PSIcle sensor: Measure tire pressure with your phone!

Created by Rover Development

Measures your bike's tire pressure with your phone. Spot check pressure before rides, after fixing flats, or fine-tune on the trail.

Latest Updates from Our Project:

Circuit boards complete and threaded extensions
3 months ago – Sat, Apr 16, 2022 at 11:07:23 PM

Hi Everyone.  We've had another month of delays and frustration, but the major milestone since the last update was the completion and receipt of all the circuit boards.  There were numerous delays in both the build and shipping due the entire city of Shenzhen, China being shut down, but we finally received them, and they look and work great.  This is a huge milestone passed on the road to delivery of the units.

We also received some new extensions that we believe may help address the sealing issues.  The new extensions have threads all the way down the body, as shown below.  These threads will provide more surface area for the rubber to adhere to and should improve the sealing.  The last mold trials only had leakage along the smooth body of the original extension, so the zig zag of the threads should help address this.

These extension tubes were also extremely delayed due to the shutdowns in Shenzhen, so we were just able to ship the tubes and circuit boards to the molders this week.  It's a really difficult time to make anything in China with citywide shutdowns affecting numerous different cities.

Due to the delays in receiving the circuit boards and extensions, there have been no new mold trials since last month.  We are working with both molders to define their mold trial schedule for the new molds and will provide an update as soon as we can.  We apologize for all the delays and rest assured, we are just as frustrated as you.  We are pushing forward as hard as we can despite the odds and we are making progress bit by bit.  Thank you for your patience.

Molding and other updates
4 months ago – Sat, Feb 26, 2022 at 10:33:15 PM

Hello everyone.  A lot of activity this month, but we will still be waiting a while to see the ultimate results.

The Taiwan molder was not able to make leak free assemblies before Lunar New Year, so we started talking to the US molder and quickly ran into an issue.  We originally had them quote a higher quantity, so when we went back with the final quantity purchased by the campaign they were not able to make the parts cost effectively.  Essentially, their costs, which were already much higher than the overseas molders, were much higher than expected at lower quantity and we couldn't make the order work.  They did agree to serve as a paid consultant to help us to get good units molded, so we may use their expertise after all.

When Lunar New Year ended, we got into deeper discussions with the molder, and they have requested some modifications that they believe, and we agree, will make the design much easier to seal.  The design changes add about 1 gram of rubber to the overall weight.  This additional weight is not ideal, but shouldn't pose any major issues with bike wheel balance, even at high speeds.  Plus, it's the lowest risk path to getting parts, so we opted to do this, at least for now.  We just paid for this new mold and we should see results in about 4 weeks.  This will still be a prototype mold because it can only make one part at a time, and parts take a long time to make with this molding technique.  To get the unit cost down, a production mold would need to be made afterwards if this mold works.  An image of the revised design is below.

To further reduce risk, we reached out to over a dozen other overseas molders and found one that has promised us a money-back guarantee that they can make the units.   A potential major advantage of their design is that it will inject liquid plastic into the mold.  The previous vendor used solid preforms that get squished when the mold closes.  Although this is a standard way to make tire valves, it has been difficult to get this process to work well with our circuit board.  Closing the mold first and then injecting liquid plastic may be significantly simpler.   Another major advantage is that each mold cycle is faster, so if this first mold works, it will serve as a production mold - there is no need to make a different production mold.  We also expect results in about 4 weeks on this.

If the molds still don't seal, we plan work with one or both vendors to apply epoxy to the units to seal the sensors before they go into the mold.  This is what we've done for all the prototypes and it works really well, but it is very time consuming to apply.  Epoxy would work, but would add a lot of labor so we don't want to have to go to that unless we can't get the molding to work.

The circuit boards are in process and should be done on about March 7th.  At that point, we can send some to the vendors to have on hand when they begin their mold trials.

The apps are ready, though the iOS app won't go up on the app store until we're able to send some hardware to Apple for them to evaluate.  This will happen after we get some good parts off the molds.

In spite of the extra mold costs, we're doing ok with funding and we should be able to fill all the orders with one of the molding methods above.  This has obviously gone on much longer than we originally said, but the learning curve for the molder has been so much longer than we expected, especially given the fact that we had prior experience with them.  Thanks for your patience!

