Quick & accurate characterisation for a wide range of materials.
Experience effortless sheet resistance measurements with the system's easy-to-use PC software.
Part of the Institute of Physics award-winning Ossila Solar Cell Prototyping Platform, Ossila's Four-Point Probe System is an easy-to-use tool for the rapid measurement of sheet resistance, resistivity, and conductivity of materials.
Using our own source measure unit, we have been able to create a low-cost system that allows a wide measurement range. The probe head uses spring-loaded contacts instead of sharp needles, preventing damage to delicate samples, such as polymer films with thicknesses on the order of nanometres.
The system includes a four-point probe, source measure unit, and easy-to-use PC software - enabling more laboratories to measure sheet resistance for the affordable price of £1800.00. It is also covered by ourFREE 2-year warranty .
Features
Wide Current Range - The four-point probe is capable of delivering currents between 10 nA and 150 mA, and can measure voltages from as low as 100 μV up to 10 V. This results in a sheet resistance measurement range of 3 mΩ/□ to 10 MΩ/□, enabling the characterisation of a wide range of materials.
Easy-to-Use - Just plug in the system, install the software, and you're ready to go! The intuitive interface and clean design makes the four-point probe easy-to-use, simplifying the measurement of sheet resistance. Substrates of various shapes and sizes can be used.
High Accuracy - Positive and negative polarity measurements can be performed using the PC software. This enables you to calculate the average sheet resistance between positive and negative currents - eliminating any voltage offsets that may have occurred, hence increasing the accuracy of your measurements.
Non-Destructive Testing - Designed with the measurement of delicate samples in mind, the four-point probe head utilises gold-plated, gentle spring-loaded contacts with rounded tips. This results in a constant contact force of 60 grams, preventing the probes from piercing fragile thin films, whilst still providing good electrical contact.
Space-Saving Design - Through careful design consideration, we have been able to keep the footprint of the four-point probe to a minimum (total bench area of 14.5 cm x 24 cm), allowing it to be used even in busy labs where shelf space is lacking.
Rapid Material Characterisation - The PC software (included with the system) performs all the necessary measurements and calculations for sheet resistance, resistivity, and conductivity - making material characterisation effortless. It also automatically performs correction factor calculation.
Easily Repeat Experiments - The settings used for a measurement are saved along with the data, making it easy to look up the details of the experiment. Furthermore, these settings files can be loaded by the same software, speeding up repeat measurements and material characterisation. With less time required for repeat measurements, your research output can be significantly increased.
Measurement Specifications
| Voltage range | ±100 μV to ±10 V |
| Current range | ±1 μA to ±150 mA |
| Sheet resistance range | 3 mΩ/□ to 10 MΩ/□ (ohms per square) |
| Measurement accuracy | < ±4% |
| Measurement precision | ±0.5% |
Physical Specifications
| Probe Spacing | 1.27 mm |
| Rectangular Sample Size Range | Long Edge Minimum: 5 mm Short Edge Maximum: 60 mm |
| Circular Sample Size Range (Diameter) | 5 mm to 76.2 mm |
| Maximum Sample Thickness | 10 mm |
| Overall Dimensions | Width: 145 mm Height: 150 mm Depth: 240 mm |
- Clean and intuitively-designed interface
- Data saved to .csv file
- Calculates resistivity and conductivity for samples with a known thickness
- Automatic correction factor calculation
- Save & load previously-used settings
An intuitive and user-friendly standalone PC program is used to control the four-point probe measurement, enabling rapid characterisation of materials without the need for the user to write any code themselves. This PC software calculates appropriate geometrical correction factors for the given sample geometry, ensuring accurate results. It can also calculate the resistivity and conductivity of the sample, if the thickness is provided, to allow for extensive electrical characterisation of materials.
