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Laser experiments, such as those planned at the National Ignition Facility (NIF) and the Omega facility, use small targets with the goal of studying high-energy density physics and inertial confinement fusion. One particular application is a target with layers whose density changes in a carefully designed gradient (from 0.2 to 1.2 g/cm 3 ) for use in isentropic compression experiments (ICE). We are nondestructively determining the density of these layers using two X-ray microscopes. Because of the many interfaces that comprise the layers, a plethora of X-ray phase contrast fringes appear in the images, leading to many radiographic and tomographic artifacts which compromise the ability to infer the density of the layer. In this paper, we describe how we are attacking this problem with a variety of radiographic standards and through radiographic simulation using the HADES radiographic simulation code.

In recently developed laser-driven shockless compression experiments an ablatively driven shock in a primary target is transformed into a ramp compression wave in a secondary target via unloading followed by stagnation across an intermediate vacuum gap. Current limitations on the achievable peak longitudinal stresses are limited by the ability of shaping the temporal profile of the ramp compression pulse. We report on new techniques using graded density reservoirs for shaping the loading profile and extending these techniques to high peak pressures.

The molecular rectifier consisting of protein heterolayer is investigated in molecular-scale for the construction of bioelectronic device. Cytochrome c and green fluorescence protein were used as an electron acceptor and a sensitizer in the molecular layer by mimicking the bacterial photosynthesis. Self-assembled monolayer of thiol-modified cytochrome c was formed on Au coated glass, and then green fluorescence protein was adsorbed onto the cytochrome c surface by electrostatic attraction. The formation of cytochrome c layer onto the Au substrate and green fluorescence protein adsorption onto the cytochrome c layer were observed by the surface plasmon resonance measurement. The surface of heterolayer was observed and analyzed by the scanning tunneling microscopy. The rectifying property of proposed heterolayer was achieved by the scanning tunneling spectroscopy based current–voltage measurement. Finally, the molecular rectifying property was verified.

The self-assembly layer consisting of fusion protein is investigated in molecular-scale for the construction of bioelectronic device. Cytochrome b562 and green fluorescent protein were used as an electron acceptor and a sensitizer in the molecular layer by mimicking the photosynthesis. Self-assembled monolayer of fusion protein was formed on Au coated glass. The formation of fusion protein layer onto the Au substrate was observed by the surface plasmon resonance measurement. The surface of fusion protein layer was observed and analyzed by the scanning tunneling microscopy observation. For embodiment of the molecular electronic device, molecular arrays of fusion protein SA layer were formed by micro contact printing. Surface charge distribution of fusion protein SA layer was measured to confirm an electrical conductivity by electrostatic force microscopy observation.

Biodevices composed of biomolecular layer have been developed in various fields such as medical diagnosis, pharmaceutical screening, electronic device, photonic device, environmental pollution detection device, and etc. The biomolecules such as protein, DNA and pigment, and cells have been used to construct the biodevices such as biomolecular diode, biostorage device, bioelectroluminescence device, protein chip, DNA chip, and cell chip. Substantial interest has focused upon thin film fabrication or the formation of biomaterials mono- or multi-layers on the solid surfaces to construct the biodevices. Based on the development of nanotechnology, nanoscale fabrication technology for biofilm has been emerged and applied to biodevices due to the various advantages such as high density immobilization and orientation control of immobilized biomolecules. This review described the nanoscale fabrication of biomolecular film and its application to bioelectronic devices and biochips.

The transient photocurrent response of biodevice consisting of chlorophyll a Langmuir-Blodgett film was investigated. Chlorophyll a LB films were deposited onto the ITO coated glass. To confirm the film formation, surface analysis of chlorophyll a LB film was done by the measurement of scanning tunneling microscopy. Metal/insulator/metal structured biodevice was constructed by depositing aluminum onto the chlorophyll a LB film surface. To investigate the photoelectric response, action spectrum was measured at various wavelengths. The transient photocurrent characteristic was measured at various wavelengths by xenon lamp irradiation. Finally, the photoinduced charge transfer rates were measured using the transient photocurrent decay times. The proposed biodevice consisting of chlorophyll a could be applied to construct the molecular photonic device due to the photoinduced current flow.

