spectrum |first=Evan |last=Ackerman |access-date=July 29, 2022|archive-date=July 29, 2022|archive-url=https://web.archive.org/web/20220729072153/https://spectrum.ieee.org/robot-bugs|url-status=live}}</ref><ref>{{Cite web|url=https://news.rice.edu/news/2022/rice-engineers-get-grip-necrobotic-spiders|title=Rice engineers get a grip with 'necrobotic' spiders|website=Rice News |publisher=Rice University |date=July 25, 2022 |first=Mike |last=Williams |access-date=2022-07-29|archive-date=2022-07-29|archive-url=https://web.archive.org/web/20220729062738/https://news.rice.edu/news/2022/rice-engineers-get-grip-necrobotic-spiders|url-status=live}}</ref><ref>{{cite news |title=Scientists turned dead spiders into robots |url=https://www.sciencenews.org/article/dead-wolf-spiders-robots-necrobots |access-date=21 August 2022 |work=Science News |date=4 August 2022}}</ref><ref>{{Cite web|url=https://www.theverge.com/2022/7/28/23282023/dead-spiders-robot-grippers-necrobotics-research-rice-university|title=Scientists reanimate dead spiders as robot gripping claws|first=James|last=Vincent|date=July 28, 2022|website=The Verge|access-date=July 29, 2022|archive-date=July 29, 2022|archive-url=https://web.archive.org/web/20220729072153/https://www.theverge.com/2022/7/28/23282023/dead-spiders-robot-grippers-necrobotics-research-rice-university|url-status=live}}</ref>

Necrobotics utilizes the spider's organic hydraulic system and their compact legs to create an efficient and simple gripper system. The necrobotic spider gripper is capable of lifting small and light objects, thereby serving as an alternative to complex and costly small mechanical grippers.<ref name=":1">{{Cite web |title=Necrobotics: Dead Spiders Reincarnated as Robot Grippers - IEEE Spectrum |url=https://spectrum.ieee.org/robot-bugs |access-date=2023-10-19 |website=spectrum.ieee.org |language=en}}</ref>.

== Background ==

The main appeal of the spider's body in necrobotics is its compact leg mechanism and use of hydraulic pressure.<ref name=":2">{{Citation |title=Spider anatomy |date=2023-07-20 |url=https://en.wikipedia.org/w/index.php?title=Spider_anatomy&oldid=1166225476 |work=Wikipedia |access-date=2023-10-19 |language=en}}</ref><ref name=":4">{{Cite web |title=Leg Uses Hydraulics and Muscle Flex — Biological Strategy — AskNature |url=https://asknature.org/strategy/leg-uses-hydraulics-and-muscle-flex/ |access-date=2023-11-04 |website=asknature.org |language=en-US}}</ref>. The spider's anatomy utilizes a simple [[Hydraulics|hydraulic]] (fluid) pressure system. Spider legs have flexor muscles that naturally constrict their legs when relaxed.<ref name=":0">{{Cite journal |last=Yap |first=Te Faye |last2=Liu |first2=Zhen |last3=Rajappan |first3=Anoop |last4=Shimokusu |first4=Trevor J. |last5=Preston |first5=Daniel J. |date=October 2022 |title=Necrobotics: Biotic Materials as Ready‐to‐Use Actuators |url=https://onlinelibrary.wiley.com/doi/10.1002/advs.202201174 |journal=Advanced Science |language=en |volume=9 |issue=29 |doi=10.1002/advs.202201174 |issn=2198-3844 |pmc=9561765 |pmid=35875913}}</ref><ref name=":4" />. A force is required to straighten and extend their legs, which spiders accomplish by pumping hemolymph fluid (blood) through their joints as a means of hydraulic pressure.<ref name=":1" /><ref name=":4" />. It takes no external power to curl their legs due to their flexor muscles' natural curled state.<ref name=":0" />.

In July 2022, researchers in the Preston Innovation Lab at Rice University published a paper detailing their experiments with the gripper. Although dead spiders no longer produce hemolymph, Te Faye Yap (lead author and mechanical engineering graduate) found that pumping air through a needle into the spider's [[Spider anatomy|cephalothorax]] accomplishes the same results as hemolymph.<ref name=":0" />. The original hydraulic (fluid) system is essentially converted into a pneumatic (air) system.

