Maxine A. McClain

Microneedle patches: Usability and acceptability for self-vaccination against influenza

While therapeutic drugs are routinely self-administered by patients, there is little precedent for self-vaccination. Convenient self-vaccination may expand vaccination coverage and reduce administration costs. Microneedle patches are in development for many vaccines, but no reports exist on usability or acceptability. We hypothesized that naïve patients could apply patches and that self-administered patches would improve stated intent to receive an influenza vaccine. We conducted a randomized, repeated measures study with 91 venue-recruited adults. To simulate vaccination, subjects received placebo microneedle patches given three times by self-administration and once by the investigator, as well as an intramuscular injection of saline. Seventy participants inserted patches with thumb pressure alone and the remainder used snap-based devices that closed shut at a certain force. Usability was assessed by skin staining and acceptability was measured with an adaptive-choice analysis. The best usability was seen with the snap device, with users inserting a median value of 93-96% of microneedles over three repetitions. When a self-administered microneedle patch was offered, intent to vaccinate increased from 44% to 65% (CI: 55-74%). The majority of those intending vaccination would prefer to self-vaccinate: 64% (CI: 51-75%). There were no serious adverse events associated with use of microneedle patches. The findings from this initial study indicate that microneedle patches for self-vaccination against influenza are usable and may lead to improved vaccination coverage.

Three-Dimensional Metal Transfer Micromolded Microelectrode Arrays (MEAS) for In-Vitro Brain Slice Recordings

We report successful electrical characterization and electrophysiological recordings from hippocampal brain slices using metal transfer micromolded three-dimensional microelectrode arrays (3-D MEAs). These MEAs have been fabricated on polymer substrates using metal transfer micromolding. They have further been packaged on glass substrates and insulated using parylene deposition. Recording sites have been defined using laser micromachining and RIE etching. Initial electrical and electrophysiological characterization of the MEAs has been successfully demonstrated in this paper. We believe this fabrication approach enables manufacturing-friendly batch fabrication of truly disposable, biocompatible and cost-effective MEAs, which will be indispensable to the neurophysiology and pharmacology communities.

Metal-Transfer-Micromolded Three-Dimensional Microelectrode Arrays for in-vitro Brain-Slice Recordings

We report the development of metal-transfer-micromolded 3-D microelectrode arrays (3-D MEAs) and demonstrate successful electrical characterization, biocompatibility measurements, and electrophysiological recordings from rat hippocampal brain slices with these MEAs. Metal transfer micromolding is introduced as a manufacturing technology for producing nonplanar metallized patterned microelectromechanical-systems devices such as MEAs on polymeric substrates. This technology provides a self-aligned metallization scheme that eliminates the need for complex 3-D lithography. Two techniques, i.e., an intentionally formed nonplanar mold and a shadow mask, are demonstrated for the self-aligned metallization scheme. The MEAs have further been packaged using custom-designed commercial printed circuit boards and insulated using parylene deposition. Recording sites have been defined using two techniques: laser micromachining/reactive ion etching (RIE) of parylene and selective deposition of parylene using a “capping” technique. Electrical (impedance spectroscopy), biocompatibility (2-D planar cultures of neurons), electrophysiological (tissue slice recordings) characterizations of the MEAs are successfully demonstrated in this paper. The impedance of the electrodes was modeled based on a classical equivalent circuit, and high-frequency impedance estimation techniques were studied. We believe this fabrication approach offers an attractive route to disposable and biocompatible 3-D MEAs, utilizable by the neurophysiology and pharmacology communities.

Rapid Cellular Assays on Microfabricated Fluidic Devices

Functional elements are being developed to load cells with fluorescent markers, perform cytometry, lyse cells, and separate the lysate contents on a microfluidic device.

Single Cell Lysis on Microfluidic Devices

Methods to rapidly lyse cells are needed for studying biochemical reaction systems in cells with short half-lives such as protein phosphorylation. Chemical and electrical methods, therefore, were examined to rapidly lyse cells on microfabricated fluidic devices. The most effective cell membrane disruption involved a combination of both chemical and electrical lysing techniques.

Microfabricated Fluidic Devices for Cellular Assays

Flow cytometry was demonstrated on a glass microchip fabricated using standard photolithographic techniques. The channel walls were coated to prevent cell adhesion, and the cells were transported electrophoretically by applying potentials to the fluid reservoirs. The sample stream was electrophoretically focused in two dimensions at a cross intersection to enable single cell interrogation. An Escherichia coli sample was labeled on-chip with a membrane permeable nucleic acid stain Syto 15, and coincident light scattering and fluorescence data were obtained from the these labeled cells.