SummerBlogs

Annie's Summer Blog

My links:

1. My profile
2. Literature review
3. Interview notes

06 August

Hello blog readers! Today I did SO MUCH casting. I started out by solidifying my process for both the GEL shell + solaris fill as well as a reflective coating technique. At first I thought that I could make my entire GEL shell reflective, because then I could just eliminate the coating step. I tried this, and I couldn't see any deformation because the reflective layer was too thick. So, then I went back to my usual process except I formalized my reflective coating process:

1. 1g GEL A
2. 1g GEL B (then mix)
3. 0.2 g Silver Bullet Powder
4. 0.1g dark aluminum powder (then mix and degass)
5. Drip over elastomer placed on aluminum foil to get even coating
6. Cure in toaster oven on dark-toasty
7. Coat with baby powder so it it not sticky
8. Cut away aluminum foil and excess coating drip with scissors, being careful not to alter the bottom of the elastomer (we want that crystal clear)

I eliminated NOVOCS Matte because I do not think it helped with the dulling of the surface, and it made the mixture too thin so my reflective coating would easily tear off. This reflective coating ended up pretty good, and I will show some pics of results in my blog post tomorrow.

I also made my phantoms for my test set up. Using the same mold as before, I made silicone phantoms in Ecoflex 00-10, 00-20, and 00-30. I added white and red silicone pigment to my liking to make it "flesh colored" and then rolled each in baby powder to remove the tackiness.

I also laser cut new pieces of clear acrylic to act as my DIGIT window based on the DXF file available in the DIGIT repository. since my existing ones were either scratched or otherwise hard to clean. This took longer than I care to admit in the PRL lol. I also found out BDML does not have PTA with the PRL, and it is possible that we might want to do that for the future. My laser cuts ended up great and I finally have a clean acrylic surface.

I then "glued" my elastomer to the acrylic window with Solaris and I accidentally melted my PLA pieces when I cured it in the toaster oven, oops. So I need to print a new DIGIT cover tomorrow morning since the Bambu was busy.

This is all looking promising, and I will try a real test tomorrow. Ciao!

02 August

Yesterday, I forgot to update my blog because I had a migraine and went home early to work remotely. Yesterday, I successfully made a shell elastomer out of Solaris coated with GEL. I have not tested that out yet, but it does not seem to be what I am looking for. The hollow shape really just buckles under compression instead of locally deforming, which is not what I am after. My next idea is to create a GEL shell and fill the middle with Solaris for extra durability, which might end up working well assuming the layers successfully cure together and I am able to actually extract it from the mold in one piece. Fingers crossed. Yesterday, I was also able to get my code up and running in the way I want it which was a hug success. The only thing I want to edit in the code is to have it take frames from the DIGIT after the stepper motor has paused for like 0.5 seconds instead of when it just pauses. I also want the stepper motor to move slower and pause longer, as I think it is moving at a bit of an aggressive pace right now. These are easy tweaks to make considering the bulk of the code is already in place and running.

Update: I think this combo works pretty well/looks promising. The different layers of silicone did cure together. However, the spray paint technique for coating is not the best. It crackles and wrinkles upon deformation which is of course not ideal. I need to find a better method for a reflective coating. Next week I will experiment with different combos of psycho paint/Al powder/NOVOCS Matte. Then, fingers crossed, I am finally ready to go.

31 July

Today I spent quite a while fiddling with my code so that I could get the stepper motor to pause in 10 increments so force data can be vibration-free. I successfully got that code up and running and the stepperMove_increment code is here. I was also successfully able to print my shell mold today, I think the issue was the expired resin. I made a quick batch of Solaris and poured it in with no mold release or any further polishing of the mold itself. I do not think we have any plastic polish in lab so I am going to bring in toothpaste tomorrow and see if that does the job for polishing. As expected, the gel got stuck to the mold. I was really hoping it would not since it is pretty smooth, but alas I was wrong.

Overall, I am getting my code in its final stages to take some data and still working on the elastomer design. I am also going to buy the camera board and lens set the RoTipBot people used because it is not very expensive and I think it would be good to try something like that. The images I am getting from the DIGIT camera are very sub-par, and I think we could do better with crisper images.

Also, in the background, I am trying to reconcile the discrepancy I saw in reported cervix stiffness values and anecdotal evidence. I am going to try and find more papers with reported numbers and reach back out to my collaborators in OB/GYN to see if they know more.

