All-printed organic photodiode arrays on plastic are reported with average specific detectivities of 3.45 × 10(13) cm Hz(0.5) W(-1) at a bias of -5 V. The blade-coated polyethylenimine cathode interlayer and active layer, and screen-printed anode enable precise device performance tunability and excellent homogeneity at centimetric scales. These devices' high operational reverse bias, good linear dynamic range, and bias stress stability make them attractive for implementation in imaging systems.
Purpose
To develop methods for characterizing materials used in screen-printed MRI coils and improve SNR with new lower-loss materials.
Methods
An experimental apparatus is created to characterize dielectric properties of plastic substrates used in receive coils. Coils are fabricated by screen printing conductive ink onto several plastic substrates. Unloaded and sample loaded quality factor (QUnloaded/QLoaded) measurements and scans on a 3T scanner are used to characterize coil performance. An experimental method is developed to describe the relationship between a coil's QUnloaded and the SNR it provides in images of a phantom. Additionally, 3T scans of a phantom and the head of a volunteer are obtained with a proof-of-concept printed 8-channel array and the results are compared to a commercial 12-channel array.
Results
Printed coils with optimized substrates can exhibit up to 97% of the image SNR when compared to a traditional coil on a loading phantom. QUnloaded and the SNR of coils are successfully correlated. The printed array results in images comparable to the quality given by the commercial array.
Conclusion
With the methods and materials proposed, the SNR of printed coils approaches that of commercial coils while using a new fabrication technique that provides more flexibility and close contact to the patient's body.
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