Duy-Vu Pham

A thin-film microprocessor with inkjet print-programmable memory

The Internet of Things is driving extensive efforts to develop intelligent everyday objects. This requires seamless integration of relatively simple electronics, for example through ‘stick-on electronics labels. We believe the future evolution of this technology will be governed by Wrights Law, which was first proposed in 1936 and states that the cost of a product decreases with cumulative production. This implies that a generic electronic device that can be tailored for application-specific requirements during downstream integration would be a cornerstone in the development of the Internet of Things. We present an 8-bit thin-film microprocessor with a write-once, read-many (WORM) instruction generator that can be programmed after manufacture via inkjet printing. The processor combines organic p-type and soluble oxide n-type thin-film transistors in a new flavor of the familiar complementary transistor technology with the potential to be manufactured on a very thin polyimide film, enabling low-cost flexible electronics. It operates at 6.5u2005V and reaches clock frequencies up to 2.1u2005kHz. An instruction set of 16 code lines, each line providing a 9 bit instruction, is defined by means of inkjet printing of conductive silver inks.

Bidirectional communication in an HF hybrid organic/solution-processed metal-oxide RFID tag

The ambition of printing item-level RFID tags is one of the driving forces behind printed electronics research. Organic RFID tags have been shown, initially using p-type organic semiconductors [1-4]. The introduction of n-type organic semiconductors with reasonable performance made organic CMOS conceivable [5] and organic CMOS RFID tags were shown [6]. However, all currently reported organic RFID tags are based on a tag-talks-first principle: as soon as the tag gets powered from the RF field, its code is transmitted at a data rate determined by an internal ring oscillator. Practical RFID systems will need to be able to read multiple RFID tags within the reach of the reader antenna. Existing anti-collision protocols implemented in organic RFID tags [2,4] are limited to about maximum 4 tags and come at the cost of a slow reading time. In this paper, we for the first time realize a reader-talks-first low-temperature thin-film transistor (TFT) RFID circuit. We use a complementary hybrid organic/oxide technology. As organic transistors with reasonable channel lengths (≥2μm) have a cut-off frequency below 13.56MHz, the base carrier frequency of HF communication, present technologies on foil do not yet allow to extract the circuit clock as a fraction of the base carrier. We solve this by introducing an original uplink (reader-to-tag) scheme, in which a slow clock (compatible with our transistors speed) is transmitted as amplitude-modulation on the base carrier while data is encoded on this clock by pulse width modulation (PWM).

30.1 8b Thin-film microprocessor using a hybrid oxide-organic complementary technology with inkjet-printed P 2 ROM memory

We present an 8b general-purpose microprocessor realized in a hybrid oxide-organic complementary thin-film technology. The n-type transistors are based on a solution-processed n-type metal-oxide semiconductor, and the p-type transistors use an organic semiconductor. As compared to previous work utilizing unipolar logic gates [1], the higher mobility n-type semiconductor and the use of complementary logic allow for a >50x speed improvement. It also adds robustness to the design, which allowed for a more complex and complete standard cell library. The microprocessor consists of two parts, a processor core chip and an instruction generator. The instructions are stored in a Write-Once-Read-Many (WORM) memory formatted by a post-fabrication inkjet printing step, called Print-Programmable Read-Only Memory (P2ROM). The entire processing was performed at temperatures compatible with plastic foil substrates, i.e., at or below 250°C [2].

Bidirectional Communication in an HF Hybrid Organic/Solution-Processed Metal-Oxide RFID Tag

A bidirectional communication protocol allows radio-frequency identification (RFID) tags to have readout of multiple tags in the RF field without collision of data. In this paper, we realized bidirectional communication between a reader system and thin-film RFID tag by introducing a novel protocol for the uplink communication. Amplitude modulation on the 13.56-MHz base carrier is used to transmit the uplink clock, whereas the data is modulated by varying pulsewidths on this clock. The technology for the thin-film RFID tags combines metal-oxide n-type transistors with organic p-type transistors resulting in a hybrid complementary technology flow. The design of the RFID tag comprises of two metal-oxide transistor rectifiers and a comparator to decode the data transmitted by the reader and different code generators that send 8 bits or 96 bits to the reader.