30 July

Today I started off with some data analysis from the frames I captured last week with the DIGIT sensor. I just wanted to see if the contact patch area analysis I did during winter/spring quarter would hold up here and it does! I made some tweaks to the HSV ranges for magenta, blue, and green, since the colors appear slightly differently considering the elastomer is not translucent anymore. I also made one more tweak to this code to have it filter out the teeny tiny contours that appear around the edges of my area of interest, adn then take the same convex hull to elliptical fit approach that I did previously. The code for that is here, and I have linked some representative images of my analysis here with force-torque data.

I also attempted to add another serial communication line between the arduino and linux laptop today so I can take frames with the DIGIT while the stepper motor is paused so I no longer get vibration noise with the ATI. However, when I attempted to install the Arduino IDE onto the laptop, I caused it to be very unhappy and it went into a "kernel panic" and refused to boot. With the help of Mark, I was able to create a bootable Ubuntu USB drive and boot the laptop up from that, so all is well with the world. I still do not know what happened there, my best guess is that this was a really old version of Ubuntu and it was just not compatible with my Arduino download, but anyway it should not have caused the whole laptop to crash. It took me a long time to figure out this issue, but I was finally able to successfully get arduino up and running on the linux laptop, so huray.

My shell mold print from yesterday failed when I came in this morning which was disappointing. I am not sure why this is since I was not the one to take it off the printer. The printer was busy all day today so I will try again tomorrow. I believe the resin was expired that I used, so I will try again with new resin tomorrow and hopefully it will be good.

Cheers to another day.

29 July

Today I started off with the bi-weekly tactile meeting, where we spent the majority of the time talking about our proposals for the HAI seed grants (due Aug 12, coming up soon!). Right after I finish this blog post, I am going to spend some time going over it and making some edits. I also talked a little bit about what I have been up to this past week, which was mostly trying to make clear and super soft elastomers for optical tactile sensing. If you have been reading my blog, you know my tale of woe, but essentially I have found something that sort of works but can be better. I want to follow in the footsteps of RoTipBot and create an elastomer shell. I created a CAD model for the shell mold and it is currently printing on the Form3 with 0.05 mm resolution. I need to get this mold's surface as perfect as possible, so I am going to polish it and apply lacquer to smooth it when it is done. I want to try two things with this shell:

1. Fill the shell with nothing but air
2. Place a hard surface underneath the shell (like an excised portion of a glass/acrylic test tube)

I also just got the thought about pressurizing the shell? I am not sure what that would really do for me but it is another idea I guess. I guess that way you could fine tune the resistance of whatever is inside of the shell if you end up needing something that is between glass and normal air. That could actually be really interesting for my application, since I am attempting to determine the mechanical properties of tissue that changes stiffness an order of magnitude or so. You get maximum sensitivity on these types of sensors when the stiffness of your sensor roughly matches the stiffness of your sample. That way you could more easily control the effective stiffness of your sensor without having to swap any parts. Anyway, this is just a half-baked idea and I will think more about it.

Also per my conversation with Mark last week, I am changing the function of my test set-up to pause as the DIGIT frames and ATI force data are being collected to rule out any vibrational noise I am getting from the stepper motor as it moves. I ran into a slight problem, however, as the computer connects to the Arduino via serial, and to the laptop over TCP. What I need to make this happen is the Arduino to have a second serial line connecting to the laptop so it can send messages when to take frames and such. I can't send the message to the computer and then to the laptop because as the stepper motor runs, so does the ATI which means the script is busy and cannot take in commands. Anyway, I got about halfway through this problem today and I will finish it up tomorrow.

Lastly, I also had my weekly "Thinking About 310" meeting with Mark today where we did some more, well, thinking about 310. We mostly discussed the fall schedule and Paper Bike ideas.

