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J.C. Lesho, B.M. Romenesko and A.F. Hogrefe
JHU/APL has developed and tested ingestible pills that telemeter core body temperature. The hybrids were manufactured as chip and wire on thick film ceramic substrates and…
JHU/APL has developed and tested ingestible pills that telemeter core body temperature. The hybrids were manufactured as chip and wire on thick film ceramic substrates and surface mount on polyimide boards. The devices have potential applications for divers, astronauts, soldiers in combat, people working in hazardous conditions and people with hypothermia and hyperthermia. Descriptions of both circuit operation and packaging techniques are included.
Mariam Mir, Murtaza Najabat Ali, Umar Ansari, Patrick J. Smith, Amber Zahoor, Faisal Qayyum and Sabtain Abbas
The fabrication and characterization of a hydrogel-based conductometric sensor have been carried out. The purpose of this research is to fabricate a small robust…
The fabrication and characterization of a hydrogel-based conductometric sensor have been carried out. The purpose of this research is to fabricate a small robust hydrogel-based conductometric sensor for real-time monitoring of pH in the physiological range.
A pH-responsive Chitosan/Gelatin composite hydrogel has been used for this purpose. This study reports and analyzes the sensing response obtained from four hydrogel compositions with varying Chitosan/Gelatin ratios. The pH-responsive nature of the hydrogel has been mapped out through volumetric and conductometric tests. An attempt has been made to correlate these characteristics with the physico-chemical nature of the hydrogel through scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction techniques.
The four hydrogel compositions differed on the basis of gel composition ratios; the conductometric analysis results prove that the sensor with the hydrogel composition (Chitosan 2 per cent, Gelatin 7 per cent, ratio 1:2) produces the best pH resolution in the pH range of 4 to 9. The sensing mechanisms and the differences obtained between individual sensor outputs have been discussed in detail. On the basis of this extensive in vitro assessment, it has been concluded that while key pendant functional groups contribute to pH-responsive characteristics of the hydrogel, the overall sensitivity of the sensors gel component to surrounding pH is also determined by the crystalline to amorphous ratio of the hydrogel composite, its interpenetrating cross-linked structure and the relative ratio of the hydrophilic to the pH-sensitive components.
The conductometric sensor results prove that the fabricated sensor with the shortlisted hydrogel composition shows good sensitivity in the physiological pH range (4 to 9) and it has the potential for use in point of care medical devices for diagnostic purposes.
This is the first reported version of the fabrication and testing and analysis/comparison of a hydrogel-based conductometric sensor based on this composition. The work is original and has not been replicated anywhere.