The software saves data to comma-separated value (.csv) files, facilitating importing the data into your preferred analysis software. The settings are also saved along with the data, so you won't have to worry about losing your lab diary when trying to remember the details of your experiments. Furthermore, these settings files can be loaded by the program, making it much simpler and faster to repeat an experiment or use the same/similar settings again.
Software Requirements
| Operating System | Windows Vista, 7, 8, or 10 (32-bit or 64-bit) |
| CPU | Dual Core 2 GHz |
| RAM | 2 GB |
| Available Hard Drive Space | 178 MB |
| Monitor Resolution | 1440 x 900 |
| Connectivity | USB 2.0, or Ethernet (requires DHCP) |
Material Characterisation - Resistivity is an inherent characteristic of a material, and an important electrical property. It can be determined by measuring the sheet resistance of a thin film with a known thickness, making the four-point probe measurement a key technique for the electrical characterisation of materials.
Thin-Film Solar Cells and LEDs - Thin-film devices (such as perovskite solar cells or organic LEDs) require thin conducting electrodes that transport electrical charge laterally to be extracted. Therefore, materials with low sheet resistances are required to reduce potential losses at this stage. This becomes even more important when attempting to scale up these devices, as the electrical charges will have to travel further along the electrodes before they can be extracted.
Please note, this system may not be suitable for silicon or other materials which naturally form insulating oxide layers. To measure such materials, the oxide layer needs to be penetrated by the probes, which may not be possible with the spring-loaded, round tipped probes utilised by this system.
The four-point probe is the most commonly-used piece of equipment for measuring the sheet resistance of a material. Sheet resistance is the resistivity of a material divided by its thickness, and represents the lateral resistance through a thin square of conducting/semiconducting material. This measurement uses four probes arrayed in a line, with equal spacing between each probe. A current is passed between the outer two probes, causing a reduction in voltage between the inner two probes. By measuring this change in voltage, the sheet resistance can then be calculated using the following equation:
Here, I is the applied current and ΔV is the decrease in voltage between the inner probes. The result of this equation must further be multiplied by a geometric correction factor based upon the shape, size, and thickness of the sample. This accounts for limitations to the possible current pathways through the sample, which affects the values that are measured.
A more in-depth explanation of the theory behind sheet resistance, geometric correction factors, and the four-point probe technique can be found in our Guide to Sheet Resistance Theory.
Frequently Asked Questions
What sample thicknesses are compatible with the system?
The Four-Point Probe System is specifically designed to enable the measurement of thin films in the nanometre range. For example, we have successfully measured 30 – 40 nm films of PH 1000 PEDOT:PSS and < 100 nm silver nanowire films on PET, without creating holes in the thin films. For a more in-depth explanation, please see our application note: Sheet Resistance Measurements of Thin Films.
Do I need my own source measure unit (sourcemeter)?
The system has a built-in Ossila Source Measure Unit (SMU), so you don’t need to already have one. If you wish to use your own SMU, the Probe Station includes a four-point probe head without a SMU. However, the Ossila Sheet Resistance software is only compatible with Ossila’s SMU, and cannot be used with others.
What resistivity/conductivity range can the system measure?
As the system measures the sheet resistance of a sample, a general range of measurable resistivities or conductivities cannot be given. This is because the measurable resistivity range depends on the thickness of the sample being tested. The resistivity of a sample can be calculated from its sheet resistance and thickness using the following equation:
The system is capable of measuring between 3 mΩ/□ and 10 MΩ/□, so if we use these values in the formula above with a sample 50 nm thick, then the resistivity (conductivity) range that can be measured by the system will be 0.5 nΩ.m to 500 mΩ.m (2 S/m to 2 GS/m). If the sample is 400 µm thick, then the resistivity (conductivity) range of the system is 4 µΩ.m to 4 kΩ.m (250 µS/m to 250 kS/m). Below is a table of the resistivity and conductivity ranges of the system for samples with thicknesses of different orders of magnitude:
| Sample Thickness | Resistivity Range | Conductivity Range |
| 10 nm | 30 pΩ.m - 100 mΩ.m | 10 S/m - 30 GS/m |
| 100 nm | 300 pΩ.m - 1 Ω.m | 1 S/m - 3 GS/m |
| 1 µm | 3 nΩ.m - 10 Ω.m | 100 mS/m - 300 MS/m |
| 10 µm | 30 nΩ.m - 100 Ω.m | 10 mS/m - 30 MS/m |
| 100 µm | 300 nΩ.m - 1 kΩ.m | 1 mS/m - 3 MS/m |
| 1 mm | 3 µΩ.m - 10 kΩ.m | 100 µS/m - 300 kS/m |
Do you offer other probe designs?
