Paper
6 matches found.


A wearable paper based perspiration monitoring platform with passive and active visual indicators

paper, microfluidics, sensor, laser treatment

Hydration in humans is a delicate parameter. Even small deviations such as 2 percent from normal levels can affect a person’s cognitive and physical performance by more than 30 percent.Conventional methods for monitoring hydration are either invasive, require non-portable equipment or do not yield results immediately. Feedback from many experts including marathon directors, the Ironman World Championship, Olympic triathlon athletes and many collegiate and professional coaches, athletes, race directors and EMTs, followed by intensive product development in the lab has resulted in the prototype of a palm-size patch consists of filter paper that is laser-machined to create a radial array of strips, which are laminated with a water-impermeable film to form micro-channels. The channels are loaded with a water-activated dye at one end. As sweat secretion increases, the strips are activated sequentially, changing from blue to red and providing easily identifiable levels of moisture loss.

Publications

A Paper-Based Oxygen Generation and Sensing Platform

Bioflex - Chronic wound management - Parchment paper - Hydrogen peroxide - Manganese dioxide

A flexible, parchment paper/PDMS based platform for local wound oxygenation is fabricated and characterized. The platform consists of a PDMS microfluidic network bonded to a parchment paper substrate. Generation of oxygen occurs by flowing H2O2 through the channels and chemically decomposing it via a catalyst embedded in laser-defined regions of the parchment paper. PDMS is bonded to parchment paper using partially cured PDMS followed by a brief air plasma treatment, resulting in a strong bond. For pressures below 110 Torr the parchment paper is observed to be impermeable to water and hydrogen peroxide. The oxygen permeability of parchment paper is measured to be 1.42 μL/(Torr mm2 min). Using a peroxide flow rate of 250 μL/min, oxygen generation in the catalyst spots raises the oxygen level on the opposite side of the parchment paper from atmospheric levels (21%) to 25.6%, with a long-term (30 h) generation rate of 0.1 μL O2/min/mm2. This rate is comparable to clinically proven levels for adequate healing. Device and material in vitro biocompatibility is confirmed with NIH 3T3 fibroblast cells via alamar blue assays.

Publications

Flexible/stretchable pH Sensor Array

Keywords: pH sensor sensor array paper

The pH level in a chronic wound bed is a key indicative parameter for assessment of the healing progress. Due to fragility and inability to measure multiple wound regions simultaneously, commercial glass microelectrodes are not well-suited for spatial mapping of the wound pH. To address this issue, we present an inexpensive flexible array of pH sensors fabricated on a polymer-coated commercial paper (palette paper). Each sensor consists of two screen-printed electrodes, an Ag/AgCl reference electrode and a carbon electrode coated with a conductive proton-selective polymeric (polyaniline, PANI) membrane. Laser-machining is used to create a self-aligned passivation layer with access holes that is bonded over the sensing and reference electrodes by lamination technology. Characterization of the pH sensors reveal a linear (r2 = 0.9734) relationship between the output voltage and pH in the 4�?0 pH range with an average sensitivity of �?0 mV/pH. The sensors feature a rise and fall time of 12 and 36 s for a pH swing of 8-6-8. The sensor biocompatibility is confirmed with human kertinocyte cells.

Publications

Paper-based electrochemical power source

Disposable - Water-activated - paper substrate

An inexpensive, rapid and simple method to fabricate flexible zinc-copper electrochemical batteries on a hydrophobic (wax) paper through laser-assisted patterning of metal tapes and salt-impregnated filter papers, with lamination employed for packaging. Experiment results showed that a 3-cell battery lit a green LED (1.70 V) for half an hour and achieved a power density of 0.22 mW/cm2.

Publication

Laser-treated hydrophobic paper: an inexpensive microfluidic platform

G. Chitnis, Z. Ding, C.L. Chang, C.A. Savran, B. Ziaie

We report a method for fabricating inexpensive microfluidic platforms on paper using laser treatment. Any paper with a hydrophobic surface coating (e.g., parchment paper, wax paper, palette paper) can be used for this purpose. We were able to selectively modify the surface structure and property (hydrophobic to hydrophilic) of several such papers using a CO2 laser. We created patterns down to a minimum feature size of 62 ± 1 µm. The modified surface exhibited a highly porous structure which helped to trap/localize chemical and biological aqueous reagents for analysis. The treated surfaces were stable over time and were used to self-assemble arrays of aqueous droplets. Furthermore, we selectively deposited silica microparticles on patterned areas to allow lateral diffusion from one end of a channel to the other. Finally, we demonstrated the applicability of this platform to perform chemical reactions using luminol-based hemoglobin detection.

Publications