The optimal deposition condition of chlorophyll a (Chl a ) Langmuir–Blodgett (LB) film were investigated based on π – a isotherms, absorption spectrum and scanning tunneling microscopy (STM) observation. The π – a isotherms of Chl a LB film at various air temperatures and subphase pHs were obtained. Optimum temperature and pH for dense packing of Chl a LB layers are 25 °C and 7.0, respectively. The formation of J- and H-aggregations of the ordered chlorophyll a molecules was confirmed by absorption spectrum measurements. The well-ordered structure of Chl a LB layer was observed by STM. Thus, the densely packed Chl a LB layer could be fabricated by the proposed optimal deposition condition.

A ferredoxin adsorbed hetero-self-assembled layer was fabricated by electrostatic attraction. 11-Mercaptoundecanoic acid (11-MUA) was deposited onto Au substrate and then poly- l -lysin (PL) was adsorbed on 11-MUA layer since PL was used as a bridging molecule for ferredoxin adsorption due to its net positive charge. Ferredoxin/PL/11-MUA structured hetero-layer was constructed due to the adsorption of negatively charged ferredoxin on positively charged PL/11-MUA hetero-layer. The surface of ferredoxin adsorbed PL/11-MUA layer was observed by atomic force microscope (AFM). The hetero-film formation was verified by surface plasmon resonance (SPR) measurement. The current flow and rectifying property based on the scanning tunneling spectroscopy (STS) I–V characteristics was achieved in the proposed hetero-layer. Thus, the hetero-layer structure of ferredoxin was functioned as the biomolecular diode with rectifying property. The proposed biomolecular diode can be usefully applied for the development of molecular-scale bioelectronic devices.

Molecular logic gate device with “OR” logic function was developed. The “OR” function logic gate was fabricated by the double line structured bio-photodiode, depicted as A and B line, consisted of Green fluorescent protein/viologen/cytochrome c hetero-LB film. When a light was irradiated to a single (A or B) or double (A and B) line bio-photodiode as an input, the steady state photocurrent was generated in part of (A+B) as an output. The photocurrent intensity generated in one line input was lower than that of twin line input. The high photocurrent intensity indicates “1,1” in truth tables and low photocurrent indicates “0,1” or “1,0”. Finally, “0,0” input corresponds to a dark state without light generation. The “OR” logic gate function was successfully achieved based on high- and low-photocurrent by threshold.

Photoinduced electron transport processes in hetero-Langmuir–Blodgett (LB) films composed of electron sensitizer (S), relay (R) and acceptor (A) molecules were investigated by femtosecond transient absorption technique. 7,8-Dimethyl-10-dodecyl isoalloxazine (flavin), N -allyl- N ′-[3-propylamido- N ″, N ″-di( n -octadecyl)]-4,4′-bipyridium dibromide (viologen) and N -docosilquinolinium tetracyanoquinodimethane (TCNQ) were employed as S, R and A units, respectively. Based on the time-resolved transient absorption spectra of S/R/A series hetero-LB films with different numbers of R layers, the optimum number of R layers for efficient photoinduced charge transport from S to A layers via R was determined to be two. Over two layers of R molecules in the S/R/A series LB films, the charge transport rate became slower due to an increase in the back electron transport from R to A layers. S(30 layers)/A(31 layers) (S(30)/A(31)) hetero-LB film exhibits nearly the same charge transport rate as S(30)/R(2)/A(31) hetero-LB film. But the charge recombination from A to S occurred in S(30)/A(31) hetero-LB film. In the S(30)/A(31) hetero-LB film, charge separated species were directly monitored in the transient absorption spectra. At 660 nm, a long decay component become manifest due to the contribution of bulk (TCNQ) 2 − species. At 740 and 840 nm, on the other hand, a slow rise and long-time decay components were observed due to the contribution of TCNQ − monomer existing at the interface between S and A layers.

