Publications

Microfabrication techniques were developed to create flexible 24 um thick glucose sensors on polyimide substrates. Measurements of the sensor performance, recorded as voltage potential, were carried out for a range of glucose concentrations (0 – 8 mM) in physiological saline (0.1 M NaCl, pH 7.4). The sensors show rapid response times (seconds to stable potential) and good sensitivity in the 0 – 4 mM range. Additionally, we demonstrate that the sensors can operate as fuel cells, generating peak power levels up to 0.94 uW/cm2. Such flexible devices, which can be rolled up to increase surface area within a fixed volume, may enable ultra-low-power bio-electronic implants for glucose sensing or glucose energy harvesting in the future.

MACOM designed the initial radar panels for the next generation surveillance radar with limited funds, with the philosophy that the initial design would be kept as simple as possible and that incremental improvements would be made as the program progressed, with the intent of having a tile assembly that is easy to manufacture by the first build of a larger radar (approximately 80 panels). The design is now being updated for an 80 panel order with the goal of optimizing the design electrically, for assembly and for test. This paper will discuss both the design, assembly, packaging, and test updates that are being made to have a board and board assembly that is easy to manufacture and test, with the goal of keeping cost as low as possible. These techniques will not only be used for the MPAR tiles, but also for tiles that are currently being developed for other programs.

Inductance of superconducting thin-film inductors and structures with linewidth down to 250 nm has been experimentally evaluated. The inductors include various striplines and microstrips, their 90 degree bends and meanders, interlayer vias, etc., typically used in superconducting digital circuits. The circuits have been fabricated by a fully planarized process with 8 niobium layers, developed at MIT Lincoln Laboratory for very-large-scale superconducting integrated circuits. Excellent run-to-run reproducibility and inductance uniformity of better than 1% across 200-mm wafers have been found. It has been found that the inductance per unit length of stripline and microstrip line inductors continues to grow as the inductor linewidth is reduced deep into the submicron range to the widths comparable to the film thickness and magnetic field penetration depth. It is shown that the linewidth reduction does not lead to widening of the parameter spread due to diminishing sensitivity of the inductance to the linewidth and dielectric thickness. The experimental results were compared with numeric inductance extraction using commercial software and freeware, and a good agreement was found for 3-D inductance extractors. Methods of further miniaturization of circuit inductors for achieving circuit densities >10^6 Josephson junctions per cm^2 are discussed.

Graphene transistors are made by transferring a thin graphene film grown on Ni onto an insulating SiO2 substrate. The properties and integration of these graphene-on-insulator transistors are presented and compared to the characteristics of devices made from graphitized SiC and exfoliated graphene flakes.