26 July

Based on what I did yesterday and pretty much all week, I wanted to narrow down the optimal solution for my silicone elastomer. I tried 5 different gels (a combination of different bases, reflective layers, and outer coatings), and noted my findings on the differnet elastomer fabrication methods here. In summary, EcoFlex GEL is soft enough to deform against my current cervix phantom and is optically clear. One big disadvantage of it, however, is that it is quite sticky which can cause rips in the gel base or outer coating if not careful. In my opinion, the gel that worked the best was the EcoFlex GEL base, Rustoleum chrome coat, then EcoFlex GEL top coat with white pigment and dusted with baby powder. The baby powder removes a lot of the stickiness, but I still found myself sticking to the gel a little bit and making small tears in the outer coating. I also got my items from Smooth On today, and tried out the process documented in the RoTipBot paper to coat my elastomer with a reflective layer. I definitely did not use as much powder (Aluminum or Silver Bullet) as them and got a really opaque coat, so I don't know why they are using so much. I personally did not think the NOVOCS Matte finish made a huge difference, but my gram scale was acting up a little, so I think I might need to try again with a more sensitive and reliable scale. Hao found a milligram scale for me today and I will try that coating process again when I get back to lab on Monday.

Although my gel was not perfect, I thought it was good enough to do some preliminary tests with the set-up I have been building in the background. So, I rigged everything up and gave it a go. I have a couple small problems with my set up:

1. The cable for the DIGIT gets in the way a bit, and for some reason I could not find a good tape to hold it down
2. I did not actually attach the gel to the DIGIT acrylic, I just stuck it on and let its stickiness do the work, so this was imperfect
3. For some reason MATLAB was not disconnecting from the TCP connection at the end of the code, so I had to restart my Linux terminal every time I wanted to run it again. I will have to look more into this, because it wasn't happening when I ran trails a couple weeks ago.
4. After the experiment is started, there is no option to send another command, so the motor holds where it is, and I would like it to retreat before starting the next run.

The data I look in this little experiment today can be found here. I talked with Mark for a couple minutes about it, and he thinks that my camera views are simply not good, and to look into other options for cameras, for example, here is the one the RoTipBot people use. He also thinks we need to find a better way to cast the gel onto the acrylic plate (and also keep the plate super clean) to get some better results. Anyway, there is still more to do and think about, as always.

25 July

I am updating for today and yesterday. Yesterday I had a good chat with Mark about the state ogf my project. Basically the gist of it is that I should keep going and trying to learn as much as I can while still being open-minded about the specific technology applications. Based on the literature and the people I have spoken to, I do believe there is a need here to measure the mechanical properties of the cervix during pregnancy, and I think we have only begun to scratch the surface of its importance.

Today, I attempted to make a new gel with an EcoFlex GEL coating instead of 00-20, because I found that the 00-20 was not soft enough to deform under light loads against my cervix phantom made of silicone. I also did some literature review on the stiffness of the cervix in vivo, which I know has been characterized via aspiration. According to the paper by Badir 2010 the closing pressure of a non-pregnant cervix is about 300 mbar (30 kPa), which honestly seems like a really low value. I then did some more digging, and there was a follow-up paper done in 2020 also by Badir where they generated 5 cervical phantoms from silicone. Their stiffest sample was made of pure EcoFlex GEL, which does not make a whole lot of sense to me based on anecdotal evidence of cervical hardness values. I wrote down my thoughts on the matter here. Anyway, it seems like the cervix should be harder than this based on the people I have spoken to as well as the cerclage training model I felt myself (quite stiff). There is either something I am not understanding about these measurements, or these measurements are not actually accurately reflecting the stiffness of the cervix. Something is up here and I need to do some more digging and talking to people.

Update: the EcoFlex GEL was too sticky and provided no benefit (or even less benefit) than the EcoFlex 00-20. I need to find a way to make the Solaris softer without compromising the clarity

23 July

Today I began writing my personal statement for the DAAD grant so I can study in Germany with Roberto Callandra's group next summer. And, now that I am getting ever-closer to doing some actual experimentation with the DIGIT sensor, I created an experimental plan for what I want to accomplish. I also had a meeting with Madhavi today to go over some financials and to-do items for 310 in the fall.

