What is Screen Printing?



Hey guys! I know this is early in the week, but this is a post to explain the process of screen printing. A few people two weeks ago asked what exactly the screen printing process was, and I wanted to hold off answering that question so I could post this blog. I know what some of you are thinking right now, "this post is late, late, LATE!" And that I didn't post last week. But last week was technically my week off (I had to go to Texas Wednesday through Saturday and couldn't go to the lab to get all my required hours). I started working on this post last week, and I'm sorry that is so long. But there was a lot I wanted to talk about and share with you guys. So here it goes! :) 

What is screen printing? And how does one make screen printed electrodes? Well, screen printing is a technique in which an individual uses a stencil to spread ink onto a surface to get a desired design. And in my case, the desired design would be an electrode. In my previous post, I compared the screen printed process to baking. So I will continue using that analogy and list the "ingredients", steps, and baking time of each part of the screen printing process. So let's start, shall we?

First off, here are the materials needed in this process.

Materials Used

1. Stencils                        

2. Conductive carbon ink

3. Conductive Sliver        

4. Oven                             



                           

 Below is an outline of the screen printing process in the lab that I intern at. Dr. LaBelle created this so his students would know where the stencils of each part are, as well as know the steps of the process so no confusion ensues. Now I'll break each step down for you.

Step 1and 2  

Before I start the process, I go to the oven and set it to 100 degrees Celsius (it takes a really long time to bring the temperature up to that mark).

 So in the first step, I take the stencil #1 --which looks somewhat like a bunch of trees-- and put it on printer paper. Then I take the conductive carbon in, a black, thick substance, and spread it on the stencil. During this process, I make sure to keep a constant pressure spreading the ink across the stencil. This is to ensure each electrode made (the stencil makes 4) have the same amount of ink and bake properly.

Now I head over to the oven, place the paper with conductive ink on a metal rectangular sheet, and put it in the oven. And I bake it for 1 hour.

Here is a closer look at the stencil I used in step one.

Here is a closer look at the stencil I used in step one.

Here is the product of step 2

Step 3

Step 3 is exactly the same as step 2, except with a different materials. I use conductive silver, instead of conductive carbon ink; and I use the stencil shown below, instead of the one above.  I still scoop up the silver and use constant pressure when spreading it across the stencil. The most difficult part of this task is lining up the stencil on the electrode, and making sure the conductive silver doesn't run off due to its liquid form. After that, I go back to the oven and bake it for 1 hour at 100 C.

I need to line the stencil up to lines 3, 6, 9, and 12 of the electrodes.

Step 4

After step 3, I must now take the insulating ink and repeat what I have been doing for the past 3 steps. I take the stencil, line is up, spread the ink on, and then bake it for 1 hour in the oven.  

Insulating ink is a lot stickier than the previous inks, so I need to be careful spreading it on so that the stencil won't move while I spread it onto the stencil.

Step 5

 I know by now you think the screen printing process sounds really tedious. And you probably already know the next step I have to do: the same as step 4! I must complete my insulating circle on the electrodes by doing the same exact thing as step 4 and bake it for an hour. 

And finally, after 4 hours, I have my screen printed electrodes. So there you have it, the screen printing process. If you guys have any further questions about it, just ask in the comment section bellow. Until next time guys!

- Tina Smith









The Start of Something New

DAY 1     

Despite having previous experience in a biomedical engineering lab 2 summers ago, my first week of my senior research project was rather eye opening to the idea of what research actually entails; as well as, how different this experience would be compared to my overall high school experience.

On my way to ASU the first day, in the passenger seat of my sister's car, I found myself very concerned about my project. I understood the details of my project, but I felt flustered that I didn't have a well set out plan for it. Usually a task oriented and efficient individual, I was worried that there was no exact method in my mind to accomplish my goal. So I had to take a step back, take a breather, and re-evaluate my goals.

Firstly, I told myself I had to acknowledge that I knew very little about electrochemistry and the screen printing process (compared to everyone else in the lab). And that I must be ok with that. Secondly, I knew I needed to familiarize myself with the research and understand, in depth, what electrochemistry and screen printing was.  Thirdly, to not overwhelm myself with my project goals, I needed to plan mini goals within my project to help me answer my overall project question.

So this week, I set out with the mindset to accomplish those three tasks to be able to learn more vigorously in the lab. My first two mini goals were quite easy to accomplish. It didn't take long for me to admit my lack of knowledge in the field. And it also didn't take me long to discover what I needed to do to get rid of this lack of knowledge. My solution: my on-site mentor Dr. LaBelle and the library.

After emailing my concerns to Dr. LaBelle, he and I sat down in his office as he went through an electrochemistry 101 power point slide with me. At the end of the power point slide he then recommended which text book to check out and gave me a little homework. Yes, homework. Even during the Senior Research Project, one can't evade homework. I was to run a cyclic voltammogram (CV) and Ampomettric i*t (Amp i*t) on 3 solutions. He also gave me great advice to head by for the rest of my internship with him, "the best way to learn is to read a little and then go do it!" And so I went straight to the Noble Science and Engineering Library and got Electrochemistry by Carl Hamann, Andrew Hamnett, and Wolf Vielstich to start introducing myself to the world of electrochemistry.


DAY 2

Day 2 was definitely less stressful than the first. I had a set plan for that day to learn the basics of screen printing electrodes with one of Dr. LaBelle's students. Overall, I came to a very important conclusion: screen printing was exactly like baking. For those of you who don't know me, I'm a bit of a baking fanatic. So the comparison between screen printing electrodes and baking helped me understand the process more. With each layer I had to put on, I had to bake it for an hour, with a total of 4 parts.

Although I want to go into more detail of the screen printing process, I'll leave that for a different blog to give the process the spot light it deserves. This is because it requires more of an explanation than the general comparison I gave to you about baking.

After the 101 lab on screening printing electrodes, I headed to the library, of course, to read my text book. As well as figure out how I'm going to complete the homework Dr. LaBelle gave me for next week.

DAY 3

I worked a total of 3 days this week to complete my required 15 hours for my senior research project. Although I left off the previous day at the library, I started off this day at the library. Soon after I met with Dr. LaBelle again, where he spontaneously asked me if I wanted to learn about electroplating cooper and gold. Confused, I just nodded my head because it sounded cool. I found out, through Wikipedia of course, that electroplating is a process where metal cations are dissolved by electric current so that they form a metal coating around an electrode. I know this may sound intimidating, but I realized it actually fits into my project on screen printing. Because I'm screen printing electrodes!  

An then everything finally made sense to me about why I'm doing a senior research project.It is about embracing the things you have no knowledge on, learning a little about it, and re-doing that process over and over again.

OVERVIEW


I know I started off skeptical in the beginning of the week, but at the end of the week I grew more and more excited to see what a new day would bring at Dr. LaBelle's lab. I'm already so thankful that he took me into his lab, and has me working with extremely intelligent, and wonderful individuals.

I promise I'll upload the screen printing process in another post-- I have lots of pictures I took of it. As well as fill you in on how electroplating is going. Until next time guys.


- Tina Smith