Bio-MEMS - Science topic

Hello,

I'm interested in research in fiberoptic biosensors, MEMS AFM microscopy, photonic biosensors.

If it is no problem could you suggest the cutting-edge area research fiberoptic biosensors, MEMS AFM microscopy, photonic biosensors for a research proposal?

The premise is such that we have two independently fabricated su8 fluidic structures, we want to integrate them by bonding them together to make them functional. Any insights, standard protocols, or even brief thoughts on better ways to achieve SU-8 to SU-8 bonding by using any methods, chemical, physical, etc will be highly appreciated?.

Some patients exhibit unusually fast or chaotic heartbeats and thus are at a high risk of cardiac arrest or a heart attack. An implantable defibrillator restores a normal heart rhythm by providing electrical shocks to the heart during abnormal conditions. Conventional pacemakers work at fixed rate. What will happen if the patient is a football fan (extremely active and excited)?

I'm looking for polypropylene microspheres to use them in microfluidics. I will appreciate for any help.

I have used TNS & TMS & TACS systems which resulted in the patients awakening.TDCS was a bit effective but even this caused the patient to wake up after some time .

Would be interested if someone has studied the electrical charge distribution of the nanosized viruses and even of micro sized bacteria.

Indeed, if they are electrostatically charged or even induced we have the possibility of a simple collection centre for these through highly charged electrical spheres hanging inside open or closed spaces where the virus would be attracted to. The heat treatment intermittently will keep destroying without any effort to clean or collect the residue.

I am looking for material which need to fit several criterias.

*high flexibility

*bio-compatible

*low conductivity

*Compatible with litho process.

Our team are working with PI2611 now. However, its flexibility is not really fit our request in the next generation design.

Therefore, can anyone suggest me some other materials that might work?

Thank you very much.

I am simulating a diaphragm pump in comsol and want to know to apply the electric potential to achieve the right displacements.

convolution network an be substantially deeper, more accurate and efficient to train if they contain shorter connections between layers close to the input and those close to the output .how are densely connected convolutional networks?

Can I fabricate same height of main channel(h=5um) and narrow channels(5um) which is joint between two main channel(5um) through multlayer lithography?.kindly give valuable suggestions.thanks

We are designing a MEMS pressure sensor for long-term use, hopefully years, underwater. Possibly saltwater as well. The device has metal traces and uses a typical method to measure pressure.

We need a passivation layer to protect the electronics from water and the external environment. Research papers in this topic each have very different opinions as to what layers, in what order and thickness to use. Some recommend SiNx, or SiO2, or SiON, or combinations of these layers in varying thicknesses.

Is there a good way to pick the passivation stack besides picking a few different layers and thicknesses? What are the pros/cons of using SiNx/SiO2/SiON? Can you recommend a particular stack for my application?

Micro-electro-mechanical Systems are used as trasducer. But what is the exactly way they mesure temperature?

An endoscopy and colonoscopy are usually unpleasant for many of patients. For this reason, scientists are now trying to use”Capsule endoscopy”.

I want to know what problems might arise in their design?

If Beethoven was alive today, which technology would help him to hide deafness?

According to statistics, 80% of those who could benefit from a hearing-aid choose not to use one. One of the most important reasons for that, is the social stigma associated with common misconceptions about wearing hearing aids. How can bioMEMS help to fabricate miniaturized hearing aids without compromising performance?

The electrodes are used for voltage measurement in the Brain and needs to be connected to pre-amplifiers.

Is there any company or research group that can fabricate transparent microchip for this purpose?

I want to simulate an electrostatic-driven staggered comb-drive actuator. I set the boundary conditions and vary the potential to get the deflection angle. There is a great difference (>50%) between analytical solution and simulation of vertical comb drive using COMSOL electro-mechanics module.The COMSOL file is attached.

Thanks in regard.

Hello everyone,

I am experiencing a problem with double layer microfluidic fabrication. I am going to eventually use this device on human cells, thus the environment needs to be appropriate. I have been seeing some particles due to punching the inlet/outlet holes of the device. Has anyone had this experience before? I am new to two layer device fabrication, thus any tips on cleaning the holes after punching/the actual punching method, etc., would be appreciated.

Any tips on multilayer soft lithography protocol would be great as well. If there are researchers who can share their protocols, tips and tricks?

thank you and have a great experiment everyone!

Hi,

I use PDMS (Sylgard 184) to make Micropillars. In order to make them more flexible, I need to reduce the elatic moduli of the meterial. 

I see from this paper(see attachment): Mechanical properties of silicones for MEMS (F. Schneider et al), that they added a thinner to their PDMS products (both RTV 615 and Sylgard 184), and the cured silicone with added thinner has a lower elatic moduli. However they didn't mention exactly which thinner they used in their application.

I read from the document of Sylgard 182 that the Dow Corning 200 Fluid 20 cS can be added for lowering the viscosity. However I don't see such description in the document of Sylgard 184, and I'm wondering if this fluid can also be applied to Sylgard 184 for the same use (I already contacted Dow Corning, however till now nobody answers...So I think perhaps I can first look for some help here). Also, can it be applied to Sylgard 186?