Today I did some more experimentation with spray painting my elastomer. I thought that maybe because my elastomer is hemispherical instead of the flat-ish shape it used to be spray painting might work better. I attempted to do a coat with the old Rustoleum Aluminum paint I found in the 310 loft (I have no idea how long it has been there, so...) but it did not work very well. Just like last time, the paint crackled when I touched it and it left weird streaks on application. This might partly have to do with the fact that the paint is old. I also got a surprise shipment of the spray paints I ordered from Amazon last week in perfect timing! I used the Rustoleum Metallic Chrome Finish paint and it immediately looked so much better than the aluminum finish paint I borrowed from 310. The paint went on decently smooth, although I did notice some pooling at the top. In my first attempt, I placed the elastomer inside of a metal tray, so I had to reach around the rim to really paint the sides well, which was a mistake. Before the paint was totally dry (I was a bit impatient), I covered it with Ecoflex 00-20 with white pigment, and then placed it in the vacuum chamber. This proved to be a mistake, as apparently spray paint lifts from surfaces under negative pressure, which left weird bubbling in my surface which was no good.

I then took some IPA and washed off my first attempt and tried again. I placed the cleaned elastomer on top of the tray this time and lightly sprayed around it, getting a more even coat. I then mixed up some Ecoflex 00-20 with white pigment while the paint was drying and degassed it before I coated the elastomer. Then, I dripped the degassed Ecoflex onto the elastomer and let it sit outside to cure (it took about 20 minutes). I then took a razor blade and cut the excess Ecoflex off the metal tray to try and not detach it from the elastomer. After it was removed from the tray, I cut away the excess coating with scissors. Some room for improvement here is to place the elastomer on parchment paper so it peels away instead of cutting it off the surface of the metal tray.

To summarize, this is my new and improved method for coating the elastomers for tactile sensors:

1. prep the elastomer surface by cleaning with IPA and let dry completely
2. mix Ecoflex 00-20 with white pigment until opaque (about 2 g will do) and let degass
3. go outside and place the clean elastomer on top of a metal tray and evenly spray paint it with Rustoleum Metallic Chrome finish. It may take a few coats to get opaque build up. Let this dry for a few minutes while your Ecoflex is degassing
4. Take the degassed Ecoflex and pour it over the spray painted elastomer, being sure to cover every surface. Let cure.
5. Cut away the excess Ecoflex coating with a razor blade, being careful not to rip at the coating. Once removed cut away all excess coating with scissors.
6. if necessary, clean the bottom surface of the elastomer with IPA

22 July

It looks like I forgot to update my blog at the end of last week, oops. Nothing too crazy happened, except that I learned how to order things through Gosia and Amazon Business. I was also able to contact one of the suppliers of Smooth On Inc, Reynolds, and order some powders and solvents through them for the reflective covering of my elastomer. I am currently waiting for those to come in, and when they do I can finally assemble my elastomer and start my experimentation.

Today I had a meeting with Mark regarding planning for 310. I also worked on the hardware for my experimental set up by printing new holders for the ATI Mini and the samples to reduce slop in the system. I made the sample holder slightly smaller and thicker to be more sturdy. I also made the ATI Mini holder a little thicker to be more sturdy and reduced the hole size of where it attaches to the stepper motor to reduce play. Now my system seems quite sturdy for the amount of load I intend to apply. My OnShape files can be found here.

I also found out this morning that I was accepted to the Touch Sensing and Processing Summer School at TU Dresden in the first week of September. I am very excited and spent a little time looking at flights and logistics. This also reminded me that I need to work on my submission to DAAD if I would like to study in Roberto's group at TU Dresden next summer, so I created a doc with basic information on the fellowship application requirements. One of the requirements is a personal statement, which got me thinking a little bit about why I am so passionate about my research. So, I am doing a little reflecting on my experiences and observations to actually be able to articulate why I think this research is so important and why I would like to continue it specifically at TU Dresden for a short time. I will get back to you with updates on my reflections.

17 July

First things first, I took care of business. All my files are now housed in the BDML team drive after a painstaking 1.5 hours of copying, downloading, and moving. However, one annoying thing is that I cannot move or delete files/folders once they exist. As promised from yesterday, here is a link to the folder containing my code for the stepper motor/ATI/DIGIT controls.

After that I moved onto some redesigning of my experimental setup for the DIGIT experiments. I needed to create a way for the DIGIT to attach to the ATI, so I created these two complementary pieces, ATI attachment and DIGIT Attachment that screw together. I left 10 mm of space between the two to account for the micro USB DIGIT connection (which annoyingly goes so far out the back), so hopefully that will be enough space while still having the whole set up be sturdy.