Currently we offer a single probe layout, i.e. linear with 1.27 mm spacing between the probes, 0.48 mm probe diameter, and 60 g spring pressure. This allows us to maintain the affordable price of the Four-Point Probe System, whilst still providing reliable and accurate measurements of sheet resistance.
Does the price include everything?
Yes, everything shown on the product page is included! The source-measure unit, four-point probe head, linear translation stage, software, even an ITO-coated glass substrate!
To the best of our knowledge the technical information provided here is accurate. However, Ossila assume no liability for the accuracy of this information. The values provided here are typical at the time of manufacture and may vary over time and from batch to batch.
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然后往容器中滴液体直至读数为0.70时就可以了
我们每天长时间都在实验室里和移液器（俗称“枪”）打交道，枪已经成为实验室标配，因为它是很多实验过程和分析的基础。但正因为如此，我们都认为它很简单，就像走路和呼吸一样自然，不需要你花任何心思，它就可以做你想做的事情。但事实真的是这样吗？
事实上，枪虽小但往往关系到实验结果的准确性，有小伙伴经常抱怨枪老出问题：
1.用了一段时间就不准漏液了？
2.液体容易倒吸？
3.移液排不干净？……
到底是哪里出问题了呢，你有没有碰到这样的迷之困惑？
当当当，福利到，来自梅特勒-托利多瑞宁移液技术专家自告奋勇来解答大伙儿的困惑，有任何关于移液器使用的问题欢迎来和我们探讨共同进步哟~
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我们会每天抽时间统一回复大家的问题，专家答疑截止12月31日哦！
塑料类工具灭菌有什么需要注意的吗？谢谢！
2、吸液：用右手的拇指和中指捏住移液管的上端，将管的下口插入欲吸取的溶液中，插入
不要太浅或太深，一般为10～20mm处，太浅会产生吸空，把溶液吸到洗耳球内弄脏溶液，
太深又会在管外沾附溶液过多。左手拿洗耳球，接在管的上口把溶液慢慢吸入，先吸入该管 容量的1/3
左右，用右手的食指按住管口，取出，横持，并转动管子使溶液接触到刻度以上 部位，以置换内壁的水分，然后将溶液从管的下口放出并弃去，如此用反复洗3
次后，即可 吸取溶液至刻度以上，立即用右手的食指按住管口。 3、调节液面：将移液管向上提升离开液面，管的末端仍靠在盛溶液器皿的内壁上，管身保
持直立，略为放松食指（有时可微微转动吸管）使管内溶液慢慢从下口流出，直至溶液的弯
月面底部与标线相切为止，立即用食指压紧管口。将尖端的液滴靠壁去掉，移出移液管，插 入承接溶液的器皿中。
4、放出溶液：承接溶液的器皿如是锥形瓶，应使锥形瓶倾斜30°，移液管直立，管下端紧
靠锥形瓶内壁，稍松开食指，让溶液沿瓶壁慢慢流下，流完后管尖端接触瓶内壁约15 秒后，
再将移液管移去，残留在管末端的少量溶液，不可用外力强使其流出，因较准时已考虑了末 端保留的溶液的体积。
大家做溶出曲线稀释溶液时有某有再用移液枪？移液枪量取1ml的体积准确不？
