Safer Beach Days with the Sun-A-Wear UV Tracker

Show Notes

Sam from sun-a-wear talks prototyping and validating the new Sun-A-Wear UV Tracker.

Get your own at sun-a-wear.us (US)⁠ or sun-a-wear.com (EU)

My 3 Takeaways

• Good engineering follows the rules. Great engineering knows the rules well enough to bend them.
• Think about specifically how your customer will use this device when making design decisions.
• Use off-the-shelf parts to validate your idea before going to custom designs.

Chapters

00:00 Introduction and Overview

00:24 The SunAware UV Tracker

01:16 The Importance of UV Radiation

01:38 Motivation for Building the SunAware UV Tracker

05:09 Prototyping the SunAware UV Tracker

08:31 Trade-offs in Prototyping

09:01 The Value of Rapid PCB Prototyping

09:53 The Challenge of Battery Charging

10:38 Innovative Solar Power Solution

11:44 Exploring Specialized Components

12:33 Making Design Decisions

13:48 The Importance of Thinking Outside the Box

14:17 The Engineer's Journey

15:28 The Challenge of Firmware Updates

17:03 Future Plans for Over-the-Air Updates

17:51 Exploring Solid-State Batteries

18:52 Advantages of Solid-State Batteries

20:33 Building a Support System in the Hardware Ecosystem

23:25 Embracing the Strengths of a Small Company

24:01 Considerations for Design and Manufacturing

26:20 The Importance of Part Availability

27:19 Hidden Synergies in Component Selection

30:07 The Fun of Engineering and Deep Diving into Design

30:29 Where to Follow Sun-A-Ware

Full Transcript

Vigs (00:00) All right, we're live. I've got Sam here with me from sun-a-wear Sam, thanks so much for joining the podcast, and I'm excited to talk with you about the hardware you're building. Sam (00:10) Hi, thanks for having me. Vigs (00:12) So why don't you start off just giving a brief introduction about what you're building? Because I think it's a very cool application that solves a very real problem. So I want the audience to hear it in your own words. Sam (00:24) Yeah, basically what we're building and currently also selling is our first product. This thing here, we call it the sun-a-wear UV Tracker. And what it is, is it basically measures the invisible ultraviolet light in the sunlight and tells your phone what it measures. And then your phone can help you to deal with UV in a healthier manner. And why that is important is that UV is just responsible for quite a few negative health effects. So most people will know sunburn, but also skin cancer, even different types of skin cancer are caused by UV radiation. Skin aging is mostly also caused by UV radiation. And on the other hand, it also has positive effects. only able to synthesize vitamin D if it gets UV radiation. So we are dealing with the underlying problem that humans don't have any sense for how much UV they get, but it's so relevant for their health. And we decided to attack that problem and build a wearable to help with that. Vigs (01:38) Yeah, and I think it's something that is going to have broad application all around the world because this is a universal problem to us as humans. So very cool that you dove into this. What kind of interests you about the U of E space? Tell us a little bit about what started you with this idea. Sam (01:55) Um, so for me personally, it was mostly a challenge. Um, so I have a background as an electrical engineer with, uh, some dabbling in software, machine learning, but also just building all types of small hardware prototypes. And basically from, from the thing when during my PhD, um, I was approached by a student who had that idea and said like, can I build that? And I thought, yeah, that sounds interesting. So he started building it at first prototype and we quickly saw that A, it's possible and B, yeah, there's actually demand there. So when we talked to dermatologist first, he said, yeah, we've been waiting for such a device for a long time. Can you build more of those? And we said, sure. Yeah, we can. So that's basically the challenge. Like, can we do it? But then of course, from that stage of having something that works to actually getting to a product that is useful, economic, and that people actually want is still a huge step. Vigs (03:03) Yeah, I bet. And just to give you an idea as well, the products that are existing right now, so they have these stickers that you can put on your skin that are going to change colors with UV exposure. Very basic and not technologically advanced, right? So I think that's why it's cool that you're using technology to solve this problem where there hasn't been a smart solution. Sam (03:26) Yeah, yeah. And I think it's just, it's just very natural because the sticker will also be passive and, uh, another product, for example, that I love from a technological perspective, just what they have done with it and how they did it was the, um, L 'Oreal UV sensor. So it's a really tiny, uh, sensor that actually measures UV and records it. And it can even transmit it to your phone, but only over NFC. So. That basically means that you just have to take your phone