After that I did a little thinking and writing in my notebook of what I actually want CERVA to look like and do. One thing that I have been thinking about recently is the potential for CERVA to be a cervical imaging device as well as a tactile sensor, which means the elastomer would either have to be transparent in some cases or there would have to be an alternate lighting/imaging source outside of the elastomer. I like the latter a little better to start with because from my very preliminary research, silicone is transparent in the infrared light regions which initially posed some safety concerns for me, because infrared light can heat things up and degrade collagen and elastin which are not desirable outcomes here.

So, I got to thinking a little more about how we could have two lighting and optical transmissions, and one thing I would be interested in is having some sort of lens/illumination outside of the elastomer so we can see where we are going and alternatively do some medical imaging sort of like an endoscope. Anyway, this is all stuff to think about while I am waiting to get set up for my DIGIT experiment.

17 July

As promised from yesterday, I made my dummy program to read and write data through TCP/client connection, and I built more intuition for it. I was able to get my original code working after doing this and I can now control the stepper motor, DIGIT sensor, and ATI force sensor between both the medical devices computer and linux laptop. I also helped Grace with some serial connection stuff she was having trouble with. In MATLAB, the command to read a serial port is readline(device) and the command to write to a serial port is writeline(device, command).

I am also switching gears with the shape of my elastomer for the tactile sensor considering I will be pressing against a soft surface, and the flat-ish shape of the DIGIT elastomer is not giving me much to work with. So, I am making a cover that will go over the acrylic piece of the DIGIT sensor with a 15mm diameter hole where I can fit my elastomer in. I am using a hemispherical elastomer and borrowed a mold from Julia for this.

I also realized that I need to switch ownership of all my google drive files to be stored in the BDML shared drive. I am in the process of doing that, so Mark, if you are reading this, I promise I will link copies of my code when I place them in the right place.

16 July

I spent a good portion of my day doing literature review. I wanted to learn more about the manufacturing processes of different optical tactile sensors, and my summary is https://docs.google.com/document/d/1wqcZUQLVzVRENhRHhtx1dg2IRVN3RPPw8IpRTeQ5mMA/edit. I also spent some time working on my code to connect the medical devices computer and linux laptop to send and receive data over socket. I successfully got the computer to send data to the laptop, but I am having trouble sending data from the laptop back to the computer. Tomorrow I will try what Mark suggested which is a dummy program following a tutorial on sending and receiving data over socket so I can get a better intuition for it.

15 July

Today we started with our biweekly tactile meeting. I showed the group some of the silicone samples I have made to attach to the DIGIT sensor. The general recommendation is to do some research on the different fabrication methods of the different sensors and why this is (for example why does DIGIT not use a reflective coating while GelSight does). I also shared with the group the adventures I have had getting the ATI to work on Linux, as it seemed the issue was the medical devices computer being out of date to install the right packages for the national instruments drivers. So, I tried to install the drivers again on the Linux laptop (after getting the wifi issue solved again through Mark's help of finding a wifi USB thing). Unfortunately I ran into the same issues and the download of the specific package I need: ni-daqmx would not download. For the near future, I believe I will keep my current set up of using the Linux laptop to collect DIGIT data and using the medical devices computer to collect ATI data and communicate between the two over wifi.

My other task for today was to figure out an optimal solution for coating the transparent silicone gels with a reflective coating and/or white opaque ecoflex. I explored a couple methods today:

1. Coating with just ecoflex: this ends up as translucent in thin layers like the DIGIT sensor, however, I feel like I did not get as crisp of an image when compared to the preliminary images I got on Friday with the metallic powder coat
2. Reflective coatingt: Right now I am using the Rustoleum aluminum finish paint, but my issue is with the paint crackling on the surface of the gel allowing light to come through in random patterns. I tried to cover it with ecoflex immediately to not have it crackle and unfortunately that did not work. My next idea is to mix the spray paint into the ecoflex itself kind of like what I did with the metallic powder and hopefully it will be more flexible and not crackle that way.

I also had a chance to speak with Danielle Panelli, a MFM specialist at Stanford. She feels the most valuable contribution to my project would be to differentiate between patients who deliver preterm who display symptoms of dilation and short cervices and who do not deliver preterm with these same symptoms. Overall, she thinks there is merit to a project like mine and knowing more about preterm labor and its progression is certainly important.