A bioelectronic device consisting of protein-adsorbed hetero-Langmuir–Blodgett (LB) films was investigated. Four kinds of functional molecules, cytochrome c , viologen, flavin, and ferrocene, were used as a secondary electron acceptor (A 2 ), a first electron acceptor (A 1 ), a sensitizer (S), and an electron donor (D), respectively. To fabricate the cytochrome c adsorbed hetero-LB film, poly- l -aspartic acid was used as the bridging molecule. The hetero-LB film was fabricated by subsequently depositing ferrocene, flavin, and viologen onto the pretreated ITO glass. Cytochrome c -adsorbed hetero-LB films were prepared by the adsorption of cytochrome c onto the poly- l -aspartic acid treated-LB films by intermolecular electrostatic attraction. Finally, the MIM (metal/insulator/metal) structured molecular device was constructed by depositing aluminum onto the surface of the cytochrome c -adsorbed hetero-LB films. Hetero-LB films were analyzed by Atomic Force Microscopy (AFM), and cytochrome c adsorption onto the films confirmed. The photoswitching function was achieved and the photoinduced unidirectional flow was in accordance with the rectifying characteristics of the molecular device. The direction of energy flow was in accordance with the energy level profile across molecular films. Based on the measurement of the transient photocurrent of the molecular device efficient directional flow of photocurrent through the redox potential difference was observed. The photodiode characteristics of the proposed bio-electronic device were verified and the proposed molecular array mimicking the photosynthetic reaction center could be usefully applied as a model system for the development of the bio-molecular photodiode.

A molecular photodiode with the hetero-Langmuir–Blodgett (LB) film consisting of an electron donor (D), sensitizer (S), relay (R), and acceptor (A) was fabricated. Ferrocene octadecyl amine (Ferrocene), 7,8-dimethyl-10-dodecyl isoalloxazine (flavin), N-Allyl-N′-[3-propylamido-N″,N″-di(n-octadecyl)]-4,4′-bipyridium dibromide (viologen) and N-docosilquinolinium tetracyanodimethan (TCNQ) were used as the D, S, R, and A units, respectively. By aligning the hetero-LB film of the D/S/R/A units on indium tin oxide (ITO) coated glass with an aluminum thin film, a molecular photodiode with a Metal/Insulator/Metal (MIM) structure was constructed. The decay of the transient photocurrent of MIM device was measured using a 355 nm Nd:YAG pulse laser as the light source and the charge transfer rate was obtained. The charge transfer rate was faster in the D/S/R/A heterojunction than in S/R and S/R/A heterojunction devices due to less recombination from the A to S and less back electron transport due to the existence of D molecules. Various effects such as the LB film thickness, interface structure, and Schottky barrier on the charge transfer rate were investigated. The results showed that the charge transport efficiency of the molecular photodiode became higher when the LB film thickness increased and the head/head interfaced structure of the S/R hetero LB films was adopted. Furthermore, improvement of the molecular device efficiency occurred when spacer molecules were adopted between the electrode and the LB film.

Molecular pattern formation using chemically modified cytochrome c and green fluorescent protein (GFP) was presented for the application as a bioelectronic device. A protein conjugate was synthesized by the formation of disulfide bridges. In order to make molecular assembly onto the gold-coated substrate, cytochrome c was cross-linked with N-succinimidyl-3-(2-pyridyldithio)propionate (SPDP). After the modification of cytochrome c, it was spontaneously deposited, so that it could be adsorbed onto the gold-coated substrate by self-assembly (SA) technique. Using the cellulose membrane, cytochrome c molecules were deposited onto the gold-coated substrate with the spatial resolution of ca. 0.2 μm. In order to verify the modified cytochrome c, UV absorption spectrum was measured. GFP was adsorbed onto the cytochrome c monolayer by electrostatic force. Fluorescence emission spectrum was investigated to verify the existence of the GFP molecule onto the cytochrome c monolayer. To verify the adsorption of cytochrome c molecules onto the gold-coated substrate and GFP molecules onto the cytochrome c monolayer, the atomic force microscopy and lateral force microscopy investigations were performed. Molecular pattern formation of cytochrome c and GFP molecules were successfully performed by chemical means and electrostatic force.

