No abstract

Therapeutic antibodies (Abs) are a rapidly growing and economically promising biotechnological research area. Therapeutic Ab production typically involves screening large numbers of Ab-secreting cells (ASCs) in order to identify those producing Abs targeting a specific antigen (Ag) with the highest affinity; a process often requiring weeks to complete. We are contributing to a multidisciplinary project focused upon the development of an immunobiosensing array ultimately intended to directly monitor the Ag-specific Ab production by thousands of ASCs on a single slide in real-time. Each ASC shall be microfluidically guided and trapped near a surface plasmon (SP) resonant nanohole array sensor so as to detect the binding of secreted Abs to Ag immobilized onto the sensor’s surface. This paper presents the initial progress of our contribution to this project: the development of polymeric microfluidic devices to guide and trap large ASC populations within arrays of single-cell traps. More specifically, this paper presents several different polymer-based microfluidic trapping devices, based upon perfusive flow-through cell traps and microwells which trap settling cells, which have been evaluated using COMSOL® simulations and tested using microsphere- and cell-based flow experiments. Our initial results are promising, and verify the functionality of our microfluidic cell trap designs.

We present the effect of surface treatments/coatings and soft bake temperatures aimed at improving adhesion and surface uniformity of SU-8 on glass substrates. While the adhesion strength of SU-8 to metal layers on glass and silicon has been previously investigated, our research examines the influence of additional surface treatments (RCA, Acetone/IPA rinse) and coatings (fresh/one-day-aged Ti, fresh/one-day-aged Cr, SU-8 2005®) on adhesion strength as well as surface uniformity for 100 μm thick SU-8 films. Additionally, we vary the soft bake times and temperatures while keeping all other process parameters constant, to correlate adhesion strength with surface uniformity of SU-8 films for each surface modification.We have found that for all surface treatments/coatings, a soft bake temperature of 65 o C for 90 minutes yielded a more uniform SU-8 film (σ = 5.18 μm) as compared to the manufacturer-recommended soft bake temperature of 95 o C (σ = 12.66 μm) for 30 minutes. Consequently, a more uniform SU-8 film provided excellent adhesion strength (> 2 MPa, as determined by stress testing using an Instron® microtester) for both metallic seed layers while the adhesion strength of films baked at 95 o C was determined to be < 0.5 MPa. This study, for the first time, has been able to quantitatively determine the adhesion strength of SU-8 films on different seed layers deposited on glass substrates, for varying soft bake temperatures.