Update: mixing the spray paint with the ecoflex was not a good idea, it got clumpy and weird... oops

Update: the spray paint and metallic coatings I have right now are just too sparkly, so I think I need to either wait for the mirror finish one or possibly borrow a can from Monroe Kennedy's lab who also use it for DenseTact

12 July

Today I started off by doing some testing on coating my solaris gels with a reflective layer. We do not have any of the spray paint I wanted to use in lab, so I took an adventure to the loft and found some Rustoleum Metallic Aluminum paint. Julia recommended use the Rustoleum Mirror Finish paint, and while I am waiting for my purchase approval to go through, I wanted to try this. Julia also gifted me some Meyspring Silver Lining aluminum metallic powder that I mixed with some Ecoflex to try as well.

I was only able to try the sample of metallic ecoflex which was "too metallic" when placed on the DIGIT. It sparkled when hit with the LEDs which obstructed view.

I also had an issue when running the Linux laptop today as it would not connect to wifi. After spending some time with Seonghong, we were able to figure out that "secure boot" was enabled, and when we disabled it the wifi status magically fixed itself.

On Monday I will do some more experimentation with the final assembly of my new and improved DIGIT gels and hopefully start my experimentation.

11 July

Today I started by calling the NSF to get my fellowship sorted out, which of course was not frustrating at all! I guess stay tuned for updates here.

I also got some good-looking molds from my resurfaced DIGIT daughter molds, and I am attempting to make some good samples with these. I made three molds to speed up production of the gels and am going to try a few different things with them. One of them I will cast as normal, one I will put the acrylic plate on the back while it is still curing to try and bond it, and the last one I am going to cure without applying heat to see if that improves the clarity.

On the software side of things I tried and failed to install a National Instruments driver on the medical devices computer, and seemingly the issue is that our version of Ubuntu is out of date. I think the easiest thing to do moving forward is to actually use the medical devices computer to run MATLAB and send commands to the Arduino via serial and connect separately to the laptop running Linux with Python to sen commands to the DIGIT sensor to take frames at specific intervals.

Update: I was finally able to et in touch with the NSF people who sent me a rather snarky email back stating that I will have another opportunity to update my status in August, so thanks I guess.

10 July

Today, I spent the first part of my day organizing all my thoughts for this project and also getting the "story" right for what the timeline of research has been and development of methods for PTL prediction and prevention. In between this, I was also attempting to again cast silicone into the DIGIT-shape using solaris and the original DIGIT gel as a daughter mold. I did have more success with this today. First, I covered the original DIGIT gel in a thin layer of Mold Star to smooth out the surface (it got cracked and scratched from repeated handling). Then, I sprayed this surface with a generous coat of mold release and stuck it face-down in a pot of degassed mold star. The mold came out pretty good and I made some preliminary samples with solaris in this mold. In my first attempt, the top part of the gel got stuck in the mold although I applied mold release, so on the second attempt I applied a "very" generous coat of mold release which allowed the gel to slip out, however, it has a surface texture from the excess drops of mold release. I will try again tomorrow to find the right balance and to also make more molds to speed up the process.

In terms of my clerical tasks, I need to call the NSF GRFP people and see if they can help me after a month of ghosting. I meant to do this today but got distracted, so tomorrow morning it is.

9 July

I got back to Stanford this morning from my extended 4th of July weekend in LA with my family. I played a lot of golf including the US Women's Amateur Qualifier, where I shot 73 (+1) which did not make the cut, but nonetheless I am proud of myself for keeping up my skill and putting myself out there. Onto new adventures! Today I am focused on fixing my DIGIT gel molds so they will have smooth surfaces. Unfortunately my molds last week had air bubbles and I did ruin one by forgetting to put in mold release, oops! My current plan is to glue the corner of the original DIGIT gel back together using silicone since it ripped. Then I will spray it with mold release (for real this time) and try to press it into my existing mold with a little bit of silicone to create a fine layer to cover the air bubbles. I will also try to make a new mold entirely.

I also did some preliminary research on IVF embryo implantation mostly because I was just curious. It turns out that implanting the embryo in the precise location is a little bit of guess work on abdominal ultrasound guidance.

Lastly, I attempted to replace the batteries in all the multimeters but was only successful with two and I did my financial training so I can make purchases.

