Remote wound monitoring of chronic ulcers.

Chronic wounds or ulcers are wounds that do not heal in the usual manner. This type of wound is most common in the elderly and in paraplegic patients with an estimated 1% of the population suffering from leg ulcers and the costs adding up to 4% of the annual National Health Service budget in the U.K. There is an identified need to develop a device capable of remote wound monitoring that enables patients to take charge of their wound management under clinical guidance. A new ¿wound mapping¿ device has been developed, which is based on electrical impedance spectroscopy and involves the multifrequency characterization of the electrical properties of wound tissue under an electrode array. A key feature of the prototype device is the anticipated incorporation of the measuring array into standard commercial occlusive dressings, thereby protecting the wound from interference and contamination, and thus, promoting wound healing, while monitoring the protected wound. Further development is planned including wireless transmission, thus enabling telewound monitoring as described earlier.

Development of a multi--electrode electrical stimulation device to improve chronic wound healing.

A new device has been developed for the application of Electrical Stimulation to improve healing of chronic wounds. The device enables the creation of a composite electrode hence matching the electrode(s) to the size and shape of the wound. Up to 49 electrodes in an array can be combined, delivering High Voltage Pulsed Current (HVPC) in the range 60-120 Hz with a pulse duration range from 90-110 mus and the possibility of treating the patient with direct current instead of HVPC. In addition, the software can import the measurements from the ImpediMap device, analysing the electrical impedance of the tissues involved. A test on healthy volunteers did not prove a statistically significant rise in skin temperature, TcPO2 or impedance due to the stimulation, even though a slight reddening of the stimulated site was observed.

Characterisation of a multi-frequency wound impedance mapping instrument.

A new instrument has been developed enabling clinicians to map and study the healing process of a wound. Early assessment of the instrument demonstrated promising results both during bench testing as well as during initial in vivo measurements on a skin abrasion. Clear differences between healthy and wounded tissue were demonstrated and a pattern was observed, potentially indicative of the healing process for this particular wound.

Nickel hexacyanoferrate modified screen-printed carbon electrode for sensitive detection of ascorbic acid and hydrogen peroxide.

Electrochemically modified screen-printed carbon electrode (SPCE) has been prepared by electrodepositing nickel hexacyanoferrate(III) (NiHCF) onto the electrode surface using cyclic voltammetry (CV). The performance of NiHCF-SPCE sensor was characterized and optimized by controlling several operational parameters. The NiHCF film has been proven to remain stable after CV scanning from 0 to +1.0 V vs. Ag/AgCl in the pH range of 3 to 10 and is re-useable. The most favourable supporting electrolyte solution exhibiting the optimum electroanalytical performance of the NiHCF-SPCE sensor was found to be 0.2 mol/L sodium nitrate. The electrochemical response toward ascorbic acid (AA) and H2O2 in 0.2 mol/L sodium nitrate solution was studied by using CV and the results showed that both analytes were electrocatalytically oxidized at approximately +0.4 V, while H2O2 also revealed a reduction signal at -0.8 V vs. Ag/AgCl. The NiHCF-SPCE sensor exhibited highly linear response for AA and H2O2 in the examined concentration range from 5.0x10-5 to 1.5x10-3 mol/L and from 2.0x10-5 to 1.0x10-3 mol/L (at +0.4 V), with the correlation coefficients of 0.999 and 0.998, respectively. The reproducibility of the NiHCF-SPCE sensor was followed for the determination of AA by using four individual electrodes, and the relative standard deviation of CV peak currents varied between 0.9 % and 2.2 %. The proposed NiHCF-SPCE has been shown to be a very attractive electrochemical sensor for AA and H2O2, also in a view of inexpensive mass production of disposable single-use sensors. The NiHCF-SPCE sensor was tested by measuring AA in multivitamin tablets, with recoveries obtained between 94.4 % and 108.2 % (n=5).

Thin film platinum cuff electrodes for neurostimulation: in vitro approach of safe neurostimulation parameters.

Thin film technology takes more and more importance in the development of biomedical devices dedicated to functional neurostimulation. Our research about the design of implant neurostimulating electrode is oriented toward thin film cuff electrodes based on a polyimide substrate covered by a chromium/gold/Pt film. The chromium/gold sputtered film serves as adhesion layer and current collector whereas platinum acts as an electrochemical actuator. The electrode surface has been designed to obey safe stimulation criteria (i.e. chemically inert noble metal, low electrode-electrolyte impedance, high electrochemical reversibility, high corrosion stability). The electrochemical behaviour of such platinum electrodes has been assessed and compared to a foil of platinum. Extensive in vitro characterisations of the both electrode types were carried out using AFM, SEM and electrochemical techniques. The role of enhanced surface roughness enabling high double layer capacitances to be achieved was clearly highlighted. The obtained results are discussed, with particular reference to thin film electrodes stability under in vitro electrical stimulation in NaCl 0.9% (physiological serum). Therefore, these thin film devices showed reversible PtOH formation and decomposition making them potentially attractive for the fabrication of implant stimulation cuff electrodes.