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Advances in additive manufacturing have enabled development of printable electronic sensor elements that can be deposited onto flexible substrates. To benchmark performance of printed sensors against the state of the art, NASA developed a low power flexible sensor platform. The platform integrates the following key components and features: -Flexible substrate: DuPont Kapton allows bending around cylindrical surfaces as small as in diameter. -Embedded microcontroller: Cypress CY8C4248 LQI-BL583 Arm Cortex M0 processor with BLE wireless controller, max frequency 48 MHz. Supports low power modes of operation, capacitive sensing support, and a single-channel 12-bit AD converter. -Commercial sensor suite: Bosch BNO080 inertial sensor; Bosch BME280 humidity, pressure, and temperature sensor; AMS CCS811 air quality sensor (VOCs and CO2). -Prototyping area for custom-printed sensors: 1) thermistor, uses carbon-based PTC resistor paste DuPont2792; 2) capacitive humidity sensor using a NASA-developed dielectric ink. NASA researchers have used the platform to study performance of the printed capacitive humidity sensor. The 2x4 mm co-doped barium titanate sensing element is highly sensitive to water vapor and performs as an unobtrusive breathing monitor, sensitive to breath at distances of up to 20 cm. Average change of sensor capacitance at a distance of 7.5 cm was observed to be 6.23.5 pF.

With a form factor close to a deck of playing cards, the system interrogator has custom software to interface with and service a population of sensor tags at the required data rates. Each EPCglobal C1G2 sensor tag uses incident interrogator energy to charge its small integrated circuit (IC), which reads an internal memory bank, encodes identification data, and uses that information to modulate and backscatter a reply to the interrogator using reflected interrogator energy. Two tag interfaces allow the attached processor to power the reading/writing of data to the tag memory and then allows the interrogator to power the reading of the tag memory data. When neither of the two interfaces are engaged, the RFID IC is completely powered down. Reading and writing tag memory consumes relatively little power compared to the power draw of active transmitter/receiver protocols like Bluetooth, Zigbee, and Wi-Fi. Compared to passive sensing protocols, this wireless instrumentation system enables sampling of a larger population of tags without the computational burden associated with surface acoustic wave (SAW) sensing. RFID-Enabled Wireless Instrumentation technology allows the RFID interrogator to write data through the interface of a sensor tag memory bank using only interrogator power. With only minimal cost to the sensors power budget, the microcontroller unit can read that data out over the serial interface. The sensor can transmit and receive data at no effective cost to its small coin cell battery power supply. This technology is readiness level (TRL) 8 (actual system completed and "flight qualified" through test and demonstration) and the innovation is now available for your company to license. Please note that NASA does not manufacture products itself for commercial sale.