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Using MEMS to Miniaturize Mobile Phones
securitas writes: "The NY Times has a feature on using microelectro-mechanical systems (MEMS) in cell phones to replace bulky passive components like the filters, resonators and duplexers that make up most of the size of today's phones. In theory, they say, you could have a cell phone in a ring on your finger. Besides making everyone seem like James Bond, a ring-phone would give new meaning to the phrase 'Talk to the hand.'"
So now we're going to have a bunch of yuppies talking to their fingers while they drive.
Does this mean people are going to get pulled over for talking on their cell (in areas where it's illegal), when all they were really doing was picking their nose?
What an injustice... what a travisty....
Wow! This must be a PERSONAL letter, just for me!
Even with electronics that use a fraction of what today's phones use, to reduce the size of the phone will reduce the size of the battery you can carry with it. A ring phone can't feasibly hold more than a watch battery.
-Restil
Play with my webcams and lights here
Actually, One ring says I'm committed to my wife. The other Ring shows my commitment to technology!
"Draco dormiens nunquam titillandus."
As several people have noted, you still have a problem with battery size. Also, you have a minimum size for the speaker and microphone to produce a usable signal (the only reason in-the-ear headsets can be THAT small is because they ARE in your ear - to be heard from an inch away from your ear they need be bigger).
And was that guy in the other car flipping you the bird, or just extending his antenna?
I am working in the MEMs area these days. So here are some shameless plugs.
...)
Here
is an general interest article from the group in which I work with some details oriented towards these types of mesoscopic MEMs.
Here
is a neat picture of a Mesoscopic MEMs device (an acceleratometer resting on top the middle part of the "8" in a 1998 penny.
And though my research at Berkeley wasn't MEMS oriented, Berkeley MEMS is pretty active. Here is a link to that.
As the article points out, MEMS are finding applications in cell phones because it is easy to make very small RF filters using inertial effects to provide inductive-like impedences. (In the past, the inductive like parts of a cell-phone filter would either be done with spiral inductors, which are unwieldly or via other microwave circuit voodoo.)
However, beyond cell phones is a grab bag of MEMs applications already at or beyond the prototype stage:
- Car air bag detectors (the above accelerometer)
- Laser gyroscopes
- Projection displays (pixel mirrors arrays)
- Optical fiber switches
- Medical applications (microfluidics, bio-chips,
- Remote sensing (minaturized microphones, or in the future, smart dust)
Enjoy
Kevin
The last guy to go is one of those crypto dudes who wears all black. He holds out his hand and taps his palm a few times. Then after a brief pause he starts speaking to someone as if on the phone, which it turned out he was, this dude had a cell phone implanted into his palm and skull!
Anyway we continued drinking for some time (it was IETF after all) and the dude asked us to watch his laptop for a while while he went to the little boys room. We had some more drinks and were about to leave when someone pointed out that the dude had not returned yet. So I went off to the bathroom to find him.
I find the dude bent over the can with his legs stretched out and a bog roll stuck up his ass. Immediately I think the dude has been mugged. "Hey whats up, you OK?" I ask. "No I'm fine", the dude replies "I'm just waiting for a fax".
Looking for an Information Security student project suggestion?
Try http://dotcrimeManifesto.com/
Smaller parts mean smaller battery, for the most part - except when you have to moving parts like MEMS does.
I doubt that a slower, more expensive and more highly breakable technology is going to be replacing the current one. A general rule of thumb is that no moving parts can be faster/safer/lower power/smaller than moving parts. MEMS has previously been used to replace larger mechanical systems. Its especially good for increasing the resolution of mechanical scans. There was a presentation at my school on the subject - a guy came in with a credit card sized thing and showed that all you do is connect it to a solution and siphon the solution through the card. A MEMS system could then recognize certain chemical agents in the solution (something that is only possible by having a higher resolution scan of the materials).
But for wireless? At least, it becomes extremely difficult to transmit a signal without a large antennae, and I think mems would require more power than passive systems.
This is all the truth of the technology as I have read about it in the past. Has anyone seen anything that contradicts my assertions?
Mod me down and I will become more powerful than you can possibly imagine!
Even if the implementation takes 3-5 years, further reducing the size of cell phones may only be beneficial in a few markets. Most certainly, the US market will not need super small cell phones in the comming years. The Asian and EU markets already sell phones that on average are significantly smaller than those sold in most of the US market. Yes, those are GSM phones, but if the American consumers wanted smaller phones, the manufacturers would quickly swap out the GSM circuits in put CDMA in place. Unfortunatly (for some of us) the average American still tends to like their products to be larger (at least acording to many market research companies.)
Where this technology might be more appropriate is in the imbedded markets. For the Auto-makers, the size of On-Star style equipment could be greatly reduced and in-dash cell phones could have a much nicer and simpler integration.
Though its quite cool to see electornics reaching the miniature level, at some point (which we may have already reached) it will be impracticle to reduce the package size of many consumer electronics. Do you really want a 1 cubic inch sized cell phone that you loose once a week and spend $200 to replace?
As for MEMS, the medical applications are much more interesting.
For people like me who had no idea what coltan is, see this article. The short version is that columbite-tantalite (coltan) is an ore than can be refined into tantalum, which apparently is a very good dielectric for making capacitors. This means that it's not just in cell phones but probably in every electronic device you own.
The controversy over coltan and the Congo seems to revolve around two issues. One is that Congo's neighbors seem to be exploiting its coltan resources, i.e. smuggling coltan and exporting it as their own product. Another is the environmental impact, since illegal mining operations probably care as much about the environmental impact they have as they do about the law.
