Living matter undergoes physical (sometimes lethal) damage to their DNA when exposed to the ionizing radiation. If such physiochemical alterations to the DNA can be utilized to measure the absorbed dosage, it can provide an invaluable information regarding the biological damage to the organism. One particular organism that can serve such purpose (radiation surrogate) is the yeast, a eukaryotic microorganism with wide and ancient commercial applications in food and beverage industry. Yeast is a well-studied microorganism having homologous genetic sequence to humans. Based on this noble idea, the low-cost, wearable, film-type radiation sensor is developed that utilizes yeast as the sensing material, hence, producing an output that can be directly correlated to the DNA damage and cellular inactivation/death. Our impedance-based sensor output is a function of fermentation byproducts (i.e., generated CO2 and resulting dissolved carbonic acid) of the surviving yeast (S. cerevisiae) after exposure to the ionizing radiation. A prototype sensor with dimensions of 18×18mm2 shows a maximum sensitivity of 0.154 Ω/Ω0decade-rad.Publications
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
Piezoelectric receiver feeds AC signal to a full-wave rectifying circuit to create a constant DC voltage for electrolysis.
The electrolytically-generated gas pressure will be accumulated for pumping the drug out.
Flow rate of 0.1 μL/s with a backpressure of 24.2 Torr.
Once activated through a magnetic proximity fuse, the capsule opens up and releases its powdered payload in a location specified by an implanted miniature magnetic marker or an externally-worn larger magnet. The capsule (9 mm × 26 mm) comprises of two compartments; one contains a charged capacitor and a reed switch while the second one houses the drug reservoir capped by a taut nylon thread intertwined with a nichrome wire. The nichrome wire is connected to the capacitor through the reed switch. The capacitor is charged to 2.7V before ingestion and once within the proximity of the permanent magnet; the reed switch closes, discharging the capacitor through the nichrome wire, melting the nylon thread, detaching the cap and emptying the drug reservoir.Multimedia Publications
The invented diaper-embedded system is comprised of a flexible urine-activated paper battery, a colorimetric detection unit (LED/strip/photodiode), associated circuitry, wireless transmitter, and metallic traces integrated on a hydrophobic flexible substrate. It provides a fully autonomous (stays dormant before urination) and wireless monitoring of UTI upon the urination, which does not require any operation/intervention from the patient/caregiver. The entire detection and data transmission process completes within 30 minute from the beginning of the urination.Project website Publications