Extreme temperature semiconductor integrated circuits (ICs) are being developed for use in the hot sections of aircraft engines and other harsh‐environment applications well above the 300 °C effective limit of silicon‐on‐insulator IC technology. This paper reviews progress by the NASA Glenn Research Center and Case Western Reserve University (CWRU) in the development of extreme temperature (up to 500 °C) integrated circuit technology based on epitaxial 6H‐SiC junction field effect transistors (JFETs). Simple analog amplifier and digital logic gate ICs fabricated and packaged by NASA have now demonstrated thousands of hours of continuous 500 °C operation in oxidizing air atmosphere with minimal changes in relevant electrical parameters. Design, modeling, and characterization of transistors and circuits at temperatures from 24 °C to 500 °C are also described. CWRU designs for improved extreme temperature SiC JFET differential amplifier circuits are demonstrated. Areas for further technology maturation, needed prior to beneficial system insertion, are discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

This letter describes the design, fabrication, and testing of a wireless bladder-pressure-sensing system for chronic, point-of-care applications, such as urodynamics or closed-loop neuromodulation. The system consists of a miniature implantable device and an external RF receiver and wireless battery charger. The implant is small enough to be cystoscopically implanted within the bladder wall, where it is securely held and shielded from the urine stream. The implant consists of a custom application-specific integrated circuit (ASIC), a pressure transducer, a rechargeable battery, and wireless telemetry and recharging antennas. The ASIC includes instrumentation, wireless transmission, and power-management circuitry, and on an average draws less than 9 μA from the 3.6-V battery. The battery charge can be wirelessly replenished with daily 6-h recharge periods that can occur during the periods of sleep. Acute in vivo evaluation of the pressure-sensing system in canine models has demonstrated that the system can accurately capture lumen pressure from a submucosal implant location.

The wireless implantable/intracavity micromanometer (WIMM) system was designed to fulfill the unmet need for a chronic bladder pressure sensing device in urological fields such as urodynamics for diagnosis and neuromodulation for bladder control. Neuromodulation in particular would benefit from a wireless bladder pressure sensor which could provide real-time pressure feedback to an implanted stimulator, resulting in greater bladder capacity while using less power. The WIMM uses custom integrated circuitry, a MEMS transducer, and a wireless antenna to transmit pressure telemetry at a rate of 10 Hz. Aggressive power management techniques yield an average current draw of 9 A from a 3.6-Volt micro-battery, which minimizes the implant size. Automatic pressure offset cancellation circuits maximize the sensing dynamic range to account for drifting pressure offset due to environmental factors, and a custom telemetry protocol allows transmission with minimum overhead. Wireless operation of the WIMM has demonstrated that the external receiver can receive the telemetry packets, and the low power consumption allows for at least 24 hours of operation with a 4-hour wireless recharge session.

A trehalose/oxygen biofuel cell was implanted in Blaberus discoidalis to convert chemical energy stored within the insect hemolymph into electrical energy which was then used to power a custom-designed oscillator mounted on the back of the insect, capable of producing signals in the audible range. The ability of this cyborg to generate and transmit signals wirelessly was demonstrated by placing an external receiver up to a few centimeters away from the insect while it was tethered to a device that enabled it to walk in place on top of a light weight, air-suspended solid sphere. Wireless communication could also be established between the transmitter powered by the same type of biofuel cell implanted in the moth Manduca sexta and the receiver, while the live insect was being restrained with wax in a Petri dish. Possible means of reducing the weight and size of the transmitter so as to allow the moth to carry it in flight are discussed. Biofuel cells1,2 have emerged as promising devices for converting chemical into electrical energy in living organisms with potential application in a variety of areas of fundamental and technical relevance.1-6 Efforts in our laboratories have focused on the development of biofuel cells that could be implanted into insects 6 and provide the power required not only for the operation of electronics for sensing, information storage and wireless communication, but also for the stimulation of the nervous system, a strategy that will ultimately allow control of certain aspects of the insect behavior. An attractive feature of this approach is that it provides a continuous and autonomous source of power thereby avoiding the need for an external battery as implemented recently by Bozkurt et al., 7 who succeeded in controlling wirelessly the path of motion of a different species of cockroach Gromphadorhina portentosa. To this end, we designed, constructed and successfully tested an implantable biofuel cell incorporating a bienzymatic anode capable of dissociating trehalose, 8 a dissacharide found in very high concentrations, up to tens of mM, in the hemolymph of insects, 9 to yield glucose, which is then oxidized to gluconolactone by the enzyme glucose oxidase. As shown recently in our laboratories, this type of biofuel cell can generate up to 15.6 μW/cm 2 when implanted in a live cockroach Blaberus discoidalis.6 This contribution represents an extension of our earlier studies and is aimed at demonstrating that a single biofuel cell implanted in the insect can power a judiciously designed electronic oscillator mounted on the insect capable of sending wirelessly signals that can be captured by an external receiver, while the insect, tethered to a fixed structure, is allowed to walk on an air-suspended Styrofoam sphere. ExperimentalElectrochemistry.-Enzyme-modified electrodes were prepared by depositing either a mixture of glucose oxidase (Aspergillus niger, EC 1. pressed and purified in our laboratory), PVI-(dmbpy) 2 Cl 2 (10 mg/mL), and PEGDGE (2.5 mg/mL) (Polysciences, Inc.) where PVI denot...

A family of fully-integrated differential amplifiers was designed and fabricated in 6H-SiC, n-channel JFET integrated-circuit technology. A single-stage amplifier with resistor loads has gain-bandwidth of ~2.8 MHz, and differentialmode gain that varies by less than 1 dB from 25-600 o C. A twostage amplifier with current-source loads and common-mode feedback in 1 st -stage, and resistor loads in 2 nd -stage has gainbandwidth of 1.4 MHz, and differential-mode gain of 69 dB at 576 o C, with just 3.6 dB gain-variation from 25-576 o C.