Bioelectronic device based on photoinduced electron transfer such as the biomolecular photodiode consisting of protein-adsorbed hetero film was investigated. Three kinds of functional molecules in biomolecular photodiode were used as a sensitizer, a first electron acceptor, and a second electron acceptor. The hetero-film was fabricated subsequently depositing functional molecules onto the pretreated conducting substrate using self-assembly method and Langmuir–Blodgett film method. The metal/insulator/metal structured bioelectronic device was constructed by depositing the metallic electrode onto the surface of the hetero-films. Based on the photoelectric response properties, the rectifying property in the current–voltage characteristic and the photoswitching effect of the proposed bioelectronic device were observed. The charge separation of molecular interface was verified in time-resolved fluorescent measurement by the time-correlated single photon counting method. The charge shift in the device was analyzed by the measurement of transient photocurrent of the device and thus the efficient directional flow of photocurrent through the redox potential difference was observed.

Photoinduced electron transfer in biomolecular photodiode consisting of protein-adsorbed hetero-Langmuir–Blodgett (LB) films was investigated. Four kinds of functional molecules, cytochrome c, viologen, flavin, and ferrocene, were used as a second electron acceptor, a first electron acceptor, an electron sensitizer, and an electron donor, respectively. The hetero-LB film was fabricated by subsequently depositing ferrocene, flavin, and viologen onto the pretreated ITO glass. Cytochrome c-adsorbed hetero-LB films were prepared by soaking the hetero-LB films into the phosphate buffer solution containing cytochrome c. To verify the optimal adsorption conditions of cytochrome c molecules onto the viologen LB layers, the UV-absorption spectrum and atomic force microscopy observations of LB films were performed. Finally, the metal/insulator/metal structured molecular device was constructed by depositing aluminum onto the surface of the cytochrome c-adsorbed hetero-LB films. For photoelectric response properties, the current–voltage characteristic and photoswitching effect of the proposed molecular photodiode were investigated. To verify the charge shift, transient photocurrent of the molecular photodiode was measured.

The photoinduced electron transfer rate in hetero-Langmuir–Blodgett (LB) films, composed of electron sensitizing protein and electron accepting organics, was investigated. The hetero-LB film was fabricated by sequentially depositing green fluorescence protein (GFP), viologen, and TCNQ, which functioned as an electron sensitizer, a relay, and an acceptor, respectively. To verify the hetero-LB film formation, surface morphologies of the GFP film and viologen/TCNQ LB film were observed by atomic force microscopy (AFM). The fast charge separation of the molecular interface was investigated by analyzing the time-resolved fluorescence decays of GFP homo-, GFP/viologen hetero- and GFP/viologen/TCNQ hetero-LB film using a time-correlated single photon counting (TCSPC) method. In GFP/viologen hetero-films, the fluorescence decay of excited GFP was faster than that in the GFP homo-film. Based on the decay of fluorescence the charge separation rates of excited GFP were calculated. The fluorescence lifetime and charge separation rate of the GFP/viologen/TCNQ hetero-LB film increased slightly compared to that of the GFP/viologen hetero-LB film as a result of the addition of the TCNQ layer, electron acceptor. On the basis of its molecular interface charge separation behavior, the proposed molecular array can be used as a component of the molecular photodiode.

Photoinduced electron transfer in the molecular electronic device consisting of protein-adsorbed hetero Langmuir-Blodgett (LB) film was investigated. Three kinds of functional molecules, cytochrome c, viologen, and green fluorescent protein (GFP) were used as an electron acceptor, a mediator, and a sensitizer, respectively. The hetero-LB film was fabricated by subsequently depositing cytochrome c and viologen onto the pretreated ITO or quartz glass. GFP adsorbed hetero-LB films were prepared by soaking the hetero-LB films into the buffer solution containing GFP. The MIM (metal/insulator/metal) structured molecular device was constructed by depositing aluminum onto the surface of the GFP-adsorbed hetero LB films. Due to the excitation by irradiation with a 460 nm monochromic light source, the photoinduced unidirectional flow of electrons in the MIM device could be achieved and was detected as photocurrents. The photoswitching function was achieved and the rectifying characteristic was observed in the molecular device. Based on the measurement of transient photocurrent of molecular device, the unidirectional flow of electrons was verified.

The optimal fabrication condition of cytochrome c Langmuir-Blodgett (LB) film was investigated. To verify the pH dependence of cytochrome c film formation, the various π-A isotherms were obtained at pH 6.0, 7.0, 8.0, 9.0, and 10.0, respectively. The cytochrome c LB films were then fabricated onto the quartz substrate, and the deposition of cytochrome c LB films was investigated by UV-visible spectroscopy.