Or do you have any other suggestions concerning the thinner for Sylgard 184?

Thank you in advance!

I am using SU-8 2015 for my microfluidic channel structures. The substrate is 1mm thick glass wafer. 

Issue : SU-8 flows off the substrate during the developing process. The adhesion is poor apparently.

Solution/s to this problem are needed.

The protocol I am following is as follows.

1) Cleaning and dehydration bake of the wafer.

2) Spin coating of SU8 of desired thickness.

3) Soft baking process. 2 mins at 65C and 5 mins at 95C.

4) Exposure using MA-6 Mask Aligner.

5) Post Exposure baking. 2 min at 65C and 5-10 min at 95C.

6) Developing in solution for 1min.

7) Rinsing with IPA and drying with Nitrogen gas.

i am doing research on RF MEMS switches, can any one help me to choose the best option of choosing the Actuation, Structure,and remaining all parameters.

i am attaching one form to this post, who are good in this please fill it.

is there any examples on RF mems switches please let me know

Hello,

I am doing a Passive Particle Separation application in PDMS microchannels. Due to the nature of the process, I am using quite high volumetric flow rates (up to 2.5 ml/min in a 40µm x 500µm microchannel.) The main problem that I have at high flow rates is the leaking of the fluid between inlet fittings and PDMS (i.e., There is no problem about the plasma bonding which I used to bond PDMS and glass base.)

Firstly, I though that the metal fittings that I have used (which can be seen at the image below) are so thin which makes the flow even faster at the inlet of the microchannel and it leads to leaking. For this reason, I decided to use wider plastic fittings to connect my microchannel to the syringe pump that I have been using. However, at this time, PDMS has teared when I was punching it with a wider puncher compatible to the wider plastic inlets. Later on, I decided to place the plastic fittings on the photoresist mold and then cast PDMS to eliminate punching process. At the end, I obtained a PDMS channel integrated to plastic inlets; however there was again leaking between plastic fittings and PDMS.

In all these cases, I used silicon grease around the inlets to isolate little cracking around the inlets through which leaking occurs, but I did not work neither.

Are there anyone who have also experienced this kind of leaking problem, and found a possible solution? I am eager to listen their recomendations.

Thank you in advance,

Utku. 

Dear All, I am trying to actuate the particle inside the microfluidic channel by SAW but my current function generator can only generate a 20MHz signal.

The diameter of my particle is around 8 micron.

In the first paper, they show the relationship between particle diameter and frequency. http://pubs.acs.org/doi/abs/10.1021/ac402607p

From their formula, 2 micron diameter particle was deflected with 280MHz or upper

But the another example is standing wave,

They manipulated 1.9 micron diameter particle with 38.2 MHz

I am so confused. Do they define "particle movement or deflection" with a different meaning?

If I need to control particle at the center, which frequency should I use?

Last thing, how can I know the estimated power I should use in particle deflection?

Since my equipment and the size of microchannel etc. are different from the other papers.

Best Regards,

Yannapol S.

Dear All,

I am very interesting in controlling number of cell in droplet,

In this paper, they used statistic model to predict number of cell in the droplet  

Any other ways to control number of cell in a droplet ?

Appreciate all comments....

Best Regards,

Yannapol S.

What is the best solution for elimnating air bubbles in the micro channel?

I have a trouble for bubble elimination in the micro channel for a long time.

I employ some method refer to other researchers.

1. use reagent such as BSA before experiment and washing

2. operate desicator with pump for 30 minutes before experiment

3. stay in refrigirator about one day before experiment

However, above methods are not perfect totally.

Or I use above methods as wrong way.

Please, recommend bubble elimination techniques what you employed.

I fabricate PDMS micropillars with LIGA-made casting mold (Nickel Metal Sheet) consisting sinking holes of 240µm depth and around 18µm diameter. My casting setup is as the figure attached. A cannula with a diameter 5mm is clipped tightly together with the casting sheet with one or two clips. Sylgard 182 Silicone for casting the pillars is moved into the cannula by a pipette. Then after the degassing process and the baking process the silicone becomes cured.

My question is concerning the peel-off process. Currently I first remove the clips and then put the whole thing into a vibrating bath (the bath is filled with isopropanol) and wait for the cannula with pillars and the casting sheet to become apart. The pillars are expected to be 240µm high (same as the hole depth). However, most pillars I get suffer from not enough height, that is they are torn apart after the silicone get cured. 

May I ask if anyone has similar experiences and do you have any suggestions concerning the peeling off process? Or maybe anyone has some other ways for peeling them off?

Thanks very much!

Is there any theory/explanation present for the sum-difference/nonlinear resonant modes in Microcantilever? Has anybody seen resonant peaks on the sum-difference frequencies of harmonics in Microcantilever?

I was growing hMSC (from Life Technologies) with alpha MEM and MSC certified FBS (both also from Life Tech.) and they were healthy for the first passage. But since early this week (second passage after 5days since seeded), the cell's morphologies began to change (lost their spindle shapes) and have grown very slowly.

I don't know if they began to differentiate, or cells were bad from the start

Any suggestions?