and actually scan your sensor to know what your UV exposure is. And I think similar to these patches, the main underlying problem is that the sensor cannot warn you by itself. Because the thing with UV is that there are many situations where you are not aware that how strong the sun is and or how quickly you actually accumulate your UV dose and that you would actually reach a level where you're close to a sunburn or just an amount of skin damage that you're not willing to take. And therefore, whatever you're using should be able to get your attention and tell you, by the way, it's a really strong UV situation. Don't you want to do something about it? And that's why we thought, okay, we need to have something that is actually able to A, B, proact. So get the attention of the user, but then also offer a little bit more information than just, for example, this color value that you get on that type. You want it to be like personalized to your skin type or do your preference or even like take into account if you actually applied sunscreen or not. So that's where you need an app and some data processing. Vigs (05:09) Yeah, absolutely. And that's why you guys have the BLA connection to the phone and you use notifications there. Cool. So let's talk about that first prototype that you said you developed. In the hardware world, when you're prototyping, you always want to figure out what is the bare minimum, like an MVP, that I can just put together to see if it works, if it's viable. What did that look like and how is it different than today? Sam (05:33) Yeah. So it took a little bit of learning for me also to actually figure out what, how to prototype stuff. So what, what are the corners that it makes sense to cut and where, where do you actually want to already be kind of closer to the actual product that you want to build? And the, what we went for is just something that used an existing, um, kind of BLE module. Vigs (06:00) you Sam (06:02) So already certified and everything, just a few pins that you can solder to a board and a battery charge circuit that we added and some lithium ion battery and 3D printed housings. And then you could just clip it to your clothing. So that is actually a pretty fast process. But of course, it's still a very long way then to get your product because honestly, like these modules are great. They really allow you to... prototype something really quickly, you even have like a big part of the certification process is taken care of because you, in most cases, you don't have to do additional or F -test or you can actually skip a few. But still it only makes sense up to a certain number of manufacturer pieces because they're more expensive and usually also they are bigger than what you can achieve because oftentimes you can actually leave out a few things or. packet denser or so, depending on your application. And in addition, you also then rely on that manufacturer of that module. So it's one more step in between. So that was just a thing that, um, but if, if I prototype something now, I just, uh, take an existing PCB and rely on a processor that we're already using, just throw new components on there. So I don't. worry about the size, I just add things there, but I'm already using S and D components there and custom design because basically just ordering a new PCP from JLCPCB or whatever, I don't want to advertise anybody or PCP way or whatever, will just take a few days and then you have your prototype. So it's a really cool way to actually get to these things. And then it's just always that trade off like. of like, how close do you actually want to be to your final product? So you can already evaluate the energy consumption, for example, of your device. How long can we get? You can already start developing the firmware for the things if you're using the final components. So that's where you actually want to be close. On the other hand, if you then are doing hand soldering and you have to do it with like, BGA components or so, or the really tiny resistors. Like, yeah, you'll have to find that. Vigs (08:31) Yeah. Yeah, that trade off is important. And I think there's some argument, right? Cause when you're trying to do that initial prototype, um, on the one hand, you might say that the way it looks doesn't matter. It can be big, it can be bulky. And like, you know, other prototypes that I've created in the past just uses a full Arduino board for no reason. Uh, like it's a lot of overkill, but you're getting the minimum functionality out. Um, and I think your point of like the new PCB services nowadays where you get stuff within like a week turnaround time. It helps even speed up prototyping. Sam (09:04) Yeah. Yeah, totally. And for example, you can, you can have the steps of first you make something that works. Just that can be really quick and dirty. Just something with these components that works. Don't worry about the size. That will take you 10 days. You can test it. Fine. And then you shrink the board and order the small version that you can actually show around. So it again, like 