Efficient Optical Readout: Highly Versatile Chemical Sensor

• Simple design
• Large and versatile detectors possible
• No complex wiring for multiple sensing elements
• Compact architecture with sensing elements directly located on an LED
• Scalable to different sizes and numbers of sensing elements
• Adaptable for aqueous analytes

• Detection of chemical compositions
• Detection of air pollution or toxic trace gases
• Quality assurance

Detailed analysis of analytes in gaseous samples is of great interest both for scientific but also civil applications. State-of-the-art sensors are based on changing electrical properties, e.g., the resistance, of different materials when they are in contact with investigated chemicals. However, it is difficult to construct larger sensors with multiple different sensing elements as each of them requires an individual readout circuit hence drastically increasing the sensor’s complexity. Approaches to observe changing optical properties within the sensing elements have been regarded in the past but are problematic as they typically use up the detector material, hence having a strongly reduced lifetime.

A novel sensor concept has been developed to overcome the aforementioned shortcoming combining the advantageous of both an electrical and optical readout system.
Different sensing materials cause different electrical signals that must be monitored for multiple pixels when exposed to a mixture of analytes. By using the individual electrical signals of each sensing element as an input to an individual optical device, e.g., an LED, they are converted into optical signals. It is thereby much easier to detect optical signals from a large array of chemical pixels, as a single imaging device can acquire data simultaneously from all sensing elements. LEDs are thus highly advantageous as they can be directly implemented into a small-scale sensing element.
Figures 2 a) and b) visualize the simple layout of a chemical sensor as a possible implementation according to the invention. Sensing elements are connected to the common voltage supply and via the LED to the common grounding. A transparent substrate allows for the optical signals to be transmitted to a common imaging device (not shown).
An optical image of the sensor contains the response of the entire sensor array to the exposure with chemical analytes. This image can be evaluated using computational methods like machine learning.

PCT (Application filed)