Photoinduced electron transfer in molecular hetero- Langmuir-Blodgett (LB) films consisting of Green fluorescent protein (GFP)/viologe/TCNQ was investigated. In this work, charge transfer process in the molecular hetero-films has been investigated by femto-second transient absorption spectroscopy. Based on the transient absorption in the GFP/viologen/TCNQ series hetero-films, charge transfer from excited GFP to viologen (TCNQ) was observed with subpicosecond time resolution.

A shift register memory of molecular photodiode, consisting of flavin/viologen/TCNQ molecular hetcro-LB film, at the molecular level is described. In the shift register memory device, the free electrons of sensitizer molecules have an excited or ground (“1” or “0”) state and the electrons are shifted between the functional molecules with photoinduced electron transfer reactions. Based on the transient photocurrent measurement, the shift register memory functions of molecular photodiode were observed with nanosecond time resolution.

The charge transfer characteristics of molecular homo-films composed of green fluorescence protein (GFP) were investigated by time-resolved fluorescence measurement. In this work, time-resolved fluorescence decay of GFP homo film was measured to investigate the solid-state fluorescence lifetime and to observe the charge transfer by using time-correlated single photon counting method (TCSPC).

The charge transfer characteristics of molecular hetero-LB films composed of green fluorescence protein (GFP), viologen, and cytochrome-c were investigated by transient fluorescence measurement. In this work, transient fluorescence decay of GFP homo film and GFP/viologen/cytochrome-c hetero films were measured to investigate the charge separation rate and transport mechanism by using time-correlated single photon counting method (TCSPC).

Direct beam patterning on metal/protein/organic material coated ITO substrates is investigated using laser light for submicron scale lithography. A laser writing lithography method is developed using the 400nm Ti:Sapphire laser. Using a microscope objective lens a laser beam is focused onto a glass slide coated with metal/protein/organic material film. Localized laser absorption results in partial melting and ablation of film. Spatially moving the laser spot, a stable etched pattern is obtained at submicron resolution. This result opens many possibilities for microfabrication of bioelectronic devices.

The formation of molecular hetero-film consisting of green fluorescence protein (GFP) and viologen LB film using the electrophoretic sedimentation technique (EPS) is investigated. The fabrication condition by EPS such as the exposure voltage affects the topology and photoresponse of GFP films. Based on the surface topology measured by atomic force microscopy (AFM), the optimal electric field for the fabrication of GFP film was found as 4.5V.

Photoelectrical properties of biomolecular heterostructures are investigated. Ferredoxin and chlorophyll a were used as an electron acceptor and a sensitizer in the heterostructure by mimicking the photosynthesis. Self-assembly layer of ferredoxin was formed on Au-coated glass, and then chlorophyll a was deposited onto the ferredoxin layer by Langmuir–Blodgett method. The photoinduced current flow was observed by repeated step illumination of 488nm light irradiation. The rectifying property by the scanning-tunneling-spectroscopy-based current–voltage characteristic was achieved in the ferredoxin∕chlorophyll a heterostructure. The ferredoxin∕chlorophyll a heterostructure was functioned as the molecular diode and switching device with photocurrent generation and rectifying property. Proposed molecular diode can be usefully applied for the development of molecular-scale bioelectronic devices such as the diode, switch, and solar cell.

A bio-photodiode was fabricated using an array of electronically functional molecular layers, which consisted of a thin film of the green fluorescent protein and organic hetero-Langmuir–Blodgett layers between metal electrodes. With repeated step light illumination, the photocurrent was generated accordingly, which indicates a photoswitching function. Under illumination, the rectified photocurrent of the bio-photodiode was observed from current–voltage measurements. To verify the switching function and charge transfer through the functional molecular layers, transient photocurrents were measured. In transient photocurrent measurements, unidirectional charge flows generated by the redox potential difference through the molecular layers were observed.