10 days and then you have it. So I think like for the. Vigs (09:26) Exactly. Yeah, that's cool. Sam (09:31) absolute first prototype, it makes sense to have something where you have enough test points and you can actually just replace some components or bridge something or so. So you'll probably have some mistakes on there. So it doesn't even make sense to try to make it as small as possible in the first attempt, but usually the second one, you can already go small. Vigs (09:53) Yeah, agreed. And then I think an interesting challenge that you were telling me you had solved was, you know, the initial prototype had the battery charge circuit, you had a battery, and tell me about that journey, because that was something that I found super interesting. Sam (10:08) Yeah, yeah. We actually did some focus group user studies in the beginning and we quickly learned that people don't want to charge an additional device. They already have to charge their phone daily. They have to charge their smartwatch once every day or once every two days or so. They really don't want to charge another device that they rarely use or don't have to think about that often. So we quickly determined that we have a big advantage and that is that. UE radiation only exists outside during the day. So only if you have sunlight. So basically we thought, okay, we should be able to make our device solar powered. The question is just how big does the solar cell have to be? We don't need to have a backup battery because basically if there is no sun, our device doesn't have to work. So we started evaluating and that and playing around with prototypes. And basically we ended up with this thing here. So you can see the The black part in front is just the solar cell. And there's a Bluetooth antenna on the right side and just all the digital components in the back. And this is complete. So what you see there is that there is no battery on there. And all we have on there is a supercap. And that's actually enough for it to, as soon as you go out in the sun, it wakes up, it starts measuring UV, and then it just starts broadcasting these measurements over Bluetooth low energy. And that was also a very conscious trade -off. Yeah. Vigs (11:40) Yeah, that's so. Yeah, just such an innovative solution, like thinking about exactly when and where your product is being used and kind of, you know, bending the rules a little bit of product design and saying, you know, we have these set of strict rules only in the sunlight, only matters outside, and then use that to make a design decision. And would you say that... Go ahead. Sam (12:03) Yeah, that's actually something that I think that's, that's one way of thinking that I feel makes sense to apply in a lot of stages or in a lot of parts of your product. What niche are we occupying and what application do we have? And are there shortcuts we can take due to our special case? And another example would be, I mean, that gets into a lot of details, but for example, we had. I square C pull up resistors and you know, like there's these requirements. Okay. You need a 10 K Ohm for that speed or 4 .7 kilo ohm for that speed or so. But really. If then, if you have a processor that has to do busy waiting while the transmission is going on with the peripheral device, then of course you want that communication to be as fast as possible, right? Because basically your main MCU is just using energy the whole time. Vigs (12:33) you Sam (13:02) But if your MCU has a very nice low -energy implementation for I2C, where it's just sleeping most of the time, you don't really care about the I2C speed. So you can lower the speed, and that means you can actually have higher resistance I2C pull -up resistors. And that also there, you can even start looking at the signal and say, OK, because some peripheral devices will also be able to slow down. If it's. Vigs (13:03) Hmm. Sam (13:32) if it's slower or so. So you can actually figure out if there's, um, if how, what's the fastest speed for us. And it's not necessarily one or the other stream. So you can really fight, find it out really depending on your, your use case. Vigs (13:48) Yeah, I think that's such a cool example of in my mind what's like an engineer's journey through their career. When they first start out, you're like doing stuff by the book, you're just following the reference design, you're looking at other examples. And then once you have a mastery on that, then when you start making something, you can start making these trade -offs knowing the basics very well, and then knowing, hey, I'm changing a rule, a fundamental rule here, but it's okay because it applies to my product this way. So I think that's something... Sam (14:12) Thank you. Vigs (14:17) If an engineer is listening to this, looking to level up, that's something to go from just a regular engineer to someone that can think about the higher level product and the full system as a whole. Sam (14:29) Yeah, yeah, totally. And on the other side, there's also the thing that, yeah, probably divert from the rule sometimes, but