Paul K. Jo

3-D Integrated Electronic Microplate Platform for Low-Cost Repeatable Biosensing Applications

This paper presents a 3-D integrated disposable “electronic microplate” (e-microplate) platform that allows the reuse of CMOS biosensor, thereby significantly reducing cost and increasing throughput compared to nondisposable biosensing systems. The e-microplate utilizes mechanically flexible interconnects and through-silicon-vias to electrically connect the cells cultured on the top (sensing electrode side) of the e-microplate to the electrodes on the CMOS biosensor while maintaining a physical separation between the aforementioned substrate tiers. Electrical measurements performed show that the incorporation of the e-microplate does not degrade the sensing amplifiers gain, 3-dB bandwidth, or the input referred noise; this ensures a high signal-to-noise ratio allowing accurate sensing of weak signals from living cells under test. Cell growth experiments performed show adhesion and growth of mouse embryonic stem cells on the surface of the sensing electrodes of the e-microplate. Impedance mapping for Dulbeccos phosphate buffered saline solution performed with the e-microplate, for two different e-microplate assemblies, confirms the functional accuracy of the assembled systems.

Monolithic-like heterogeneously integrated microsystems using dense low-loss interconnects

In this paper, two integration technologies are discussed for heterogeneously integrated microsystems. First, this paper presents low-loss TSVs using an air-isolation technique for silicon interposers. The proposed air-isolated TSVs exhibit approximately 35% and 37% reduction in insertion loss and capacitance, respectively, at 20 GHz. Moreover, this paper presents a TSV-less integration technology using bridge chips and Compressible MicroInterconnects (CMIs). Compared to other packaging and assembly options, the investigated TSV-less approach provides monolithic-like electrical performance by significantly reducing chip-to-chip interconnect length and loss, increasing interconnect density, and providing the ability to seamlessly integrate chips of diverse functionalities.

Dense and Highly Elastic Compressible MicroInterconnects (CMIs) for Electronic Microsystems

In this paper, dense, highly elastic compressible microinterconnects (CMIs) are presented as an enabling technology for next generation sockets, probe cards and heterogeneous integrated systems. Free-standing CMIs with 75 µm height are fabricated using a thick sacrificial photoresist layer with an upward curved sidewall profile. The CMIs show a 45 µm vertical elastic range of motion. The fabricated CMIs have an in-line pitch of 150 µm, mechanical compliance of 9.2 mm/N, and vertical elastic motion of up to 5,000 indentation cycles. The smallest in-line pitch of CMIs demonstrated is 40 µm. The average post-assembly resistance of the CMIs, including the contact resistance, was measured to be 176.3 mΩ.