Hashemi Lab       Iowa State University  
         
         Bio Microfluidics and
Optofluidic Systems
                                Mechanical Engineering  
                       
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  Funding from following organizations are gratefully acknowledged.    
   ONRArmyDOE     lush    ISU HASHEMI    
           
           
  On-Chip Development of Polymer Microfibers        
  We use a microfluidic approach to fabricate biocompatible polymer fibers with controlled sizes and cross sections.
Uniform gelatin microfibers with various morphologies are fabricated by increasing the gelatin concentration of core solution from 8% to 12%. Moreover, the increase of gelatin concentration greatly improves the mechanical properties of gelatin fibers; the Young’s modulus and tensile stress at break of gelatin (12%) fiber are raised about 2.2 and 1.9 times as those of gelatin (8%) fiber. The experiment results demonstrate that the decrease of sheath-to-core flow rate ratio from 300:1 to 30:1 results in the evolution of cross section from square to ribbon and the increase of fiber dimension. The increased size and shape evolutions of cross section from square to ribbon can not only strengthen the Young’s modulus and tensile stress at break, and also significantly enhance tensile strain at break.
In addition, Adult Hippocampal Progenitor Cells (AHPCs) are shown to successfully grow in vitro on PCL microfibers.

RSC Advances, 6, 55343-55353 (2016)
Journal of the Mechanical Behavior of Biomedical Materials, 61, 530-540 (2016)
RSC Advances, 5, 71203-71209 (2015)
Journal of Materials Chemistry A, 2, 4878-4884 (2014)

  microfiber microfluidics
neuron cell hashemi lab 2015 1 neuron cell 2015 hashemi lab 2
   
           
           
  Biosensor for Optofluidic Characterization of Cells and Particles        
  Analysis of the intrinsic fluorescence profiles of individual marine algae can be used in general classification of organisms based on cell size and fluorescence properties. We describe the design and fabrication of a Microflow Cytometer on a chip for characterization of phytoplankton. The Microflow Cytometer measures distinct side scatter and fluorescence properties of Synechococcus sp., Nitzschia d., and Thalassiosira p.; measurements are confirmed using the benchtop Accuri C6 flow cytometer. The Microflow Cytometer is sensitive enough to detect and characterize picoplankton with diameter approximately 1 μm and larger phytoplankton of up to 80 μm in length. The wide range in size discrimination coupled with detection of intrinsic fluorescent pigments suggests that this Microflow Cytometer will be able to distinguish different populations of phytoplankton on unmanned underwater vehicles. 

Biosensors
, 5, 308-318 (2015)

Analytical Chemistry, 84, 839-850 (2012)
Biomicrofluidics
, 5, 032009 (2011) 
Biosensors and Bioelectronics, 26, 4263-4269 (2011) 
Lab on a Chip, 10, 1952-1959 (2010)

Selected Press:  
Most Read Articles in 2012 Published in Biomicrofluidics
NRC/ASEE Research Publication Award

   
 
optofluidic
   
           
  Microfluidic Organ-on-a-Chip Technology for Advancement of Biological Studies        
  Drug testing targeted at the placenta has lacked reliable in vitro testing designs to mimic in vivo situations. With the plethora of different birth defects occurring around the world, attention needs to be drawn to finding a potential alternative to testing live subjects. Organ-on-a-chip technology has seen a vast increase in popularity, as the understanding of utilizing the properties of microfluidics has become more prevalent. Additionally, they are cost effective, use minimal product to create, and dodge the ethical dilemma of using in vivo animal models. Our goal is to create a microfluidic 3D cell culture system representing a “placenta-on-a-chip” in order to mimic the nutrient/waste transfer between maternal blood and fetal blood that occurs in the cotyledon section of the placenta, and to test and observe the effects of ethanol within the maternal bloodstream and compare it to a similar in vivo situation.

Advanced Healthcare Materials, 4, 1426-1450 (2015)

Selected Press:
ISU biotech research attracts funding
Placenta-on-a-Chip: Universal Drug Testing Using Microfluidics
Mechanical engineering graduate student selected for international NSF research program
              organ chi nastaran hashemi placenta    
           
  Energy Microdevices        
  Miniature microbial fuel cells have recently drawn lots of attention as portable power generation devices due to their short startup time and environmentally-friendly process which could be used for powering small integrated biosensors. We design and fabricate a microbial fuel cell in a microfluidic platform. The device is made in polydimethylsiloxane with a volume of 4 μL and consisted of two carbon cloth electrodes and proton exchange membrane. Shewanella Oneidensis MR-1 is chosen to be the electrogenic bacterial strain and inoculated into the anode chamber. Ferricyanide is used as the catholyte and pumped into the cathode chamber at a constant flow rate during the experiment. The miniature microbial fuel cell generates a maximum current of 2.59 μA and has a significantly short startup time.

Renewable & Sustainable Energy Review, 52, 1453-1472 (2015)
Physical Chemistry Chemical Physics, 15, 14147-14161 (2013)
Journal of Applied Biosensor, 1, 21-25 (2012)

Selected Press:
Featured as Key Scientific Article on Renewable Energy Global Innovations


  MFC    
  3D Paper-Based Microfluidic Devices for Healthcare Applications        
  The first step in curing a disease is being able to detect the disease effectively. The paper based microfluidic devices are biodegradable and can make diagnosing diseases cost effective and easy in almost all environments. We create a 3D paper device using wax printing fabrication technique and basic principles of origami. This design allows for a versatile fabrication technique over previously reported patterning of SU-8 photoresist on chromatography paper by employing readily available wax printer. The design also utilizes multiple colorimetric assays which can accommodate one or more analytes including urine, blood, and saliva. In this case to demonstrate the functionality of the 3D paper based microfluidic system, a urinalysis of protein and glucose assays is conducted. The amounts of glucose and protein introduced to the device are found to be proportional to the color change of each assay. This color change is quantified using Adobe Photoshop. Urine samples from participants with no pre-existing health conditions and one person with diabetes are collected and compared against synthetic urine samples with pre-determined glucose and protein levels. Utilizing this method, we are able to confirm that both protein and glucose levels are in fact within healthy ranges for healthy participants. For participant with diabetes, the glucose is found to be above healthy range while the protein level is in healthy range.

Renewable & Sustainable Energy Review, 52, 1453-1472 (2015)
Analytical Chemistry, 85, 10733–10737 (2013)

Selected Press:
Freshman finds success in SPEED


  paper-based microfluidics protein in urine    
paper bases microfluidic
           
Development of MnF2 Nanocrystals and Graphene
  Upconverting Nanocrystals (UCNCs) are nanometer sized particles with the ability to absorb low energy near infrared photons and emit higher energy photons as near infrared and visible light. In cancer treatment, UCNCs can dually enhance the contrast and selectivity of the imaging of cancer cells in MRI as well as act as carriers for chemotherapy drugs and photosensitizers for Photodynamic Therapy. MnF2 is utilized for it’s quenching tendencies of green emissions and favor of red emissions which is necessary for deep tissue penetration. Optical abosorption in MnF2 is attributed to the d-d transisiton of Mn2+ ions and fluoride contributes to low phonon energy which increases UC efficiency and leads to powerful luminescence. In comparison Yttrium Fluorides have shown to be some of the most efficient host crystals for Upconversion luminescence and demonstrate a rather simple synthesis on the nanometer scale.

Nanoscale, 7, 10101-10110 (2015)
RSC Advances, 4, 61891-61897 (2014) 
Journal of Materials Chemistry C, 2, 1736-1741 (2014)

  upconverting nanocrystal nastaran hashemi    
           
             
             
         

 
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