All of this so far is off-topic, but if rf MEMs could replace capacitive filters and resonators, it could help reduce the demand for coltan. This feeble attempt to be on-topic is purely speculative, though, as I am not a wireless engineer and the NYT article lacks details about the materials being used in these devices.
"It take 9 months to bear a child, no matter how many women you assign to the job."
What is Coltan
Coltan killing elephants, gorillas and people
The Coltan Rush
Minerals Fueling War
Guns, money and cell phones
.
Great strides were made for crazy people when cell phone users started walking around with headsets appearing to talk to themselves. Now it will be even more difficult to tell the difference between technophiles and crazy people!
Although a ring-sized phone will be a practical impossibility, it can be used in a more practical way if it is combined with something else.
The current "best" PDA-phone combination is arguably the Nokia 9210 (or yet-to-be-released 9290 in the US). Although the size is perfectly ok for myself, the weight is not. A ring-sized phone embedded inside a PDA could be the planned direction for this miniaturization.
Palm is too bulky a unit to be used as a phone, contrary to whatever Handspring say about its Treo. The 9210 is too heavy and too thick for most people. Imagine a phone with Palm functionality, the integration of 9210, and the weight of 80g. This ring-phone technology could be the answer to our prayers.
All of this so far is off-topic, but if rf MEMs could replace capacitive filters and resonators, it could help reduce the demand for coltan. This feeble attempt to be on-topic is purely speculative, though, as I am not a wireless engineer and the NYT article lacks details about the materials being used in these devices.
Tantalum tends to be used in low frequency and power circuits. Quite honestly, if you didn't need a mobile phone the size of a domino, you could make them a bit bigger and use plain ordinary electrolytic capacitors instead.
Of course, they use other nasty chemicals, so you just can't win...
The reason US phones are larger is because a smaller phone won't work. The lower US population density means a more sparse cellular network, which means a longer (on average) radio link, which requires more RF power. Better frequency filtering can help some, but there is a fundamental limit (described by the Shannon-Hartley theorem) to how low the power can go. The main reason phones have gotten smaller in the last 5 years is because continued build-out has made the networks denser.
Simply put, a ring-size phone is just plain impossible with anything remotely resembling current physical plant and battery technology.
Who would wanna cell phone in their ring? Keep it in your shoe like any professional spy.
-
ping -f 255.255.255.255 # if only
Motorola already has a cellphone watch. It's worthless as it's battery life is about 30 seconds. outside of digital land (which makes up 75% of the continental US and 90% of Canada.)
They can make it the size of an eraser head, If they cant get me a battery for it that lasts as long as a full day of use then it's worthless technology.
Do not look at laser with remaining good eye.
There's a reason why phones overseas (in Japan and Korea, for example) are so much smaller than they are here. Besides the technology being a small jump ahead over there, Americans seem to have issues with small cell phones-- we think that because they're small, they aren't picking up our voices or that they're toys that somehow don't work as well. And we do this with larger cellphones too (albeit to a lesser degree), probably because we grew up thinking that cellphones were really staticky. Consequently, Americans tend to yell unnecessarily into cell phones, especially small ones. We seem to be uncomfortable accepting the fact that if the microphone part of the handset isn't right next to our mouth, it can still pick up our voice.
For this reason, phone manufacturers actually increase the size of cell phones for sale in America, or otherwise simply choose not to sell the smaller models here. I predict these types of "ring phones" and what-not will probably have a very hard time gaining a mainstream foothold in North America.
Intercarve Networks, LLC
I doubt that a slower, more expensive and more highly breakable technology is going to bereplacing the current one. A general rule of thumb is that no moving parts can be faster/safer/lower power/smaller than moving parts.
I think you're confused about what the "moving parts" are and what they do. Those rules apply to moving parts that rub against each other. These devices are resonators and diplexers, implemented as parts that vibrate and flex, like a bell ringing or a tuning fork humming.
Matter flexes all the time, regardless of whether the motion is deliberate or just a response to heat. Unless the flexing is so large that atoms are displaced from their resting place they don't wear out for geological time.
(Even some displacement is possible without wear. It's called "annealing". Atoms move around slightly to release stresses, resulting in a part the same shape but less brittle.)
For a resonator: In place of electronic tuned circuits (capacitors and inductors, with the action taking place in the motion of electrons and the electric fields between, and magnetic fields around, large conductive structures) you use nanoscopic tuning forks or other shapes with sudden discontinuities.
The motion of electrons through long circuits at about 2/3 the speed of light is repaced by the motion of atoms through distances comparable to their own diameter, at speeds more typical of large masses pushed by moderate forces.
The electric field between two metal plates is miniaturized as the electric fields between pairs of atoms.
The "inertia" of the magnetic field around a long conductor is replaced by the physical inertia of moving atomic nuclei.
The operating speed is EXACTLY the same, as is the amount of energy used. (For a given "Q" factor the friction losses are the same, whether a tuned circuit is implemented as an electrical or nanomechanical structure.)
This kind of thing has been done before - about the time transistor radios became pocket-sized. One example is a miniature quartz crystal about the size of a large ant, precision cut and with precision-deposited electrodes and "doping" weights, replacing (and doing a better job than) about a half-dozen tuned circuits, each pair about the size of a pencil eraser.
But that was for a frequency under half a megahertz. Now we're talking several factors of ten faster - which translates to several factors of ten smaller. And we're now in the range where we can replace several tuned circuits the size of the chip with several silicon and metal structures each about the size of a large transistor.
As for "expensive" to construct, we're not talking microscopic robot arms mounting tiny levers and wheels on axles. We're talking etching a shape into silicon, glass, or conductive metal. This can be done using the same processes that put the circuitry and interconnections onto the chip. (It might not even take any extra steps.)
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