Artificial muscle from fishing line and sewing thread - Page 1
Forum section: electronics / general

author: AlfBaz
author_rank: Super Contributor
timestamp: February 21, 2014, 05:10:12 am
content: This looks promising and maybe even doable at home!http://www.abc.net.au/science/articles/2014/02/20/3948996.htm

author: AntiProtonBoy
author_rank: Frequent Contributor
timestamp: February 22, 2014, 05:54:57 am
content: very coolactual video here:

author: Rerouter
author_rank: Super Contributor
timestamp: February 22, 2014, 06:06:00 am
content: Interesting, but i'd much prefer to see it when you decrease the thickness of the fishing line i'd bet it would react faster and move a greater distance

author: AntiProtonBoy
author_rank: Frequent Contributor
timestamp: February 22, 2014, 06:29:45 am
content: I'm almost tempted to experiment with this myself.*pops open tackle box*

author: AlfBaz
author_rank: Super Contributor
timestamp: February 22, 2014, 10:44:14 pm
content: Quote from: Rerouter on February 22, 2014, 06:06:00 amOther ideas pop into mind. Minimising the distance moved and assuming that "relaxed" the fibre is flexible and "tense" it is to some degree more rigid then some form of construction with these fibres may yield an electrically activated "memory cloth"

author: Rory
author_rank: Frequent Contributor
timestamp: February 23, 2014, 01:47:43 am
content: Does anyone else remember nitinol muscle wire? Same claims were made 7-8 years ago or more - "stronger by far than meat muscles", and you can even buy some at Jameco.https://www.jameco.com/Jameco/workshop/ProductNews/musclewire.htmlDid anything useful ever come out of it?Just wondering you you would control the individual fibers with precision. Maybe form the filament spiral around lubricated heater wire, long enough to allow for expansion?Really I don't see a lot of practicality of temperature-controlled muscle, outside of applications that use the thermal effects as part of the control system input. Didn't see whether the effect is related to tension vs absolute temperature or relative from the temperature at the time the material is placed in a permanently stressed mode.

author: Zero999
author_rank: Super Contributor
timestamp: February 23, 2014, 11:44:38 am
content: It don't see how this could be useful outside of small scale/precision applications because the efficiency will be poor. It's ultimately a heat engine so the thermodynamic efficiency is limited by the hot/cold side differential which will be low at low temperatures.

author: BBQ
author_rank: Regular Contributor
timestamp: February 23, 2014, 12:39:45 pm
content: Perhaps it can be used in pumps?

author: AlfBaz
author_rank: Super Contributor
timestamp: February 23, 2014, 01:23:28 pm
content: Quote from: Hero999 on February 23, 2014, 11:44:38 amI'm confused, wouldn't the differential be low at high temperatures?

author: Zero999
author_rank: Super Contributor
timestamp: February 23, 2014, 02:00:26 pm
content: Perhaps I didn't word that very well.What ambient temperature is it designed to work in?What temperature is it heated to?Unless it's cooled a lot or heated to a very high temperature, the efficiency will be very poor.Suppose the ambient temperature is 22oC (Tc= 295oK) and it's heated to a maximum temperature of 150oC (Th= 445oK)nMAX= 1 - Tc/Th= 1 - 150/445 = 33.7%That's much worse than an electric motor.

author: AlfBaz
author_rank: Super Contributor
timestamp: February 23, 2014, 02:35:31 pm
content: Clearly I'm not seeing something obvious here.You seem to be saying that if it needs to be heated to say, lets go to extremes here, 1000C and cooled down to 0C it's more efficient than if I only need to heat it to 40C and cool it to 20C?I imagine the heated temp would be much less than 150... It's fishing line

author: AlfBaz
author_rank: Super Contributor
timestamp: February 23, 2014, 02:39:58 pm
content: I'm not a paying customer so I don't have access to the Science Journal article but the abstract say's "Highly efficient"http://www.sciencemag.org/content/343/6173/868

author: SeanB
author_rank: Super Contributor
timestamp: February 23, 2014, 03:39:24 pm
content: I would guess they mean it is a lot more efficient than a motor and gearbox. Insulate the line, or select it so it gives the required change without needing external power, and it does the needed job with little lost energy in converting power to motion. If it works without needing power then it will be a lot more efficient than any other method. As it probably only heats up about 30-50C above ambient the required heat is quite low. The motor will probably get as hot with wasted energy as the line.

author: Kryoclasm
author_rank: Regular Contributor
timestamp: February 23, 2014, 05:58:28 pm
content: Funny side note on this, I used to do this twist trick with rubber bands when I was a kid in school for very nefarious reasons...Get the rubber band in a coil the same way they did with the fishing line;I just used my finger and a pencil... then, remove pencil, pull it taught and place in someones hair and let go!The only way to get it out is to cut the hair.Try it at home!

author: Zero999
author_rank: Super Contributor
timestamp: February 23, 2014, 06:08:11 pm
content: Insulating it will not help. If it converts heat to mechanical energy, then it's bound by the second law of thermodynamics, Carnot's theorum, which states that no heat engine can be more efficient than Carnot's theoretically ideal heat engine.http://en.wikipedia.org/wiki/Carnot_theorem_%28thermodynamics%29

author: SeanB
author_rank: Super Contributor
timestamp: February 23, 2014, 06:14:06 pm
content: True, but here we are talking about low torque, slow motion and basically automating something a human can operate with a single finger force. So any motor or solenoid will use more power.