Hal Holmes

Hal Holmes
Conservation X Labs

Doctor of Philosophy

About

22
Publications
2,072
Reads
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151
Citations
Additional affiliations
September 2014 - present
University of Washington Seattle
Position
  • Research Assistant
September 2009 - April 2014
Michigan Technological University
Position
  • Research Assistant

Publications

Publications (22)
Preprint
Sample preparation in genomics is a critical step that is often overlooked in molecular workflows and impacts the success of downstream genetic applications. This study explores the use of a recently developed focused ultrasound extraction (FUSE) technique to enable the rapid release of DNA from plant tissues for genetic analysis. FUSE generates a...
Article
Full-text available
Objective: Histotripsy is a non-thermal focused ultrasound ablation method that destroys tissue through the generation of a cavitation bubble cloud. Previous work studying intrinsic threshold histotripsy has shown that dense bubble clouds can be formed by a single-cycle pulse when the negative pressure exceeds an intrinsic threshold of ~25-30 MPa,...
Article
Full-text available
Rapid DNA extraction is a critical barrier for routine and fieldable genetics tests for applications in conservation, such as illegal trafficking and fraudulent mislabelling. Here, we develop a non‐thermal focused ultrasound extraction (FUSE) technique that creates a dense cloud of high‐pressure acoustic cavitation bubbles to disintegrate targeted...
Article
Full-text available
The droplet response to vibrations has been well characterized on open substrates, but microfluidic applications for droplets on open systems are limited by rapid evaporation rates and prone to environmental contamination. However, the response of enclosed droplets to vibration is less understood. Here, we investigate the effects of a dual-plate en...
Article
The effect of sub-cellular mechanical loads on the behavior of fibroblasts was investigated using magnetoelastic (ME) materials, a type of material that produces mechanical vibrations when exposed to an external magnetic AC field. The integration of this functionality into implant surfaces could mitigate excessive fibrotic responses to many biomedi...
Article
Full-text available
Anisotropic ratchet conveyors (ARCs) are a recently developed microfluidic platform that transports liquid droplets through a passive, microfabricated surface pattern and applied orthogonal vibrations. In this work, three new functionalities are presented for controlling droplet transport on the ARC system. These devices can pause droplet transport...
Article
An anisotropic ratchet conveyor is an asymmetric, periodic, micropatterned surface that propels droplets when vibrated with a sinusoidal signal at certain frequencies and amplitudes. For each input frequency, there is a threshold amplitude beyond which the droplet starts to move. In this paper, we study the parameters that initiate droplet motion a...
Article
Anisotropic ratchet conveyors (ARC) are a type of digital microfluidic system. Unlike electrowetting based systems, ARCs transport droplets through a passive, micro-patterned surface and applied orthogonal vibrations. The mechanics of droplet transport on ARC devices has yet to be as well characterized and understood as on electrowetting systems. I...
Article
Silica-based materials are being developed and used for a variety of applications in orthopedic tissue engineering. In this work, we characterize the ability of a novel silica sol vapor deposition system to quickly modify biomaterial substrates and modulate surface hydrophobicity, surface topography, and composition. We were able to show that surfa...
Article
Full-text available
This review article examines digital microfluidic systems that manipulate droplets through surface anisotropy. These systems are categorized as surface tension driven or contact line driven. Surface tension driven systems include electrowetting on dielectric, Marangoni flow on microheater arrays, and chemical gradient surfaces, whereas contact line...
Article
Full-text available
Magnetoelastic (ME) materials have many advantages for use as sensors and actuators due to their wireless, passive nature. This paper describes the application of ME materials as biodegradable implants with controllable degradation rates. Experiments have been conducted to show that degradation rates of ME materials are dependent on the material co...
Article
Full-text available
As a prominent concern regarding implantable devices, eliminating the threat of opportunistic bacterial infection represents a significant benefit to both patient health and device function. Current treatment options focus on chemical approaches to negate bacterial adhesion, however, these methods are in some ways limited. The scope of this study w...
Article
An S-nitroso-N-acetylpenicillamine (SNAP) derivatization approach was used to modify existing free primary amines found in fibrin (a natural protein-based biomaterial) to generate a controlled nitric oxide (NO) releasing scaffold material. The duration of the derivatization reaction affects the NO release kinetics, the induction of controlled NO-re...
Article
Full-text available
Nitric oxide (NO) release can promote healthy tissue regeneration. A PEG-fibrinogen adhesive hydrogel that would allow for inducible NO release was created with mechanical properties that could be tailored to specific applications and tissue types. PEG (4-arm)-fibrinogen hydrogels of varying ratios were derivatized with S-nitroso-N-acetyl-D, L-peni...
Article
Silica-based sol-gel and bioglass materials are used in a variety of biomedical applications including the surface modification of orthopedic implants and tissue engineering scaffolds. In this work, a simple system for vapor depositing silica sol-gel nano- and micro-particles onto substrates using nebulizer technology has been developed and charact...
Article
Full-text available
Magnetoelastic (ME) biomaterials are ferromagnetic materials that physically deform when exposed to a magnetic field. This work describes the real-time control and monitoring capabilities of ME biomaterials in wound healing. Studies were conducted to demonstrate the capacity of the materials to monitor changes in protein adsorption and matrix stiff...
Article
Full-text available
A new system was designed to selectively control cellular adhesion to medical implants. The system is based on magnetoelastic (ME) materials that can be remotely set to generate mechanical vibrations at submicron levels with predetermined amplitude and frequency. Previous studies have demonstrated the capacity of these vibrations to control cellula...
Article
Full-text available
K.G.O.) These authors contributed equally to this work. Abstract: This paper describes the functionalization of magnetoelastic (ME) materials with Parylene-C coating to improve the surface reactivity to cellular response. Previous study has demonstrated that vibrating ME materials were capable of modulating cellular adhesion when activated by an ex...
Article
Full-text available
A system was developed for real-time, in vivo investigation of the relationship between local cell-level nano-mechanical perturbation and cell response to chemical-physical biomaterial surface properties. The system consisted of a magnetoelastic (ME) layer that could be remotely set to vibrate, at submicron levels, at a predetermined amplitude and...
Conference Paper
Fibroblastic activity is an innate function of the host response. In the presence of many percutaneous biomedical implants, this activity becomes uncontrollable, resulting in significant fibrous overgrowth at the soft tissue-implant interface [1]. The aberrant cell growth associated with pathological fibrosis can lead to extensive remodeling and ex...

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Projects

Projects (2)
Project
Park rangers, customs officers, and law enforcement agents are at the front-lines of wildlife and timber trafficking issues and need new technologies that provide durable advantages over traffickers. Additionally, supply chain managers and corporate seafood buyers need ways to inspect their supply chain quickly and accurately. To meet this need, we are creating a low-cost, modular, portable DNA barcode scanner, designed for the developing world, that can identify wood, fish, and/or wildlife product samples in the field to the genus and species level without access to taxonomic experts or a laboratory. The device will utilize the Barcode of Life Database (BOLD) as a reference library, and we are creating disposable identification assays which can be used for sample species identification. Such a device will give front-end law enforcement agents and supply chain inspectors the ability to quickly and precisely inspect and ID products, and decide whether further analysis necessary.
Archived project
The development of an automated, portable, DNA barcode device for applications in conservation