Update: "gluing" the gel back together with silicone did not work Update: new mold did not form properly (there is a piece missing in the original gel that the silicone filled in) Update: resurfacing of air bubble mold kind of didn't work either. The silicone just stuck to the original sample rather than the mold, so I tried again but instead removing the original gel from the mold this time after pressing it in to get the excess silicone out. It sort of worked. My silicone sample actually turned out pretty good except one of the top corners ripped off and took the protective covering on the mold with it. I am going to try this same method with the solaris instead of the mold star, since I have found that solaris sticks to the mold star pretty well.

My next idea is to resurface a digit gel and use that as my new daughter mold. The idea here is to rely on gravity to smooth out the surface

2 July

This morning I spoke to Yasser El-Sayed, the head of the division of MFM at Stanford. The summary of the conversation is linked in interview notes. The TL;DR is he doesn't think tat doing my thesis in preterm labor prevention has very much clinical impact or translation and encouraged me to explore other avenues. Then, this afternoon I spoke to Yair Blumenfeld who reminded me I am in this for an academic endeavor and what I can learn from this is valuable regardless of the clinical outcome. He seems to believe there is value to a project like this and encouraged me to talk to more OB/GYN faculty to find other applications for a device of this nature. He also encouraged me to reframe the needs statement of my project to: alternative sensing for prediction of preterm labor in cases of long cervices at 20 weeks. Anyway, I will continue to do more learning and talking to people as well as continue to develop my technical skills. Today I also attempted to make some DIGIT-compatible gels with Solaris using the DIGIT gel to make a daughter mold. This afternoon I leave for LA to go home for the 4th of July and my golf tournament.

1 July

Today I was able to control y stepper motor in Arduino through MATLAB over serial. My next step is getting the ATI mini to run on linux so I can pair it with the DIGIT sensor. I tried to run the DIGIT on windows with no luck. I need to find out what to download to the PC so I can use the National Instruments driver with the ATI. I also started helping some of the summer students get more familiar with Arduino through Tinker CAD.

26 June

It looks like I forgot to update my blog on yesterday. On Tuesday the 25th we did the second installment of the lab cleanup which took most of the day. I also 3D printed some parts to go on my camera and ATI Mini for my experimental setup. I have to do the purchasing training in order to buy anything else for my project (and I need some LED lights too). Today I had Jazmin make an Arduino code to run a stepper motor for a particular distance and for a particular speed. Mark and Hao helped her with this task as well as there was a power supply issue as well as a grounding issue in the circuit. Overall, we got it worked out and the motor driving correctly. I also experimented with some filtering to help out the ATI force readings, and using a Butterworth low pass filter seems like the best option so far. My next steps are to complete the tactile sensor on the hardware side and get it properly attached to the ATI and stepper motor and to work on time syncing for the various parts of the test setup (stepper motor, ATI data, video data).

24 June

Basically no research got done today with the lab cleanup taking place. But we completely reorganized the medical devices corner, yay!

21 June

Today we started off with an impromptu meeting to discuss projects for the SURFs and SURIs for the summer. I also had a meeting with Lauren Shluzas who was on Materna Medical. She gave me some great advice on people to reach out to who might be interested in my project and said that there are probably funding opportunities within Stanford Biodesign for my project. Later in the summer I will reach back out to her for more advice. Then, I went ahead and continued making parts and printing for my test set up with the ATI Mini. My gelatin from yesterday did set, however, I forgot to grease the mold so it turned into goo when I tried to take it out. I think I need to not only grease the mold but make a flexible version of my cervix phantom mold for easier release of these softer hydrogels. I also talked with Julia about DIGIT Pinki for a little bit and I am going to try to make my own macroscale version to play around with then get to the smaller version later.

20 June

Today I made a 3D printed attachment for the ATI mini to sit on the one axis stage so we can do some controlled force and displacement testing on a phantom. There is also something up with the Bambu printer because my first try failed printing and my second and third tries had rough finishes under the supports. The CAD model of my part is here and the CAD file for the ATI Mini 45 is here. For my phantom, I whipped up some 10 wt% gelatin and put it in a cervix mold I made last quarter. However, I think I messed it up and I am not confident it will gel but we will see after it sits overnight. If I am going to keep making these hydrogel phantoms, I will either need to do it in another lab or acquire some stir bars, a celcius hot plate, weigh boats, and a mg scale.