sometimes it also makes sense to really dive into them and just read the specs and data sheets in a lot of detail because sometimes they will also actually, you will find things or just edge cases or so where you say, okay, I can actually turn that off or I can make use of that special feature and that will save energy, make it faster, whatever your goal is there. And for us, this was really the thing with, um, when we realized that we don't have to keep a Bluetooth connection between the sensor and the device. There is a special field in Bluetooth advertising called, uh, manufacturer specific data where we can pack a few bytes of information in there and just send it out through the advertisement. So we don't have to keep up that connection. And that's again, when you come back to trade -offs. So we said, okay. basically we would make a device that is due to energy constraints incapable of actually maintaining a Bluetooth connection, which means that we will never be able to serve over -the -air updates, for example. And that's scary. So that was something that was discussed a lot. Basically, if we want to keep a connection, then we have to include a bigger cell. We have to have the whole energy storage solution has to be different. So ... Yeah, you have to be certain about your firmware that it's just good enough. This will work for what we want to do. And we had to learn the hard way that this was a very bold decision for us to make. Because basically, if you look at the device, it's two components. It's the white top part and the black bottom part. We laser weld them together. So once the electronics are in there, the only way to get the electronics out again is actually destroying the device. So we flash the firmware on there. Vigs (16:23) you Sam (16:27) We welded in 1 ,000 devices. And then we discovered a firmware, firmware bug that was actually so bad that we say, there's no way we can ship these devices like that. So we had to go there with exacto knife and screwdrivers and just crack open 1 ,000 devices, reflash the firmware because we decided against over the air firmware updates. So I'll see if I, if I decide to do that again in the future. Vigs (16:51) And then obviously, you know, huge bold decision by you guys. Have you thought about future plans and how can we include OTA on this device? Sam (17:03) Yeah, yeah. So I'm fairly certain that you can, even with that cell size now and with the newer processors that are available now, and also the upcoming SMD solid -state batteries. So you can have something like 100 microamp hour solid -state battery in a form factor of four times three millimeters or something. Vigs (17:29) you Sam (17:33) So really small, you can certainly fit it somewhere on your board. And that will actually be enough to maintain a connection and to write Flash easily. So you can certainly have firmware updates with that. You still need to charge it, and that's a whole other challenge, but it's certainly possible. Vigs (17:51) And what's the advantage of using a solid -state battery? Because I know you've got some samples and you're trying it out. Sam (17:57) Basically higher capacity. So with the, it has not similar size, but yeah, it's the same order of magnitude size on our board as the supercap that we were using previously, but just way higher energy density. And that just allows you to do different things. On the other hand, of course, solid -state batteries aren't as easy to charge because Vigs (18:05) you Sam (18:25) and discharge. So you need some kind of, you need a minimum charge current for. Vigs (18:25) Hmm. Sam (18:32) They have a higher internal resistance. And it's just, as always, it's a trade off again. But if you think about it, 100 microamp hours, that will get you pretty far if you consider the low energy states of the NRF52 family, for example. Vigs (18:40) you Yeah, yeah, exactly. And that's a good point. So what chipset are you currently using? Are you using a Nordic chipset? Sam (18:57) I think I just lost you for the last 20 seconds. So could you repeat? Vigs (19:13) Norris? Yeah, I was just asking what chipset are you currently using? Are you using the Nordic chipset? Sam (19:17) Yeah, yeah, nrf52820 is on the product that is out there and I'm currently playing around with the nrf52810 and 805 just because of the bja package and slightly cheaper. I mean it's just a nice product family and just the tools that you have available. Vigs (19:23) you Yeah. The PPK. Sam (19:44) And by the way, for everybody that wants to develop low energy and hydraulics, it took me way too long to discover the... from Nordic or Power Profiler Kit, which is really it allows you to measure from a few hundred nanoamps up to a few hundred milliamps, everything, and you can record it and you can actually debug it. So a really helpful tool to really inspect your system and optimize it. Vigs (20:05) Agreed. And we've been using it at our company for the past year or so. And it's so accessible, right? Like it's not a super high cost like an oscilloscope or some power