On November 20, 2019, Deborah Borfitz’s BioIT World News reported that tissue chip models could replace animal testing and change the way of drug testing journey to clinical study. In fact, animal models can give misleading predictions for human responses to drugs. It results in wasting medical resources in drug development. One of the potential solutions to solve this issue is to develop physiologically relevant human tissue chips based on a microdevice. These in-vitro human organ microchips can also reduce drug developmental costs by reducing late-phase failures. The development of tissue chips can be achieved with help of microfabrication/microfluidics and bioengineering technology. 

Microfabrication & microfluidics applications in bioengineering

There are many microfabrication/microfluidics applications in bioengineering. The microfluidic gradient device is found in the cell culture systems. Droplet generation is used for the drug/gene delivery system by encapsulating the target gene or drug. Also, microfluidic technology is applied for drug screening and micropatterning. Microfluidic technology is used for the development of a biomimetic system (e.g., lung chip).  

Thus, microfabrication & microfluidics provide a new way to accelerate research in the field of organ-chip applications. It is expected that animal model study and human clinical trial would be replaced with the human tissue chip based on a microdevice.

This module focuses on the way how we can create a small microfeature (e.g., a microdevice to replicate human tissue physiology).

This module on microfabrication was designed to help students understand the general manufacturing process of microdevices to require special methods such as photolithography process, unlike macro-manufacturing process. This module can be used in junior/senior undergraduate courses including a term project and a lab project in mechanical/electrical/biomedical engineering major. The module will give students a great opportunity to design/fabricate/test a prototype of a microdevice and apply it for bio-applications in biology and medicine. This module will also help students develop their entrepreneurial mindset with curiosity, connection, and creating value through this module.

Deployment

The module introduces a photolithography method using economically inexpensive equipment as one method of microfabrication. This module includes a case study (e.g., micropatterning for cell culture, droplet generation, gradient generation, and a scaffold for the formation of cell spheroids). The detailed deployment is included as following;

1. Form a group (2-3 students per group).

• Define the role of each person
• Define a project topic
• Define a meeting schedule (e.g., bi-weekly meeting).

2. Literature survey

• Survey a commercially available product or a published product
• Read at least one research article.

3. Ideation

• Define problem statement in a project.
• Define about three potential approaches to solve problems (Curiosity).
• Conduct ideation (e.g., brainstorming)

4. Design and fabrication

• Draw conceptual & detailed design of a device (e.g., Solid-works and AutoCAD).
• Prepare a photomask by printing out the design on a clear film (e.g. OHP transparency film).
• Fabricate a template micropatterned on a substrate (e.g., silicon wafer) using photolithography technology once the mask with a micropattern is obtained.
• Conduct PDMS replica molding using the micropatterned template to get a PDMS microdevice with micropatterns.
• Bond it to a substrate (e.g., a microscope glass slide) via air plasma treatment or a stamping method using adhesive glue.

5. Test the function of the device.

• Connect the microdevice to a syringe pump using tubing.
• Test the function of the device by introducing fluid into the channel of the device.