== Fabrication ==

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== Testing and Data ==

==== Internal Force Versus Gripping Force<ref name=":0" /> ====

The typical pressure in a resting spider's legs ranges from 4 kPa to 6.1 kPa. Researchers extended the legs by increasing the spider's internal pressure to 5.5 kPa.<ref name=":0" />. Pumping air into the body increases the internal pressure, causing the legs to expand. Pumping air out of the body decreases internal pressure, causing the legs to contract due to their flexor leg muscles. When the internal pressure decreases to 0 kPa, the gripper would be fully closed, allowing for the gripper to grasp objects. This action demonstrates that as internal pressure decreases, the gripping force increases. Inversely, when internal pressure increases, the gripping force decreases.<ref name=":0" />. By gripping individual weighted acetate beads, it is found that the necrobotic gripper achieves a maximum gripping force of 0.35 milinewtons.<ref name=":0" /><ref name=":1" />.

==== Spider Weight Versus Gripping Force<ref name=":0" /> ====

To estimate the gripping forces of smaller and larger spiders, researchers created a plot to predict the gripping force relative to the size of the spider. The wolf spider's body weight is relatively equal to the gripping force of its legs.<ref name=":0" />. The mass of the gripper is 33.5 mg and can lift 1.3 times its body weight (43.6 mg or 0.35 mN).<ref name=":0" />. However, with larger spiders, the gripping force relative to body weight decreases. For example, a 200-gram [[goliath birdeater]] is predicted to lift 10% of its weight (20 grams or 196 mN).<ref name=":0" /><ref name=":1" />. Though there is an inverse relationship between spider mass and gripping force, larger spiders exert greater gripping forces than smaller spiders.

==== Gripper Lifespan<ref name=":0" /> ====

The necrobotic gripper's functionality is entirely reliant on the structural integrity of the spider. If the spider were to break down easily and frequently, the gripper would not be practical. Using cyclic testing, a series of repeated actions, it is found that the necrobotic gripper can actuate 700 to 1000 times.<ref name=":1" />. After 1000 cycles, cracks begin forming on the membrane of the leg joints due to dehydration.<ref name=":0" />. Weakened and decomposing joints lead to frequent breakage and replacement, thereby serving as an obstacle in applying necrobotics to real-world scenarios.

One theorized fix to this issue is applying beeswax or a lubricant to the joints. Researchers found that over 10 days, the mass of an uncoated spider decreased 17 times more than the mass of a spider coated with beeswax.<ref name=":0" />. Lubricating joints combats dehydration and slows the loss of organic material.

== Applications ==

Necrobotics can serve as a fast and precise alternative to mechanical components that are difficult to manufacture. Due to small mechanical grippers being costly and complex, the necrobotic gripper can be used as a replacement. Fabricating these pneumatic spider grippers can be done in under 30 minutes and have a relatively long lifespan of 1000 cycles.<ref name=":0" />. The necrobotic gripper is ideal for processes requiring delicate handling of materials and maneuvering light objects into tight spaces. There may also be applications in [[microelectronics]] where necrobotic grippers can handle simple pickup and dropping actions.

Besides the necrobotic spider gripper, there are no other robotic concepts under the necrobotics subfield. Future necrobotic concepts can utilize soft robotics and electrical stimuli to repurpose biotic material into biohybrid systems. Another application of necrobotics is utilizing preexisting bone structures to house robotic components.

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The main limitations to necrobotics are its durability, maintenance, and questionable morals. With the usage of organic material, there is a higher chance of the component decomposing and breaking down as opposed to traditional mechanical systems. There may be additional work and management required to replace these grippers if they fail. Additionally, organic inconsistencies with the spiders will yield inaccurate results. Not all wolf spiders develop the same, so gripping force and leg contraction can vary between grippers.

There are moral implications behind euthanizing spiders for robotics. The ethical boundaries that necrobotics push in the pursuit of biohybrid systems raise concerns, as opponents say it may lead to the hybridization of mammals and is intrusive to nature.<ref name=":3">{{Cite web |title=How ‘Necrobotics,’ or Using Dead Creatures as Robots, Is Changing Science |url=https://www.theswaddle.com/how-necrobotics-or-using-dead-creatures-as-robots-is-changing-science |access-date=2023-10-31 |website=www.theswaddle.com |language=en}}</ref>. Proponents respond that repurposing dead animals has been human practice for millennia and that necrobotics should be pursued to advance science.<ref name=":3" />.

== See also ==