Technology

Passive sensor

Overview of lab-scalable electrode fabrication

Digital design : Schematic of CO2 laser cutting of Kapton/Au electrodes.

PEDOT:PSS coating on the patterned Kapton/Au electrodes.

We consider two types of sensors. We realize organic electrodes created by coating with the bio compatible polymer PEDOT:PSS, which improve impedance and flexibility of the sensors.

Active sensor

We also develop active sensors using organic electrochemical transistors (OECTs) where the potential difference on the human body serves as the potential of the gate electrode. Active sensors directly amplify the electrophysiological data with current read in the transistor channel.

Sensor

OECT Scheme

Flexible OECT

The active sensors are fabricated on polyimide so that they can easily integrate with other BAYFLEX technology.

Measurements

Test measurements comparing electrocardiograms of the standard Ag/AgCl electrodes with active OECT electrodes.

OTFTs for processing data

The development of the organic thin film transistors (OTFTs) consists of two technologies. First, we use an already established technology of pOTFTs and low K dielectric (left), called GEN1, to prototype the first circuits. Second (right), we develop a high K dielectric technology (GEN2) that enables operation at lower threshold voltages to realize low power devices.

OTFT

Cross View Gen 1

Cross View Gen 2

BAYFLEX circuits in GEN1 OTFT technology

GEN2 transistors with low threshold voltage

OECTs for classification

OECT

Challenges

The challenge in developing the organic electrochemical transistors for the classification task is to be able to adjust the threshold voltage for low power operation and for cascading devices. To this end, we have worked on shifting the threshold voltage of PEDOT:PSS transistors using UV light.

Classification design

We have also developed OECT processes to realize complementary inverters, which are key elements in our classification design.

Results

We have successfully developed a method for integrating the 3 technologies just discussed, details will be posted soon.