19 June

Today I spoke to Luis Garcia about CERVA. The notes of this interview can be found in Interview notes. Overall, he seemed enthusiastic about a project in this space and there is a definite need for more devices that can give us better prediction of preterm labor. One interesting thing that I did not know before speaking to him is that there's essentially no treatment to stop preterm labor once it starts (besides controversial progesterone). He also seemed adamant that there is a need to update the cerclage, and I agree with him on that. I had my one on one meeting with Mark today also and we discussed the cerclage idea and essentially we came to the conclusion that Ali's cuff sensor with a biocompatible adhesive would probably do the trick. I also got the ATI Mini up and running on the sensor bench computer (yay!) and was able to find the correct calibration constants. My files for this are under "Annie" on that computer.

18 June

After getting back from the dentist, I spent the first part of my day participating in the lab clean up. I then went to refine my interview questions for physicians considering I have my first scheduled meeting tomorrow. I then went on to beef up my literature review. I focused on finding any and all new tech related to this problem and aside from a slew of biomarker kits out there (usually used to measure fetal fibronectin or placental alpha microglobulin-1) the two main techniques out there today to measure biomechanical properties of the cervix are elastography and aspiration. I found that there is a product out there from Samsung Korea called E-Cervix (ElastoScan for Cervix). Furthermore, there is Pregnolia on the aspiration side. I would like to do a risk and benefits comparison of each of these techniques and dive a little more into how they fundamentally work so I can find the gaps in this space.

17 June

I spent most of the day organizing a list of OB/GYN (and specifically MFM) specialists at Stanford because I have some outstanding questions I need to ask more people based on the brainstorming conversation last week. The list of organized faculty and who I reached out to can be found here. I also created a broad and unrefined list of questions I want to ask the people I reached out to here. Lastly, I attempted to hook up and run the ATI Mini with little luck today, but will try again tomorrow.

14 June

Coming off of the brainstorm session yesterday I am deep in the ambiguity of this project, so I decided to list out what the ideal characteristics of a solution to this problem would be. The greater scientific community thinks there is value in determining the mechanical properties of the cervix throughout pregnancy. However, one of the biggest concerns I have seen is that people are incredibly weary of anything actually touching the cervix! It is impossible to get mechanical properties without manipulating the cervix in some capacity, but I wonder if we could be more clever about this. "Cervical ripening" is the first or one of the earliest stages of labor. There is evidence that suggest the cervix ripens before it shortens, effaces, and dilates. But, what is the underlying mechanism for this ripening? Ultimately, collagen architecture breaks down allowing the tissue to be softer and stretchier. There is also evidence of increased water content in the cervix that helps disrupt that architecture. While the actual pathophysiology of this is unknown (at least based on my limited search) these are real things within the tissue that we could see.

I wanted to see if we could actually image collagen in a handheld way in vivo and didn't find anything in the literature. It seems that the best microscopy technique for imaging collagen is second harmonic generation (SHG). Collagen fibers are quite small (nm scale) so a setup like this would probably be really challenging and expensive.

Next, I wanted to see if we could image water content, and it turns out we can through Near Infared techniques. Water absorbs light at around 1000nm, and people have looked into in vivo imaging of water content in biological tissues. Basically, people rely on photoacoustic imaging where the water absorbs light, gets discreetly heated, then thermal expansion causes an acoustic response which can be read by an ultrasound transducer (or possibly an optical fiber with FBG to make it ultra small??). Yan et al showed this in excised tissue samples.

Anyway, I think there might be something here but I need some help flushing it out and understanding the solution space better.

13 June

It is officially summer, woohoo! With my ME310 spring report officially in the books I can finally do research again. Today I am focusing my efforts on a literature review. I started with the question, "What is the state of the art technology for determining prediction of preterm birth?" but ultimately decided to pivot to a more fundamental level. I am getting a better picture of the causes and prevalence of preterm labor and working my way up to tech.

In the afternoon, we did a brainstorming session with Ali, Julia, EmJ and Mark. We talked a lot about the problem and the general conclusion is that we need to learn more. The point of this conversation was to see if DIGIT Pinki can actually provide a solution to the problem at hand or if it is actually more of a "tech push" onto this problem. Ultimately, we have to think a little bit more about this. One interesting thing that I want to look into more is the use of optics to infer mechanical properties of the cervix.