6 month update
6 months ago – Thu, Jan 20, 2022 at 04:01:09 AM

Hello all.  We've had some good progress this month and I think we're basically one minor breakthrough away from manufacturing and shipping.

First, there's been some progress in the molding.  The molder has managed to seal the molding material around the extension and created a leak free seal.  This is a big accomplishment because the leaks around the tube were previously quite bad.

At this point the molder is having some issues in preventing the circuit board from moving during the molding process.  The circuit board moves and breaks through the rubber surface, causing a new leak point.  This type of issue is why we built a prototype mold before a production mold.  We've already discovered several things we will change in the production mold to make the sensors easier to make.  In the meantime, we may just make the rubber material thicker in the area shown in the small picture below to seal any leaks even if the circuit board moves during prototype molding.  It's easier to make material thicker because to do that you remove steel or aluminum from the mold.  Removing mold material is a lot easier than trying to add it back in.  This is often called "steel safe" in the molding industry, and it will allow us to quickly change the design for further leak improvements and tests, if necessary.

This month we managed to find a vendor who was willing to make less than 2000 aluminum extension tubes for testing, and we purchased 100 of them.  They looked great and went straight to the molder in Taiwan for the mold trials described above.  We're ready to order the balance of the units needed after we finalize a molding process.  The lead time on these extension tubes is about two weeks.

We also decided to place the order for all the circuit boards, since we currently feel that it is unlikely that changes will be needed on the circuit board.   All of the components were shipped to China for the circuit board assembly.  The circuit boards should be complete by the end of Feb.  By then, we should know who is molding them and the circuit boards can go into molding.

Which brings us to the last point for the update.  We've given the Taiwan molder until Feb 1st to make leak free assemblies and send them to us.  If they are unable to do it, we will start working with the US-based molder.  This ultimatum seems to have paid off already as they were able to create a seal around the tube where they had not been able to before.  If they keep making progress, we should have the first leak free samples soon.  If not, we'll be starting up with the US-based molder in Feb.  Although they are a lot more expensive, they have more experience and it will be far easier for us to communicate with them and visit their facility.  One way or another we'll get this done.  Your patience is very much appreciated!

Month 5 update
7 months ago – Mon, Dec 13, 2021 at 02:51:19 AM

Hello all!  We've made some good progress this month in a few areas.

You may remember that last month's update discussed how there wasn't enough stock in the whole world of the main integrated circuit (IC) chip used in the originally circuit board.  At first it looked like there was sufficient stock, but when we placed the orders we found that the stock numbers that were shown on the vendor websites were not valid.  We only managed to get 1000 of 1600 ICs we needed.  As mentioned in the last update though, we had a backup design that uses a totally different IC.  So this month, we adopted that new design and procured the different main integrated circuit chip that design uses.  We're happy to say we were able to get all 1600 units of that IC this month and we were able to return the 1000 of the original IC for credit.  We also have all the pressure sensor elements we need on hand.  This means we now have all the circuit components we need to deliver all the sensors!

After we realized we'd need to switch to a backup design, we had to redo the Android and iOS apps, so we did that this month as well.  The iOS app is still not on the Apple store because we need to provide them hardware so that they can test and approve the app.  It's kind of a painful process, but that's what it takes to get into Apple's walled garden.  We'll do that once we have some of the new sensors molded.  

This month we also received 1600 units of a special component that goes between the circuit board and the extension tube.  Since the extension is metal, it will interfere with the NFC transmission unless we put a special material between the extension and circuit board.  We had to order a custom die cut tool and have these spacers die cut for the sensors.  The tool was finished and the vendor cut and shipped 1600 units this month.

The sensor assemblies that have been molded so far leak pretty badly.  The molder also used all the prototype extension tubes we sent them, so we had to order more so they can resume mold testing.  We struggled this month to find a vendor who was willing to make less than 1000 extension tubes in this next order.  This was a problem because we still didn't know if the design was going to need to change to get the molding to seal air tight.  Eventually, after a fair amount of searching, we found a new vendor and were able to place an order for 100 extensions with 900 more to follow after we approve the first ones.  We expect to see those first 100 extensions in the next two weeks.