By mimicking the biological photosynthesis system, molecular photodiode was developed artificially using molecular array consisting of protein/organic molecular hetero-thin films. Functional organic molecule (viologen) and biomolecules (green fluorescent protein, GFP) were chosen and used as an electron acceptor (A) and the electron sensitizer (S), respectively. Based on the redox potential of each molecules obtained by cyclic voltammetry measurement, molecular thin films were successfully fabricated by aligning the viologen (A) Langmuir–Blodgett film (LB) onto ITO glass and subsequently adsorbing GFP (S) molecules onto the viologen LB film surface. By depositing aluminum (Al) onto GFP/viologen hetero-thin films, a metal/insulator/metal (MIM) structured device was constructed. When the forward bias was applied to the fabricated device in accordance with the energy profile of the prepared thin films, photoswitching function could be obtained.

This paper introduces approaches that combine micro/nanomolding, or nanoimprinting, techniques with proximity optical phase mask lithographic methods to form three dimensional (3D) nanostructures in thick, transparent layers of photopolymers. The results demonstrate three strategies of this type, where molded relief structures in these photopolymers represent (i) fine (1 microm) features that serve as the phase masks for their own exposure, (ii) coarse features (1 microm) that are used with phase masks to provide access to large structure dimensions, and (iii) fine structures that are used together phase masks to achieve large, multilevel phase modulations. Several examples are provided, together with optical modeling of the fabrication process and the transmission properties of certain of the fabricated structures. These approaches provide capabilities in 3D fabrication that complement those of other techniques, with potential applications in photonics, microfluidics, drug delivery and other areas.

The oxidation-reduction control to store charges in self-assembled ferredoxin layer was investigated by scanning electrochemical method. Micro sized spot arrays consisting of ferredoxin proteins which used as the storage element were formed on chemically modified gold coated glass by micro contanct printing method. The formation of ferredoxin array was confirmed by the atomic force microscopy. The charge store was investigated by external applied reduction potential to ferredoxin as a write function, and the stored reducing charge was measured as a read function of storage applications. In the reduction state, the stored charge was maintained for around 90 sec. This ferredoxin layer can be used as the molecular size information storage by applying the reducing potential and measuring the current flow when achieving the current of individual ferredoxin molecule.

Three-dimensional (3D) intensity distributions generated by light passing through conformal phase masks can be modulated by the absorption property of photosensitive materials. The intensity distributions have extremely long depth of focus, which is proportional to the size of the phase masks, and this enables one to pattern thick (approximately 100 microm), nanoporous structures with precise control of grade density. Various density-graded 3D structures that result from computational modeling are demonstrated. Results of x-ray radiograph and the controlled absorption coefficient prove the dominant mechanism of the generated graded density is absorption of the photosensitive materials. The graded-density structures can be applied to a chemical reservoir for controlled release of chemicals and laser target reservoirs useful to shape shockless wave compression.

In living organisms the photosynthesis involves the absorption of light by the light-harvesting (LH) antenna complexes. By mimicking the photosynthesis process the artificial photonic device composed of bio-molecular hetero structure is developed. The proposed photonic device is composed of Chl a, Chl b, phycoerythrin and phycocyanin. To fabricate the highly ordered structure of biomolecules, the deposition of ordered Chl a/Chl b molecules onto solid substrates was done by the Langmuir-Blodgett (LB) technique, and the self-assembly technique was used for the deposition of phycocyanin molecule. To optimize the photocurrent generation, the photoelectric response characteristics of Chl a and Chl b LB films were measured according to the number of deposition layers, and effects of phycocyanin layer and various phycoerythrin concentrations on the photocurrent generation were analyzed. The biophotonic device was fabricated by the combination of the hetero biofilms and the photocurrent generation of the proposed device was observed. It was observed that the photocurrent generation of the proposed biodevice was improved by using the appropriate biopigments to be selected. The proposed artificial biophotonic device consisting of biopigments can be used to generate photocurrent by mimikng the photosynthesis in living system.

Control of spectral bandwidth, illumination angle, and degree of collimation of light passing through a conformable phase mask provides an experimentally simple route to nanostructured materials with well defined depth gradients in density (i.e., porosity). In this approach, the illumination conditions define spatial variations in visibility of the distributions of intensity. Exposure of photopolymers to these intensity distributions generates, after developing, solid structures with geometries that compare well with expectation based on modeling of the optics. A range of structures is demonstrated, some of which have potential applications ranging from targets for laser fusion to vehicles for controlled release of chemicals.