Carbonized Polymer for Joule Heating Processing Towards Biosensor Development.

This paper presents the experimental findings towards developing carbonized microelectrodes using a Joule heating process within a temperature window that is compatible with CMOS. Bridge-on-pillars polymer structures have been 3D-printed using two-photon polymerization (2PP). They have been annealed in various processing conditions to increase the fraction of carbon in the precursor material and to achieve appreciable electric conductivity so that they can be used to drive current to enable Joule heating. To evaluate the outcome of the processing sequences, Raman spectroscopy has been performed to assess the degree of carbonization. Such CMOS-compatible carbon electrodes are important for monolithic, low-cost biosensor development.Clinical relevance- This establishes the potential of carbonized polymer electrode for low-cost, CMOS-compatible monolithic biosensor platform for implementation in medical diagnosis and treatment.

A Wearable CMOS Impedance to Frequency Sensing System for Non-Invasive Impedance Measurements.

In this paper, we demonstrate a novel non-invasive, wearable impedance sensor. The impedance sensor, using an impedance to frequency measurement, with two modes of resistance and capacitance measurement is implemented in CMOS 130 nm technology. The sensor consisting of current and voltage comparators for different mode of measurement, has a low power consumption of 30 µW per channel. The sensor is demonstrated in two applications, thoracic impedance and hand gesture recognition. Thoracic impedance is based on impedance modulation through fluid accumulation. Hand gestures are detected through tissue impedance sensing. The full thoracic impedance sensing system is smaller than a credit card, low cost, and consumes 3 mW which includes the sensor, transmitter, and power control unit. Data received by this sensor can be easily transferred for further processing and, eventually, detection of heart failure. The electrodes were implemented using conductive paint, and the system was validated using passive loads to represent human tissue models and test subjects. The hand gesture system operates on 600  µW with the maximum number of electrodes, and uses adhesive copper with electrical paint as electrodes.