So that brings us to the molding.  This month we had in-depth conversations with the US-based molder and they are very confident they could mold this design and make it airtight.   This makes them a great backup plan for us.  However, we are going to give the 100 extensions that we have to the original Taiwan-based molder to see if they can make some air tight test units.  If they can't do it after 100 units, we're probably going to have to go with the US-based backup molder, which will cost much more.  If the Taiwan-based molder can't make progress after 130 units, it's unlikely they will ever figure it out. 

The circuit board design is ready to order, but we're holding off until we know a bit more about the molding.  It's possible that we might need a subtle mechanical change to the circuit board for molding, and that could be impossible to do after we have the boards built.  For the mold trials, we've ordered and received blank, unpopulated circuit boards.  These aren't very expensive, but they still allow us to test the mechanical properties of the molding process without using up our valuable components.   These circuit boards are on-hand, so as soon as we get extensions, the boards and extensions will be sent to Taiwan for molding.

So we should know a lot more about how we will achieve an air tight sensor by the next update.  Thanks for your support!

4 month update
8 months ago – Sun, Nov 14, 2021 at 02:58:23 AM

This month we were able to have a small batch of trial sensors molded and the circuit boards survived the molding process.  Proving this out was obviously key to making the sensor work.  We had previously injected molded over the circuit boards with hard plastic, but the rubber process we're using now uses a solid rubber preform in the mold, and it was possible that it would put more pressure on the circuit board and that it could damage it.  This didn't happen to any of the sensors, and they look great:

We also had the vendor test some transfer printing, which you can see on the right side of the picture.  That will allow us to differentiate the LP and HP sensors without needing to have different molds for each.

The big issue now is that the rubber isn't sealing well to the extension.  The leakage we are seeing would not be acceptable for any bike tires.  The vendor thinks, and we agree, that they used rubber that was too soft.  The vendor has needed to do a lot more process development than we expected.  It's possible they could solve the leakage soon, but it's also possible they might never solve it.  It doesn't help that the vendor is in Taiwan, so there can be language and timezone issues.  It's also much harder to visit them. 

We know the leakage has to be solvable because the materials we are using are the same as those used in car tire valves and they form completely air-tight bonds with the brass valve body.  We're talking to a backup vendor now who has more experience with rubber molding, and they are very confident they could make the assembly leak-free without significant changes to the design.  The prototype tool we have now can only mold one sensor at a time, so each sensor takes several minutes to mold.  We knew we were going to need to buy a larger mold to make more sensors at a time, and so we'll need to decide if we are going to buy that through the current vendor or the backup.  The backup vendor is in the US and it would be a lot easier for us to visit them to work out processing kinks.  They're quite a bit more expensive, but it could be worth it to get everything working right.

Next week, we'll be receiving one of the custom die-cut parts that goes inside the sensor that makes the NFC work next to the metal extension tube.  Once we have those, we can place the order for the circuit boards, and those are quoted to take about 8 weeks to come in.  While we're waiting on those, we'll monitor the leakage fix progress with the Taiwan vendor and determine which vendor we'll use for production.

Another issue that we've run into but think we have resolved is the global electronic component shortage.  We have enough components right now to build 1000 sensors, but we have 1600 sensors to build.  We have been unable to source the last 600 components we need to build those sensors - the lead time for the last 600 components is over a year!  However, going into the Kickstarter, we had a few different designs that we knew would work, so we are currently evaluating what it would take to put a backup design into production instead.

The actual lead time for the original part

So we are making progress, but it continues to be much slower than we anticipated.  Last month we said early bird sensors wouldn't ship until December, but now it looks more like January.  We anticipate we'll make all the sensors around the same time, so the later backers will ship around the same time as the early birds ship.  We appreciate your support and patience, and we are eager to get the first sensors in your hands.  Kickstarter has posted a good article summarizing some of the supply issues we're seeing right now.  It's definitely worth a read if you want to understand more about why it's hard to get things built at this point in time.