supply. It's literally just a small demo kit you plug into your laptop. So cool. One thing I wanted to talk to you about, you know, as a small company, You mentioned a little bit about other startups helping each other. I think the solar cell that you got is also from another startup. The solid -state batteries are also potentially coming from a startup. So talk to me about that ecosystem when you're building hardware. How is it to have that support system around you? Sam (20:51) Yeah, I think it's just a win -win situation for a product that builds electronics and to work with up and coming hardware providers or new technologies because oftentimes for them, they still have to figure out their processes. So they cannot start with manufacturing millions of pieces for a big customers. They probably also don't want to have the Vigs (21:06) you Sam (21:20) exposure of directly selling a huge number of their parts to a huge company. So they are actually happy to work with you as a smaller customers and just have a direct personal interaction. You can give them early feedback on their technology and they can provide it to you and actually get this important feedback. And for us, for example, yeah, one thing we're using are these Perovskite solar cells. So they have a much higher efficiency indoors. And the important part also about it there is that the guy that does it, so they're called Kirovska Solar, the company that does it, and they are inkjet printing these cells. So basically we can tell them we would like to have a cell that has exactly that shape and size, and they will make it with very low tooling costs because they are basically printing it. Vigs (21:53) you Sam (22:19) That's so cool. And we've been working with them right from the start. And together, we actually learned how to make the surface area as big as possible and the borders as small as possible. They had to just improve their processes over and over again because, yeah, but these edges, we still lose a lot of space there. And just he went back and came back. Is this better? Does this work better? But it's so cool to do that. And I'm expecting some new prototypes just in the next few weeks with tiny, tiny cells, the smallest they've ever done. So. Vigs (22:47) Wow. Sam (22:49) excited to get my hands on those. Yeah, in general. And yeah, these solid -save batteries are also pretty cool. I just started talking to a guy at the expo who said, yeah, we're doing these new batteries. They will be available beginning of 2024. And I said, can I have samples? And he said, sure. So it's just a nice way to do that. And you can basically, you're already at the disadvantage in with. many respects in comparison to the big companies. So that's at least something where you could probably get ahead a little. Vigs (23:25) Yeah, I really liked that. And the reason I kind of wanted to ask you about that is because I think it's a very good example for others to realize, you know, a lot of people might get intimidated because, oh, you know, I'm not doing millions in quantity every year and I'm not having a high volume. And so it might discourage them from reaching out. But here's the value that you're showing in having a startup making lower volume, interfacing with other startups that are looking to partner specifically with lower volume customers and kind of. Sam (23:42) Thank you. Thank you. Vigs (23:53) everyone helps each other and it grows together. So that's why I think I wanted to highlight that just because you have to embrace your strength. And in this case, your strength is being a small company. So you have to use that to your advantage. Yeah. So one thing that I like to ask, what were some of the things that if you had to start over from the beginning, something that you might do differently from a design perspective or manufacturing perspective? Sam (24:01) Yeah. Absolutely, yeah. So the one thing I had to learn the hard way is look at part availability when you design your product. And that became especially clear once the chip shortage hit in 2020, when all of a sudden all of our processors were just not available. You could buy 100 here, 100 here, but it was just... Vigs (24:44) you Sam (24:51) Previously, they were just available in the tens of thousands or hundreds of thousands all over the place and all of a sudden, nothing. And of course, this was an extreme situation, but it makes sense for all the parts that you are considering, including your design, to just look around in the beginning and say, okay, I was availability. What are the lead times there? How big can we scale this thing before it could actually be an issue? And that was certainly... One learning. Oh, yeah, there's also an anecdote with that and When we had that problem, we actually want to get our hands on some kind of chip from the nrf -52 family So we weren't even set on a specific one, but basically it would have been nice if the footprint matches our current design but otherwise we were we were not that specific on what we wanted but wanted to have a few thousand pieces and Vigs (25:23) Okay. Sam (25:50) It was just not available. And all of a sudden I'm browsing on DigiKey and I see 4 ,000 pieces available. I was unable to find anything in that order of magnitude. And they were even cheap. So previously I was also in contact with some of these scalping companies that just buy up chips and try to resell it to you for X time the price or so. And I just, I really disliked that. So I couldn't believe it when I thought it's 4 ,000 pieces there. hit buy, rejected my payment solution in the beginning, but eventually I got it and a few days later I had 4 ,000 processors at my home. So that was really cool. And then we had to figure out how to actually ship them to China for our contract manufacturer. So that was a whole other story, but it would have been nice if in the beginning we would have looked at the availability of these parts. Similarly, of course, it helps if you... Vigs (26:40) Yeah. Sam (26:49) consider the certification process. So for most products, you'll have to go through some kind of certification in Europe CE, in the US FCC. So that's just something where it helps to have done it, of course, before, but just keep it in mind that this will actually add some time and in the case of the US, probably also some cost in the end that you just have to plan ahead for because it's... Vigs (27:01) you Sam (27:19) These things can just take quite a while. Vigs (27:24) Yeah, agreed. I think that's one thing that, you know, I told you, I work at a design company and we had a period of time where we were looking at designs and we were looking at parts. And before we even started the design, we were asking our customers, our clients to buy all the inventory that they could afford because, you know, we don't want to run into the case of doing a full design, getting to the end, and then not being able to procure any of the bomb parts, right. And having to redo the whole design. So. Sam (27:24) Yes, that's what we think. Vigs (27:52) It was obviously a tough decision to have with clients because no one wants to pay upfront, right? But having that discussion to be like, you have to buy these parts, otherwise we risk the entire schedule. And I think something that everyone in our industry can relate to just in the past couple of years with the shortage. Sam (28:09) Yeah. And probably also something that, yeah, is pretty relevant in the beginning. Like when you start selecting components for your device, oftentimes you just consider like compatibility and see, okay, do we have a similar voltage range that they can use? And then you try to find an energy storage solution for that range and everything. But it makes sense to even have a... deeper look into these components because oftentimes there are hidden synergies that you could use. For example, if you have a solar powered device, you could decide to just use multiple cells and get a higher voltage out of your photovoltaic system. And that means that, for example, if you have a boost converter, if you steal NEMA, then that boost converter could actually run in a more efficient range. if you lose a little bit by having multiple cells on your board and maybe you could even get rid of the boost converter completely and then of course you save a lot and these kind of things or if you look at your storage solution or your processor like what's the lower end of the voltage range maybe you can go really low and that helps in many cases as well to just conserve a lot of energy and just there are many of these hidden synergies between different stages of your system or components that you actually can dive in deep and think, okay, how can we just use abuse these systems? Or if you know that you, for example, you only need a specific components once you will reach the higher voltage and you can just turn that part off of your circuit until you have enough energy or so. These are all things that you probably can consider right from the start and will just help you to make a better point. Vigs (30:07) And in my opinion, that's what makes engineering really fun. You're not just making the same MCU charge circuit over and over. You're actually deep diving and looking at all these individual things for every different product in every industry. Sam (30:21) Yeah, absolutely. Vigs (30:23) Cool. So it's it was an awesome having you Sam Switzerland right now. Where can people go to follow you to stay tuned to the Sun Over journey. Sam (30:35) Um, so basically sun aware .com. So that's S U N hyphen a hyphen W E A R .com or sun aware .us. We are actually now also shipping in the U S we have a shipping service set up there. So, uh, people can try it. People can test it. It can also rip it open and reprogram the N R F chip if you want to do something else with it. So if we could do that, I'd be happy to see some mods out there. Vigs (31:06) You're trying to sell a demo kit now. Cool. Thanks so much, Sam. I appreciate your time and coming on. Sam (31:09) you Thank you very much for that discussion.

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